Saturday, December 22, 2007
HIV infections
HIV infections
Health worker examining a child
The human immunodeficiency virus (HIV) is a retrovirus that infects cells of the human immune system, destroying or impairing their function. In the early stages of infection, the person has no symptoms. However, as the infection progresses, the immune system becomes weaker, and the person becomes more susceptible to so-called opportunistic infections.
The most advanced stage of HIV infection is acquired immunodeficiency syndrome (AIDS). It can take 10-15 years for an HIV-infected person to develop AIDS; antiretroviral drugs can slow down the process even further.
HIV is transmitted through unprotected sexual intercourse (anal or vaginal), transfusion of contaminated blood, sharing of contaminated needles, and between a mother and her infant during pregnancy, childbirth and breastfeeding.
Health worker examining a child
The human immunodeficiency virus (HIV) is a retrovirus that infects cells of the human immune system, destroying or impairing their function. In the early stages of infection, the person has no symptoms. However, as the infection progresses, the immune system becomes weaker, and the person becomes more susceptible to so-called opportunistic infections.
The most advanced stage of HIV infection is acquired immunodeficiency syndrome (AIDS). It can take 10-15 years for an HIV-infected person to develop AIDS; antiretroviral drugs can slow down the process even further.
HIV is transmitted through unprotected sexual intercourse (anal or vaginal), transfusion of contaminated blood, sharing of contaminated needles, and between a mother and her infant during pregnancy, childbirth and breastfeeding.
About WHO who fights against health in the world
About WHO
"Our greatest concern must always rest with disadvantaged and vulnerable groups. These groups are often hidden, live in remote rural areas or shantytowns and have little political voice."
Dr Margaret Chan
WHO Director-General
WHO is the directing and coordinating authority for health within the United Nations system. It is responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.
In the 21st century, health is a shared responsibility, involving equitable access to essential care and collective defence against transnational threats.
"Our greatest concern must always rest with disadvantaged and vulnerable groups. These groups are often hidden, live in remote rural areas or shantytowns and have little political voice."
Dr Margaret Chan
WHO Director-General
WHO is the directing and coordinating authority for health within the United Nations system. It is responsible for providing leadership on global health matters, shaping the health research agenda, setting norms and standards, articulating evidence-based policy options, providing technical support to countries and monitoring and assessing health trends.
In the 21st century, health is a shared responsibility, involving equitable access to essential care and collective defence against transnational threats.
Thursday, December 20, 2007
Tuesday, December 18, 2007
AIDS Research Alliance Community Advisory Board (CAB)
AIDS Research Alliance Community Advisory Board (CAB)
CAB application form
FAQ
AIDS Research Alliance (ARA) exists to develop a cure for HIV/AIDS, medical modalities to prevent new infections, and better treatments for those living with HIV.
Does this sound of interest to you?
ARA is recruiting individuals who are affected or infected, medical providers, social service providers, and other concerned members of the community to join the ARA Community Advisory Board (CAB). The ARA CAB is a forum in which various stakeholders in the fight against the HIV/AIDS pandemic come together to help shape how ARA, a community–based research non-profit organization, approaches this challenge.
Since 1989, ARA has been at the forefront of the fight against HIV/AIDS by participating in HIV treatment research that has led to the development of 11 drugs currently used in combination therapy and HAART. ARA has also conducted trials with the aim of advancing therapeutic options for the treatment of HAART-associated conditions including neuropathy, lipodystrophy, and associated metabolic disorders. We are also currently involved in preventative and therapeutic vaccine trials. And there are a number more exciting potential strategies coming down the pipeline.
Another part of ARA’s strategy against HIV/AIDS is its growing community education and outreach component. Outreach activities and educational programming targeting the general public, the at-risk population, those infected and living with the virus, as well as prospective study volunteers are being upgraded and refined as well with the goal of increasing clinical trial participation among communities of color and women. ARA is developing new approaches to best deliver information about HIV/AIDS-related research and how to get involved. Delivering a clear and effective message is key.
The ARA CAB is essential in ensuring that ARA achieves its goals in a way that is relevant to the community we serve. Not only does ARA need the assistance of the CAB to make certain that our messages are on target, relevant, and heard, but ARA will also provide:
* Up-to-date information to CAB members on HIV/AIDS research activities to raise awareness and understanding of key achievements and challenges that lie in this arena;
* Access to trainings to speak on behalf of ARA in educational settings;
* Impact recruitment strategies for potentially life-saving treatments; and
* Networking opportunities among other individuals fighting in their own ways against the HIV/AIDS epidemic.
CAB application form
FAQ
AIDS Research Alliance (ARA) exists to develop a cure for HIV/AIDS, medical modalities to prevent new infections, and better treatments for those living with HIV.
Does this sound of interest to you?
ARA is recruiting individuals who are affected or infected, medical providers, social service providers, and other concerned members of the community to join the ARA Community Advisory Board (CAB). The ARA CAB is a forum in which various stakeholders in the fight against the HIV/AIDS pandemic come together to help shape how ARA, a community–based research non-profit organization, approaches this challenge.
Since 1989, ARA has been at the forefront of the fight against HIV/AIDS by participating in HIV treatment research that has led to the development of 11 drugs currently used in combination therapy and HAART. ARA has also conducted trials with the aim of advancing therapeutic options for the treatment of HAART-associated conditions including neuropathy, lipodystrophy, and associated metabolic disorders. We are also currently involved in preventative and therapeutic vaccine trials. And there are a number more exciting potential strategies coming down the pipeline.
Another part of ARA’s strategy against HIV/AIDS is its growing community education and outreach component. Outreach activities and educational programming targeting the general public, the at-risk population, those infected and living with the virus, as well as prospective study volunteers are being upgraded and refined as well with the goal of increasing clinical trial participation among communities of color and women. ARA is developing new approaches to best deliver information about HIV/AIDS-related research and how to get involved. Delivering a clear and effective message is key.
The ARA CAB is essential in ensuring that ARA achieves its goals in a way that is relevant to the community we serve. Not only does ARA need the assistance of the CAB to make certain that our messages are on target, relevant, and heard, but ARA will also provide:
* Up-to-date information to CAB members on HIV/AIDS research activities to raise awareness and understanding of key achievements and challenges that lie in this arena;
* Access to trainings to speak on behalf of ARA in educational settings;
* Impact recruitment strategies for potentially life-saving treatments; and
* Networking opportunities among other individuals fighting in their own ways against the HIV/AIDS epidemic.
Research Projects on HIV AIDS
Research Projects
Prostratin FAQ
Prostratin: A new therapeutic agent targeting viral reservoirs
Microbicides: An essential new HIV prevention strategy
Prostratin: A new therapeutic agent targeting viral reservoirs
The positive impact of current anti-HIV treatments in decreasing the rate of AIDS progression and death among people living with HIV is undeniable. However, several studies show that even in patients with undetectable plasma viremia (<50 copies/ml), virus rebounds after the interruption of Highly Active Antiretroviral Therapy (HAART) due to the presence of pockets – or reservoirs – of latently infected cells. It is now clear that HAART alone cannot cure HIV. And since the long-term use of HAART is associated with metabolic disorders and toxicities, the identification of new anti-HIV agents with novel mechanisms of action is an important therapeutic goal.
Prostratin was initially isolated as the active constituent of extracts of the tropical plant, homalanthus nutans, used in traditional Samoan herbal medicine for the treatment of “yellow fever” (i.e., hepatitis). The potent antiviral activity of prostratin, combined with its ability to activate HIV expression from latently infected cells, indicates that prostratin may be an important candidate for further development in new anti-HIV therapeutic protocols.
In May of 2001, AIDS Research Alliance was granted an exclusive license by the National Institutes of Health (NIH) to develop prostratin as an anti-HIV drug targeting viral reservoirs. In conjunction with this license, ARA announced in November 2001 a landmark agreement to benefit the people of Samoa, whose indigenous healers have used prostratin medically for generations.
AIDS Research Alliance was then awarded an NIH grant under the NIH-Development of AIDS Related Therapeutics Program (NIH-DART) to perform pre-clinical studies for prostratin. AIDS Research Alliance also established collaborations with multiple laboratories to examine in more detail the latent virus-activating property of prostratin. Results from these experiments have been encouraging. In July 2005, AIDS Research Alliance signed an agreement with a major contract research organization to conduct the remaining pharmacokinetic and toxicology studies of prostratin. The results of these experiments are pending.
* Prostratin Review
* Prostratin Update - 2006
* Prostratin FAQ
* Korin et al., J. Virology, 76 (16), 8118-23, 2002
* Witvrouw et al., Antiviral Chemistry & Chemotherapy, 14:321-328, 2003
* Brooks et al., Immunity, 19 (3), 413-23, 2003
* Biancotto et al, J Virology, 78:10507-15, 2004
* Rullas et al., J Antiviral Chemistry & Chemotherapy 9:545-54, 2004
* (PKC) in response to prostratin or PMA. A paper was published in the journal Antiviral Chemistry & Chemotherapy (Hezareh et al., Antiviral Chemistry & Chemotherapy, 15:207-22., 2004).
Microbicides: An essential HIV prevention strategy
There is an urgent need for more methods to prevent HIV infection, especially those that put women in control. Microbicides are synthetic or natural substances – manufactured in the form of a gel, cream, suppository or film – that can neutralize or kill a microbe. Unlike condoms, an HIV microbicide could be used without the cooperation or knowledge of one’s sexual partner, offering women (and men) who lack the power to avoid sex with partners who may be HIV-infected.
Sexual contact now accounts for 95% of all HIV infections worldwide. In North America the most common sexual practice that leads to HIV infection remains anal sex. Far from being limited to men who have sex with men (MSM), more scientific reports and popular media coverage suggest that it is also a widely practiced sexual behavior in the general heterosexual population, particularly in younger people. It is well established that unprotected anal intercourse (UAI) is a risk for the development of Sexually Transmitted Disease (STD) and HIV infection in men. However, much less is known about the contribution of anal sex, and unprotected intercourse (UI) in particular, to HIV infection in women.
Vaginal microbicide development is already advanced both in the United States and abroad with several Phase III efficacy trials currently underway in Africa. Rectal microbicide development, by comparison, is in its infancy. There are critical basic questions about anal intercourse that need to be answered first. These questions relate to the behavior before, during and after anal sex, and what happens physically to the anal canal and rectum with penetration. Investigators at AIDS Research Alliance, in collaboration with UCLA, are planning studies to address these important questions. The UCLA/ARA study proposes to investigate how anal sex is commonly practiced, what symptoms individuals who have anal sex experience and how they would prefer to apply a potential rectal microbicide.
The study will recruit approximately 900 subjects in Baltimore and Los Angeles with the aim of reaching a wide range of ethnic groups and age ranges of HIV-positive and HIV-negative men and women.
Prostratin FAQ
Prostratin: A new therapeutic agent targeting viral reservoirs
Microbicides: An essential new HIV prevention strategy
Prostratin: A new therapeutic agent targeting viral reservoirs
The positive impact of current anti-HIV treatments in decreasing the rate of AIDS progression and death among people living with HIV is undeniable. However, several studies show that even in patients with undetectable plasma viremia (<50 copies/ml), virus rebounds after the interruption of Highly Active Antiretroviral Therapy (HAART) due to the presence of pockets – or reservoirs – of latently infected cells. It is now clear that HAART alone cannot cure HIV. And since the long-term use of HAART is associated with metabolic disorders and toxicities, the identification of new anti-HIV agents with novel mechanisms of action is an important therapeutic goal.
Prostratin was initially isolated as the active constituent of extracts of the tropical plant, homalanthus nutans, used in traditional Samoan herbal medicine for the treatment of “yellow fever” (i.e., hepatitis). The potent antiviral activity of prostratin, combined with its ability to activate HIV expression from latently infected cells, indicates that prostratin may be an important candidate for further development in new anti-HIV therapeutic protocols.
In May of 2001, AIDS Research Alliance was granted an exclusive license by the National Institutes of Health (NIH) to develop prostratin as an anti-HIV drug targeting viral reservoirs. In conjunction with this license, ARA announced in November 2001 a landmark agreement to benefit the people of Samoa, whose indigenous healers have used prostratin medically for generations.
AIDS Research Alliance was then awarded an NIH grant under the NIH-Development of AIDS Related Therapeutics Program (NIH-DART) to perform pre-clinical studies for prostratin. AIDS Research Alliance also established collaborations with multiple laboratories to examine in more detail the latent virus-activating property of prostratin. Results from these experiments have been encouraging. In July 2005, AIDS Research Alliance signed an agreement with a major contract research organization to conduct the remaining pharmacokinetic and toxicology studies of prostratin. The results of these experiments are pending.
* Prostratin Review
* Prostratin Update - 2006
* Prostratin FAQ
* Korin et al., J. Virology, 76 (16), 8118-23, 2002
* Witvrouw et al., Antiviral Chemistry & Chemotherapy, 14:321-328, 2003
* Brooks et al., Immunity, 19 (3), 413-23, 2003
* Biancotto et al, J Virology, 78:10507-15, 2004
* Rullas et al., J Antiviral Chemistry & Chemotherapy 9:545-54, 2004
* (PKC) in response to prostratin or PMA. A paper was published in the journal Antiviral Chemistry & Chemotherapy (Hezareh et al., Antiviral Chemistry & Chemotherapy, 15:207-22., 2004).
Microbicides: An essential HIV prevention strategy
There is an urgent need for more methods to prevent HIV infection, especially those that put women in control. Microbicides are synthetic or natural substances – manufactured in the form of a gel, cream, suppository or film – that can neutralize or kill a microbe. Unlike condoms, an HIV microbicide could be used without the cooperation or knowledge of one’s sexual partner, offering women (and men) who lack the power to avoid sex with partners who may be HIV-infected.
Sexual contact now accounts for 95% of all HIV infections worldwide. In North America the most common sexual practice that leads to HIV infection remains anal sex. Far from being limited to men who have sex with men (MSM), more scientific reports and popular media coverage suggest that it is also a widely practiced sexual behavior in the general heterosexual population, particularly in younger people. It is well established that unprotected anal intercourse (UAI) is a risk for the development of Sexually Transmitted Disease (STD) and HIV infection in men. However, much less is known about the contribution of anal sex, and unprotected intercourse (UI) in particular, to HIV infection in women.
Vaginal microbicide development is already advanced both in the United States and abroad with several Phase III efficacy trials currently underway in Africa. Rectal microbicide development, by comparison, is in its infancy. There are critical basic questions about anal intercourse that need to be answered first. These questions relate to the behavior before, during and after anal sex, and what happens physically to the anal canal and rectum with penetration. Investigators at AIDS Research Alliance, in collaboration with UCLA, are planning studies to address these important questions. The UCLA/ARA study proposes to investigate how anal sex is commonly practiced, what symptoms individuals who have anal sex experience and how they would prefer to apply a potential rectal microbicide.
The study will recruit approximately 900 subjects in Baltimore and Los Angeles with the aim of reaching a wide range of ethnic groups and age ranges of HIV-positive and HIV-negative men and women.
ntravenous drug use Maternofetal
ntravenous drug use
Sharing unsterilized injection equipment that has been previously used by someone who is infected is an important route of HIV transmission in many countries with a high prevalence of intravenous drug users. In contrast to the accidental needlestick injury (see also Chapter "Post-Exposure Prophylaxis"), the risk of transmission through sharing injection equipment is far higher: the intravenous drug user ensures the proper positioning of the needle by aspiration of blood.
Maternofetal
In the absence of any intervention, an estimated 15-30 % of mothers with HIV infection will transmit the infection during pregnancy and delivery. In approximately 75 % of these cases, HIV is transmitted during late pregnancy or during delivery. About 10 % of vertical HIV infections occur before the third trimester, and 10-15 % are caused by breastfeeding.
In Western countries, perinatal (vertical) HIV infection has become rare since the introduction of antiretroviral transmission prophylaxis and elective cesarean section. For more details, see Chapter "Pregnancy and HIV".
Injection or transfusion of contaminated blood products
In most Western countries, administration or transfusion of HIV-contaminated blood or blood products has become a rare event. With current testing methods (for details see also Chapter "HIV Testing"), the risk of acquiring HIV from a unit of transfused blood is about 1:1,000,000. However, while Western European countries, the United States, Australia, Canada, and Japan have strict and mandatory screening of donated blood for HIV, not all countries do.
Sharing unsterilized injection equipment that has been previously used by someone who is infected is an important route of HIV transmission in many countries with a high prevalence of intravenous drug users. In contrast to the accidental needlestick injury (see also Chapter "Post-Exposure Prophylaxis"), the risk of transmission through sharing injection equipment is far higher: the intravenous drug user ensures the proper positioning of the needle by aspiration of blood.
Maternofetal
In the absence of any intervention, an estimated 15-30 % of mothers with HIV infection will transmit the infection during pregnancy and delivery. In approximately 75 % of these cases, HIV is transmitted during late pregnancy or during delivery. About 10 % of vertical HIV infections occur before the third trimester, and 10-15 % are caused by breastfeeding.
In Western countries, perinatal (vertical) HIV infection has become rare since the introduction of antiretroviral transmission prophylaxis and elective cesarean section. For more details, see Chapter "Pregnancy and HIV".
Injection or transfusion of contaminated blood products
In most Western countries, administration or transfusion of HIV-contaminated blood or blood products has become a rare event. With current testing methods (for details see also Chapter "HIV Testing"), the risk of acquiring HIV from a unit of transfused blood is about 1:1,000,000. However, while Western European countries, the United States, Australia, Canada, and Japan have strict and mandatory screening of donated blood for HIV, not all countries do.
Transmission routes
Transmission routes
There are several ways in which someone can become infected with HIV. These transmission routes are well defined (see also Chapter "Post-Exposure Prophylaxis"). HIV infection can be transmitted through:
* unprotected sexual intercourse with an infected partner;
* injection or transfusion of contaminated blood or blood products (infection through artificial insemination, skin grafts and organ transplants is also possible);
* sharing unsterilized injection equipment that has been previously used by someone who is infected;
* maternofetal transmission (during pregnancy, at birth, and through breastfeeding).
Occupational infections of healthcare or laboratory workers may occur; however, a 1995 study estimated that although 600,000 to 800,000 needlestick injuries occurred among healthcare workers every year in the USA, occupational infection was not frequent. The risk of occupational HIV transmission from contaminated needles to healthcare workers was found to be 0.3 % in case series performed prior to the availability of potent ART.
There are sometimes concerns that there may be alternative routes of HIV transmission. It must be explicitly stated that HIV is NOT transmitted by mosquitoes, flies, fleas, bees, or wasps. HIV is NOT transmitted through casual every day contact. No case of HIV infection has been documented to arise from contact with non-bloody saliva or tears. Since HIV is not transmitted by saliva, it is not possible to contract it through sharing a glass, a fork, a sandwich, or fruit (Friedland 1986, Castro 1988, Friedland 1990). In the opinion of leading experts, exposure of intact skin to HIV-contaminated body fluids (e.g. blood) is not sufficient to transfer the virus.
Sexual intercourse
Unprotected sexual intercourse is the most important transmission route of HIV infection worldwide. Although receptive anal sex is estimated to produce the highest risk of infection, infection after a single insertive contact has also been described. The presence of other sexually transmitted diseases markedly increases the risk of becoming infected with HIV.
The lower the viral load, the less infectious the patient. A prospective study of 415 HIV-discordant couples in Uganda showed that of 90 new infections occurring over a period of up to 30 months, none was from an infected partner with a viral load below 1,500 copies/ml. The risk of infection increased with every log of viral load by a factor of 2.45 (Quinn 2000). It should be noted that the levels of viral load in blood and other body fluids do not always correlate with one another. Thus, individual risk remains difficult to estimate. In addition, HIV-infected patients are not protected from superinfection with new viral strains.
The higher the viral load, the more infectious the patient. This is especially true for patients during acute HIV infection. During acute HIV-1 infection, the virus replicates extensively in the absence of any detectable adaptive immune response, reaching levels of over 100 million copies of HIV-1 RNA/ml (see Chapter "Acute HIV-1 infection").
There are several ways in which someone can become infected with HIV. These transmission routes are well defined (see also Chapter "Post-Exposure Prophylaxis"). HIV infection can be transmitted through:
* unprotected sexual intercourse with an infected partner;
* injection or transfusion of contaminated blood or blood products (infection through artificial insemination, skin grafts and organ transplants is also possible);
* sharing unsterilized injection equipment that has been previously used by someone who is infected;
* maternofetal transmission (during pregnancy, at birth, and through breastfeeding).
Occupational infections of healthcare or laboratory workers may occur; however, a 1995 study estimated that although 600,000 to 800,000 needlestick injuries occurred among healthcare workers every year in the USA, occupational infection was not frequent. The risk of occupational HIV transmission from contaminated needles to healthcare workers was found to be 0.3 % in case series performed prior to the availability of potent ART.
There are sometimes concerns that there may be alternative routes of HIV transmission. It must be explicitly stated that HIV is NOT transmitted by mosquitoes, flies, fleas, bees, or wasps. HIV is NOT transmitted through casual every day contact. No case of HIV infection has been documented to arise from contact with non-bloody saliva or tears. Since HIV is not transmitted by saliva, it is not possible to contract it through sharing a glass, a fork, a sandwich, or fruit (Friedland 1986, Castro 1988, Friedland 1990). In the opinion of leading experts, exposure of intact skin to HIV-contaminated body fluids (e.g. blood) is not sufficient to transfer the virus.
Sexual intercourse
Unprotected sexual intercourse is the most important transmission route of HIV infection worldwide. Although receptive anal sex is estimated to produce the highest risk of infection, infection after a single insertive contact has also been described. The presence of other sexually transmitted diseases markedly increases the risk of becoming infected with HIV.
The lower the viral load, the less infectious the patient. A prospective study of 415 HIV-discordant couples in Uganda showed that of 90 new infections occurring over a period of up to 30 months, none was from an infected partner with a viral load below 1,500 copies/ml. The risk of infection increased with every log of viral load by a factor of 2.45 (Quinn 2000). It should be noted that the levels of viral load in blood and other body fluids do not always correlate with one another. Thus, individual risk remains difficult to estimate. In addition, HIV-infected patients are not protected from superinfection with new viral strains.
The higher the viral load, the more infectious the patient. This is especially true for patients during acute HIV infection. During acute HIV-1 infection, the virus replicates extensively in the absence of any detectable adaptive immune response, reaching levels of over 100 million copies of HIV-1 RNA/ml (see Chapter "Acute HIV-1 infection").
HIV Medicine 2006, Introduction
HIV Medicine 2006, Introduction
Bernd Sebastian Kamps and Christian Hoffmann
The first reports of homosexual patients suffering from previously rare diseases such as pneumocystis pneumonia and Kaposi's sarcoma were published in May 1981 (Centers for Disease Control 1981a, 1981b, 1981c). It soon became clear that the new disease affected other population groups as well, when the first cases were reported in injecting drug users. However, it took almost two years until, in 1983, the human immunodeficiency virus type I (HIV-1) was defined as the primary cause of the acquired immunodeficiency syndrome (Barré-Sinoussi 1983, Broder 1984, Gallo 1984).
Almost 25 years have now elapsed. Twenty-five years, in which HIV infection has changed from a fatal condition to a manageable chronic illness. Twenty-five years, in which the development of antiretroviral therapy (ART) has been one of the dramatic advances in the history of medicine. However, for the vast majority of people living with HIV/AIDS, ART is still light years away - largely inaccessible in resource-poor countries where HIV continues to devastate families, communities and societies, especially the poor and the socially marginalized.
In the following 800 pages, we present a comprehensive overview of the treatment of HIV infection and its complications. As in previous years, all chapters have been thoroughly revised, and most parts of the book were available on the Internet (www.HIVMedicine.com) months before they were printed here. The philosophy that governs the publication of HIV Medicine 2006 has recently been published at www.freemedicalinformation.com. We firmly believe that that is the way medical textbooks should be handled in the 21st century.
Bernd Sebastian Kamps and Christian Hoffmann
The first reports of homosexual patients suffering from previously rare diseases such as pneumocystis pneumonia and Kaposi's sarcoma were published in May 1981 (Centers for Disease Control 1981a, 1981b, 1981c). It soon became clear that the new disease affected other population groups as well, when the first cases were reported in injecting drug users. However, it took almost two years until, in 1983, the human immunodeficiency virus type I (HIV-1) was defined as the primary cause of the acquired immunodeficiency syndrome (Barré-Sinoussi 1983, Broder 1984, Gallo 1984).
Almost 25 years have now elapsed. Twenty-five years, in which HIV infection has changed from a fatal condition to a manageable chronic illness. Twenty-five years, in which the development of antiretroviral therapy (ART) has been one of the dramatic advances in the history of medicine. However, for the vast majority of people living with HIV/AIDS, ART is still light years away - largely inaccessible in resource-poor countries where HIV continues to devastate families, communities and societies, especially the poor and the socially marginalized.
In the following 800 pages, we present a comprehensive overview of the treatment of HIV infection and its complications. As in previous years, all chapters have been thoroughly revised, and most parts of the book were available on the Internet (www.HIVMedicine.com) months before they were printed here. The philosophy that governs the publication of HIV Medicine 2006 has recently been published at www.freemedicalinformation.com. We firmly believe that that is the way medical textbooks should be handled in the 21st century.
Saturday, December 15, 2007
HIV/AIDS DIAGNOSES
HIV/AIDS DIAGNOSES
At the end of 2003, an estimated 1,039,000 to 1,185,000 persons in the United States were living with HIV/AIDS [1].* In 2005, 37,331 cases of HIV/AIDS in adults, adolescents, and children were diagnosed in the 33 states with long-term, confidential name-based HIV reporting [2]. CDC has estimated that approximately 40,000 persons in the United States become infected with HIV each year [3].
By Transmission Category
In 2005, the largest estimated proportion of HIV/AIDS diagnoses were for men who have sex with men (MSM), followed by adults and adolescents infected through heterosexual contact.
Transmission categories of adults and adolescents
with HIV/AIDS diagnosed during 2005
Transmission categories of adults and adolescents with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
*The term HIV/AIDS refers to 3 categories of diagnoses collectively: (1) a diagnosis of HIV infection (not AIDS), (2) a diagnosis of HIV infection with a later diagnosis of AIDS, and (3) concurrent diagnoses of HIV infection and AIDS.
By Sex
In 2005, almost three quarters of HIV/AIDS diagnoses were for male adolescents and adults.
Sex of adults and adolescents with HIV/AIDS
diagnosed during 2005
Sex of adults and adolescents with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
By Race/Ethnicity
In 2005, blacks (including African Americans), who make up approximately 13% of the US population, accounted for almost half of the estimated number of HIV/AIDS cases diagnosed.
Race/ethnicity of persons (including children) with
HIV/AIDS diagnosed during 2005
Race/ethnicity of persons (including children) with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
TRENDS IN AIDS DIAGNOSES AND DEATHS
During the mid-to-late 1990s, advances in treatment slowed the progression of HIV infection to AIDS and led to dramatic decreases in deaths among persons with AIDS. The number of deaths of persons with AIDS fluctuated from 2001 through 2005, but the number of AIDS cases diagnosed during that same period increased [2]. The reasons for the increase in the number of AIDS diagnoses are unclear but may be due to increased emphasis on testing; the fact that more people are living with HIV and thus are experiencing the development of AIDS; and technical issues in the statistical process used in estimating the number of AIDS diagnoses.
Better treatments have also led to an increase in the number of persons in the 50 states and the District of Columbia (D.C.) who are living with AIDS. From 2001 through 2005, the estimated number of persons in the 50 states and D.C. living with AIDS increased from 331,482 to 421,873—an increase of 27% [2].
Estimated numbers of AIDS diagnoses, deaths, and persons living with AIDS, 2001–2005
spacer 2001 spacer 2002 spacer 2003 spacer 2004 spacer 2005 spacer Cumulative
(1981-2005)
AIDS diagnoses spacer 38,079 spacer 38,408 spacer 39,666 spacer 39,524 spacer 40,608 spacer 952,629
spacer
Deaths of persons with AIDS spacer 16,980 spacer 16,641 spacer 17,404 spacer 17,453 spacer 16,316 spacer 530,756
spacer
Persons living with AIDS spacer 331,482 spacer 353,249 spacer 375,511 spacer 397,582 spacer 421,873 spacer NA
At the end of 2003, an estimated 1,039,000 to 1,185,000 persons in the United States were living with HIV/AIDS [1].* In 2005, 37,331 cases of HIV/AIDS in adults, adolescents, and children were diagnosed in the 33 states with long-term, confidential name-based HIV reporting [2]. CDC has estimated that approximately 40,000 persons in the United States become infected with HIV each year [3].
By Transmission Category
In 2005, the largest estimated proportion of HIV/AIDS diagnoses were for men who have sex with men (MSM), followed by adults and adolescents infected through heterosexual contact.
Transmission categories of adults and adolescents
with HIV/AIDS diagnosed during 2005
Transmission categories of adults and adolescents with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
*The term HIV/AIDS refers to 3 categories of diagnoses collectively: (1) a diagnosis of HIV infection (not AIDS), (2) a diagnosis of HIV infection with a later diagnosis of AIDS, and (3) concurrent diagnoses of HIV infection and AIDS.
By Sex
In 2005, almost three quarters of HIV/AIDS diagnoses were for male adolescents and adults.
Sex of adults and adolescents with HIV/AIDS
diagnosed during 2005
Sex of adults and adolescents with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
By Race/Ethnicity
In 2005, blacks (including African Americans), who make up approximately 13% of the US population, accounted for almost half of the estimated number of HIV/AIDS cases diagnosed.
Race/ethnicity of persons (including children) with
HIV/AIDS diagnosed during 2005
Race/ethnicity of persons (including children) with HIV/AIDS diagnosed during 2005
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting.
TRENDS IN AIDS DIAGNOSES AND DEATHS
During the mid-to-late 1990s, advances in treatment slowed the progression of HIV infection to AIDS and led to dramatic decreases in deaths among persons with AIDS. The number of deaths of persons with AIDS fluctuated from 2001 through 2005, but the number of AIDS cases diagnosed during that same period increased [2]. The reasons for the increase in the number of AIDS diagnoses are unclear but may be due to increased emphasis on testing; the fact that more people are living with HIV and thus are experiencing the development of AIDS; and technical issues in the statistical process used in estimating the number of AIDS diagnoses.
Better treatments have also led to an increase in the number of persons in the 50 states and the District of Columbia (D.C.) who are living with AIDS. From 2001 through 2005, the estimated number of persons in the 50 states and D.C. living with AIDS increased from 331,482 to 421,873—an increase of 27% [2].
Estimated numbers of AIDS diagnoses, deaths, and persons living with AIDS, 2001–2005
spacer 2001 spacer 2002 spacer 2003 spacer 2004 spacer 2005 spacer Cumulative
(1981-2005)
AIDS diagnoses spacer 38,079 spacer 38,408 spacer 39,666 spacer 39,524 spacer 40,608 spacer 952,629
spacer
Deaths of persons with AIDS spacer 16,980 spacer 16,641 spacer 17,404 spacer 17,453 spacer 16,316 spacer 530,756
spacer
Persons living with AIDS spacer 331,482 spacer 353,249 spacer 375,511 spacer 397,582 spacer 421,873 spacer NA
Federal HIV treatment guidelines updated
Federal HIV treatment guidelines updated
Important shifts noted for when and how to treat HIV disease.
The guidelines are developed by a panel of physicians, researchers and community members who review and interpret current science to develop treatment recommendations. The most notable change in this revision reflects the recommendation of starting treatment earlier for people living with HIV. For more information, read the article.
Merck vaccine study fails
Immunizations are stopped in two HIV vaccine studies.
The large international STEP vaccine study of 3,000 individuals has shown poor results. Experts recommended its closure. For more information, see In the news.
Join Hepatitis C Advocates UNITED!
Project Inform expands advocacy work to include hepatitis C.
Over 4 million Americans currently are infected with the hepatitis C virus. Most are unaware that they have the virus. Nearly 225,000 also live with HIV. The new HCAU is meeting the challenge for improved funding for viral hepatitis programs.
logo: until there's a cure
Under One Roof to launch holiday event
Project Inform will benefit from this year's “A Home for the Holidays”.
Under One Roof will launch a different kind of holiday store and event center located at 2278 Market Street (the old Tower Video). Read more info on the event.
logo: under one roof
Academy Awards Gala
February 24, 2008, Fort Mason, San Francisco
Project Inform announced as a beneficiary of 2008 gala.
For 28 years, this annual Gala and monthly events have raised over $6.5 million to support 60 HIV/AIDS service organizations within the San Francisco Bay Area. Read more info on this upcoming event.
logo: academy of friends
Evening of Hope 2007
Event is a resounding success.
For a recap of Project Inform's annual event, see the events p
Important shifts noted for when and how to treat HIV disease.
The guidelines are developed by a panel of physicians, researchers and community members who review and interpret current science to develop treatment recommendations. The most notable change in this revision reflects the recommendation of starting treatment earlier for people living with HIV. For more information, read the article.
Merck vaccine study fails
Immunizations are stopped in two HIV vaccine studies.
The large international STEP vaccine study of 3,000 individuals has shown poor results. Experts recommended its closure. For more information, see In the news.
Join Hepatitis C Advocates UNITED!
Project Inform expands advocacy work to include hepatitis C.
Over 4 million Americans currently are infected with the hepatitis C virus. Most are unaware that they have the virus. Nearly 225,000 also live with HIV. The new HCAU is meeting the challenge for improved funding for viral hepatitis programs.
logo: until there's a cure
Under One Roof to launch holiday event
Project Inform will benefit from this year's “A Home for the Holidays”.
Under One Roof will launch a different kind of holiday store and event center located at 2278 Market Street (the old Tower Video). Read more info on the event.
logo: under one roof
Academy Awards Gala
February 24, 2008, Fort Mason, San Francisco
Project Inform announced as a beneficiary of 2008 gala.
For 28 years, this annual Gala and monthly events have raised over $6.5 million to support 60 HIV/AIDS service organizations within the San Francisco Bay Area. Read more info on this upcoming event.
logo: academy of friends
Evening of Hope 2007
Event is a resounding success.
For a recap of Project Inform's annual event, see the events p
Thursday, December 13, 2007
REFERENCES
REFERENCES
* CDC. HIV/AIDS Surveillance Report, 2005. Vol. 17. Rev ed. Atlanta: US Department of Health and Human Services, CDC: 2007:1–46. Accessed June 28, 2007.
* Binson D, Michaels S, Stall R, et al. Prevalence and social distribution of men who have sex with men: United States and its urban centers. Journal of Sex Research 1995;32:245–254.
* CDC. Increases in HIV diagnoses–29 states, 1999–2002. MMWR 2003;52:1145–1148.
* CDC. Trends in HIV/AIDS diagnoses―33 states, 2001–2004. MMWR 2005;54:1149–1153.
* CDC. HIV prevalence, unrecognized infection, and HIV testing among men who have sex with men―five US cities, June 2004–April 2005. MMWR 2005;54:597–601.
* Mansergh G, Marks G, Colfax GN, et al. “Barebacking” in a diverse sample of men who have sex with men. AIDS 2002;16:653–659.
* Wolitski R. The emergence of barebacking among gay men in the United States: a public health perspective. Journal of Gay and Lesbian Psychotherapy 2005;9:13–38.
* Truong H-H, Kellogg T, Klausner JD, et al. Increases in sexually transmitted infections and sexual risk behaviour without a concurrent increase in HIV incidence among men who have sex with men in San Francisco: a suggestion of serosorting? Sexually Transmitted Infections 2006:82;461–466.
* CDC. Special focus profiles: men who have sex with men. In Sexually Transmitted Disease Surveillance, 2005. Atlanta: US Department of Health and Human Services, CDC; November 2006. Accessed May 14, 2007.
* CDC. Primary and Secondary Syphilis Among Men Who Have Sex with Men --- New York City, 2001. MMWR 2002;51:853–856.
* CDC. Primary and secondary syphilis―United States, 1999. MMWR 2001;50:113–117. MMWR 2001;50:113–117.
* CDC. Transmission of Primary and Secondary Syphilis by Oral Sex --- Chicago, Illinois, 1998--2002. MMWR 2004;53:966–968.
* CDC. Trends in Primary and Secondary Syphilis and HIV Infections in Men Who Have Sex with Men --- San Francisco and Los Angeles, California, 1998--2002. MMWR 2004;53:575–578.
* Glynn M, Rhodes P. Estimated HIV prevalence in the United States at the end of 2003. National HIV Prevention Conference; June 2005; Atlanta. Abstract T1-B1101.
* MacKellar DA, Valleroy L, Secura G, et al. Unrecognized HIV infection, risk behaviors, and perceptions of risk among young men who have sex with men: opportunities for advancing HIV prevention in the third decade of HIV/AIDS. Journal of Acquired Immune Deficiency Syndromes 2005;38:603–614.
* Weinhardt LS, Carey MP, Johnson BT, Bickham NL. Effects of HIV counseling and testing on sexual risk behavior: a meta-analytic review of published research, 1985–1997. American Journal of Public Health 1999;89:1397–1405.
* CDC. High-risk sexual behavior by HIV-positive men who have sex with men―16 sites, United States, 2000–2002. MMWR 2004;53:891–894.
* Stall R, Paul JP, Greenwood G, et al. Alcohol use, drug use and alcohol-related problems among men who have sex with men: the Urban Men’s Health Study. Addiction 2001;96:1589–1601.
* CDC. Methamphetamine and HIV risk among men who have sex with men [fact sheet]. Available at http://www.effectiveinterventions.orgNon-CDC Web Link. Accessed May 15, 2007.
* Mansergh G, Colfax GN, Marks G, et al. The Circuit Party Men’s Health Survey: findings and implications for gay and bisexual men. American Journal of Public Health 2001;91:953–958.
* Purcell DW, Parsons JT, Halkitis PN, Mizuno Y, Woods WJ. Substance use and sexual transmission risk behavior of HIV-positive men who have sex with men. Journal of Substance Abuse 2001;13:185–200.
* Suarez T, Miller J. Negotiating risks in context: a perspective on unprotected anal intercourse and barebacking among men who have sex with men―where do we go from here? Archives of Sexual Behavior 2001;30:287–300.
* Ostrow DG, Fox K, Chmiel JS, et al. Attitudes towards highly active antiretroviral therapy predict sexual risk taking among HIV-infected and uninfected gay men in the Multicenter AIDS Cohort Study (MACS). XIII International Conference on AIDS; July 2000; Durban, South Africa. Abstract ThOrC719.
Available at http://www.iac2000.orgNon-CDC Web Link. Accessed May 15, 2007.
* Stolte IG, Dukers NHTM, de Wit JBF, et al. Increases in STDs among men who have sex with men (MSM) and in risk behavior among HIV-positive MSM in Amsterdam, possibly related to HAART-induced immunologic and virologic improvements. Conference on Retroviruses and Opportunistic Infections; February 2001; Chicago. Abstract 261. Available at http://www.retroconference.org/2001/abstracts/
Abstracts/Abstracts/261.htmNon-CDC Web Link. Accessed May 15, 2007.
* Kelly JA, Hoffman RG, Rompa D, Gray M. Protease inhibitor combination therapies and perceptions of gay men regarding AIDS severity and the need to maintain safer sex. AIDS 1998;12:F91–F95.
* Dilley J, Wood W, MacFarland W. Are advances in treatment changing views about high-risk sex? New England Journal of Medicine 1997;337:501–502.
* Crepaz N, Hart TA, Marks G. Highly active antiretroviral therapy and sexual risk behavior: a meta-analytic review. JAMA 2004;292:224–236.
* McAuliffe T, Kelly J, Sikkema K. Sexual HIV risk behavior levels among young and older gay men outside of AIDS epicenters: findings of a 16-city sample. AIDS and Behavior 1999;3:111–119.
* Mansergh G, Marks G. Age and risk of HIV infection in men who have sex with men. AIDS 1998;12:1119–1128.
* Wolitski RJ, Bailey CJ, O’Leary A, Gómez DA, Parsons JT, for the Seropositive Urban Men’s Study Group (SUMS). Self-perceived responsibility of HIV-seropositive men who have sex with men for preventing HIV transmission. AIDS and Behavior 2003;7:363–372.
* Wolitski RJ, Parsons JT, Gómez CA, for the SUMS and SUMIT Study Teams. Prevention with HIV-seropositive men who have sex with men: lessons learned from the Seropositive Urban Men’s Study (SUMS) and the Seropositive Urban Men’s Intervention Trial (SUMIT). Journal of Acquired Immune Deficiency Syndromes 2004;37(suppl 2):S101–S109.
* Denning PH, Campsmith ML. Unprotected anal intercourse among HIV-positive men who have a steady male sex partner with negative or unknown HIV serostatus. American Journal of Public Health 2005;95:152–158.
* Crepaz N, Lyles CM, Wolitski RJ, et al. Do prevention interventions reduce HIV risk behaviours among people living with HIV? A meta-analytic review of controlled trials. AIDS 2006;20:143–157.
* Johnson BT, Carey MP, Chaudoir SR, et al. Sexual risk reduction for person living with HIV: research synthesis of randomized controlled trials, 1993 to 2004. Journal of Acquired Immune Deficiency Syndromes 2006;41:642–650.
* CDC. Internet Use and Early Syphilis Infection Among Men Who Have Sex with Men --- San Francisco, California, 1999--2003. MMWR 2003;52:1229–1232.
* Bull SS, McFarlane M. Soliciting sex on the Internet: what are the risks for sexually transmitted diseases and HIV? Sexually Transmitted Diseases 2000;27:545–550.
* CDC. Late Versus Early Testing of HIV --- 16 Sites, United States, 2000--2003. MMWR 2003;52:582–586.CDC.
* CDC. HIV/AIDS Among Racial/Ethnic Minority Men Who Have Sex with Men -- United States, 1989-1998. MMWR 2000;49:4–11.
* CDC. HIV Transmission Among Black College Student and Non-Student Men Who Have Sex With Men --- North Carolina, 2003. MMWR 2004;53:731–734.
* Millet G, Malebranche D, Mason B, Spikes P. Focusing “down low”: bisexual black men, HIV risk and heterosexual transmission. Journal of the National Medical Association 2005; 97(7):52S-59S.
* Millet GA, Peterson JL, Wolitski RJ, Stall R. Greater risk for HIV infection of black men who have sex with men: a critical literature review. American Journal of Public Health 2006;96:1007–1019
* Mills TC, Stall R, Pollack L. Health-related characteristics of men who have sex with men: a comparison of those living in “gay ghettos” with those living elsewhere. American Journal of Public Health 2001;91:980–983.
* Diaz R. Latino gay men and psycho-cultural barriers to AIDS prevention. In: Levin MP, Nardi PM, Gagnon JH, eds. Changing Times: Gay Men and Lesbians Encounter HIV/AIDS. Chicago: University of Chicago Press; 1997.
* Marín G, Marín BV. Research with Hispanic Populations. Vol. 23. Newbury Park, CA: Sage; 1991. Research Methods Series.
* Kelly JJ, Chu SY, Diaz T, et al. Race/ethnicity misclassification of persons reported with AIDS. Ethnicity and Health 1996;1:87–94.
* Fenton KA, Imrie J. Increasing rates of sexually transmitted diseases in homosexual men in Western Europe and the United States: why? Infectious Disease Clinics of North America 2005;19:311–331.
* Stall R, Mills TC, Williamson J, et al. Associations of co-occurring psychosocial health problems and increased vulnerability to HIV/AIDS among urban men who have sex with men. American Journal of Public Health 2003;93:939–942.
* Bartholow BN, Goli V, Ackers M, et al. Demographic and behavioral contextual risk groups among men who have sex with men participating in a phase 3 HIV vaccine efficacy trial: implications for HIV prevention and behavioral/biomedical intervention trials. Journal of Acquired Immune Deficiency Syndromes 2006; 43:594–602.
* CDC. Sexually transmitted diseases treatment guidelines, 2006 [corrections published in MMWR 2006;55(36):997]. MMWR 2006;55(RR-11). Accessed May 15, 2007.
* Johnson WD, Hedges LV, Ramirez G, et al. HIV prevention research for men who have sex with men: a systematic review and meta-analysis. Journal of Acquired Immune Deficiency Syndromes 2002;30(suppl 1):S118–S129.
* CDC. HIV/AIDS Surveillance Report, 2005. Vol. 17. Rev ed. Atlanta: US Department of Health and Human Services, CDC: 2007:1–46. Accessed June 28, 2007.
* Binson D, Michaels S, Stall R, et al. Prevalence and social distribution of men who have sex with men: United States and its urban centers. Journal of Sex Research 1995;32:245–254.
* CDC. Increases in HIV diagnoses–29 states, 1999–2002. MMWR 2003;52:1145–1148.
* CDC. Trends in HIV/AIDS diagnoses―33 states, 2001–2004. MMWR 2005;54:1149–1153.
* CDC. HIV prevalence, unrecognized infection, and HIV testing among men who have sex with men―five US cities, June 2004–April 2005. MMWR 2005;54:597–601.
* Mansergh G, Marks G, Colfax GN, et al. “Barebacking” in a diverse sample of men who have sex with men. AIDS 2002;16:653–659.
* Wolitski R. The emergence of barebacking among gay men in the United States: a public health perspective. Journal of Gay and Lesbian Psychotherapy 2005;9:13–38.
* Truong H-H, Kellogg T, Klausner JD, et al. Increases in sexually transmitted infections and sexual risk behaviour without a concurrent increase in HIV incidence among men who have sex with men in San Francisco: a suggestion of serosorting? Sexually Transmitted Infections 2006:82;461–466.
* CDC. Special focus profiles: men who have sex with men. In Sexually Transmitted Disease Surveillance, 2005. Atlanta: US Department of Health and Human Services, CDC; November 2006. Accessed May 14, 2007.
* CDC. Primary and Secondary Syphilis Among Men Who Have Sex with Men --- New York City, 2001. MMWR 2002;51:853–856.
* CDC. Primary and secondary syphilis―United States, 1999. MMWR 2001;50:113–117. MMWR 2001;50:113–117.
* CDC. Transmission of Primary and Secondary Syphilis by Oral Sex --- Chicago, Illinois, 1998--2002. MMWR 2004;53:966–968.
* CDC. Trends in Primary and Secondary Syphilis and HIV Infections in Men Who Have Sex with Men --- San Francisco and Los Angeles, California, 1998--2002. MMWR 2004;53:575–578.
* Glynn M, Rhodes P. Estimated HIV prevalence in the United States at the end of 2003. National HIV Prevention Conference; June 2005; Atlanta. Abstract T1-B1101.
* MacKellar DA, Valleroy L, Secura G, et al. Unrecognized HIV infection, risk behaviors, and perceptions of risk among young men who have sex with men: opportunities for advancing HIV prevention in the third decade of HIV/AIDS. Journal of Acquired Immune Deficiency Syndromes 2005;38:603–614.
* Weinhardt LS, Carey MP, Johnson BT, Bickham NL. Effects of HIV counseling and testing on sexual risk behavior: a meta-analytic review of published research, 1985–1997. American Journal of Public Health 1999;89:1397–1405.
* CDC. High-risk sexual behavior by HIV-positive men who have sex with men―16 sites, United States, 2000–2002. MMWR 2004;53:891–894.
* Stall R, Paul JP, Greenwood G, et al. Alcohol use, drug use and alcohol-related problems among men who have sex with men: the Urban Men’s Health Study. Addiction 2001;96:1589–1601.
* CDC. Methamphetamine and HIV risk among men who have sex with men [fact sheet]. Available at http://www.effectiveinterventions.orgNon-CDC Web Link. Accessed May 15, 2007.
* Mansergh G, Colfax GN, Marks G, et al. The Circuit Party Men’s Health Survey: findings and implications for gay and bisexual men. American Journal of Public Health 2001;91:953–958.
* Purcell DW, Parsons JT, Halkitis PN, Mizuno Y, Woods WJ. Substance use and sexual transmission risk behavior of HIV-positive men who have sex with men. Journal of Substance Abuse 2001;13:185–200.
* Suarez T, Miller J. Negotiating risks in context: a perspective on unprotected anal intercourse and barebacking among men who have sex with men―where do we go from here? Archives of Sexual Behavior 2001;30:287–300.
* Ostrow DG, Fox K, Chmiel JS, et al. Attitudes towards highly active antiretroviral therapy predict sexual risk taking among HIV-infected and uninfected gay men in the Multicenter AIDS Cohort Study (MACS). XIII International Conference on AIDS; July 2000; Durban, South Africa. Abstract ThOrC719.
Available at http://www.iac2000.orgNon-CDC Web Link. Accessed May 15, 2007.
* Stolte IG, Dukers NHTM, de Wit JBF, et al. Increases in STDs among men who have sex with men (MSM) and in risk behavior among HIV-positive MSM in Amsterdam, possibly related to HAART-induced immunologic and virologic improvements. Conference on Retroviruses and Opportunistic Infections; February 2001; Chicago. Abstract 261. Available at http://www.retroconference.org/2001/abstracts/
Abstracts/Abstracts/261.htmNon-CDC Web Link. Accessed May 15, 2007.
* Kelly JA, Hoffman RG, Rompa D, Gray M. Protease inhibitor combination therapies and perceptions of gay men regarding AIDS severity and the need to maintain safer sex. AIDS 1998;12:F91–F95.
* Dilley J, Wood W, MacFarland W. Are advances in treatment changing views about high-risk sex? New England Journal of Medicine 1997;337:501–502.
* Crepaz N, Hart TA, Marks G. Highly active antiretroviral therapy and sexual risk behavior: a meta-analytic review. JAMA 2004;292:224–236.
* McAuliffe T, Kelly J, Sikkema K. Sexual HIV risk behavior levels among young and older gay men outside of AIDS epicenters: findings of a 16-city sample. AIDS and Behavior 1999;3:111–119.
* Mansergh G, Marks G. Age and risk of HIV infection in men who have sex with men. AIDS 1998;12:1119–1128.
* Wolitski RJ, Bailey CJ, O’Leary A, Gómez DA, Parsons JT, for the Seropositive Urban Men’s Study Group (SUMS). Self-perceived responsibility of HIV-seropositive men who have sex with men for preventing HIV transmission. AIDS and Behavior 2003;7:363–372.
* Wolitski RJ, Parsons JT, Gómez CA, for the SUMS and SUMIT Study Teams. Prevention with HIV-seropositive men who have sex with men: lessons learned from the Seropositive Urban Men’s Study (SUMS) and the Seropositive Urban Men’s Intervention Trial (SUMIT). Journal of Acquired Immune Deficiency Syndromes 2004;37(suppl 2):S101–S109.
* Denning PH, Campsmith ML. Unprotected anal intercourse among HIV-positive men who have a steady male sex partner with negative or unknown HIV serostatus. American Journal of Public Health 2005;95:152–158.
* Crepaz N, Lyles CM, Wolitski RJ, et al. Do prevention interventions reduce HIV risk behaviours among people living with HIV? A meta-analytic review of controlled trials. AIDS 2006;20:143–157.
* Johnson BT, Carey MP, Chaudoir SR, et al. Sexual risk reduction for person living with HIV: research synthesis of randomized controlled trials, 1993 to 2004. Journal of Acquired Immune Deficiency Syndromes 2006;41:642–650.
* CDC. Internet Use and Early Syphilis Infection Among Men Who Have Sex with Men --- San Francisco, California, 1999--2003. MMWR 2003;52:1229–1232.
* Bull SS, McFarlane M. Soliciting sex on the Internet: what are the risks for sexually transmitted diseases and HIV? Sexually Transmitted Diseases 2000;27:545–550.
* CDC. Late Versus Early Testing of HIV --- 16 Sites, United States, 2000--2003. MMWR 2003;52:582–586.CDC.
* CDC. HIV/AIDS Among Racial/Ethnic Minority Men Who Have Sex with Men -- United States, 1989-1998. MMWR 2000;49:4–11.
* CDC. HIV Transmission Among Black College Student and Non-Student Men Who Have Sex With Men --- North Carolina, 2003. MMWR 2004;53:731–734.
* Millet G, Malebranche D, Mason B, Spikes P. Focusing “down low”: bisexual black men, HIV risk and heterosexual transmission. Journal of the National Medical Association 2005; 97(7):52S-59S.
* Millet GA, Peterson JL, Wolitski RJ, Stall R. Greater risk for HIV infection of black men who have sex with men: a critical literature review. American Journal of Public Health 2006;96:1007–1019
* Mills TC, Stall R, Pollack L. Health-related characteristics of men who have sex with men: a comparison of those living in “gay ghettos” with those living elsewhere. American Journal of Public Health 2001;91:980–983.
* Diaz R. Latino gay men and psycho-cultural barriers to AIDS prevention. In: Levin MP, Nardi PM, Gagnon JH, eds. Changing Times: Gay Men and Lesbians Encounter HIV/AIDS. Chicago: University of Chicago Press; 1997.
* Marín G, Marín BV. Research with Hispanic Populations. Vol. 23. Newbury Park, CA: Sage; 1991. Research Methods Series.
* Kelly JJ, Chu SY, Diaz T, et al. Race/ethnicity misclassification of persons reported with AIDS. Ethnicity and Health 1996;1:87–94.
* Fenton KA, Imrie J. Increasing rates of sexually transmitted diseases in homosexual men in Western Europe and the United States: why? Infectious Disease Clinics of North America 2005;19:311–331.
* Stall R, Mills TC, Williamson J, et al. Associations of co-occurring psychosocial health problems and increased vulnerability to HIV/AIDS among urban men who have sex with men. American Journal of Public Health 2003;93:939–942.
* Bartholow BN, Goli V, Ackers M, et al. Demographic and behavioral contextual risk groups among men who have sex with men participating in a phase 3 HIV vaccine efficacy trial: implications for HIV prevention and behavioral/biomedical intervention trials. Journal of Acquired Immune Deficiency Syndromes 2006; 43:594–602.
* CDC. Sexually transmitted diseases treatment guidelines, 2006 [corrections published in MMWR 2006;55(36):997]. MMWR 2006;55(RR-11). Accessed May 15, 2007.
* Johnson WD, Hedges LV, Ramirez G, et al. HIV prevention research for men who have sex with men: a systematic review and meta-analysis. Journal of Acquired Immune Deficiency Syndromes 2002;30(suppl 1):S118–S129.
Understanding HIV and AIDS Data
Understanding HIV and AIDS Data
AIDS surveillance: Through a uniform system, CDC receives reports of AIDS cases from all US states and dependent areas. Since the beginning of the epidemic, these data have been used to monitor trends because they are representative of all areas. The data are statistically adjusted for reporting delays and for the redistribution of cases initially reported without risk factors. As treatment has become more available, trends in new AIDS diagnoses no longer accurately represent trends in new HIV infections; these data now represent persons who are tested late in the course of HIV infection, who have limited access to care, or in whom treatment has failed.
HIV surveillance: Monitoring trends in the HIV epidemic today requires collecting information on HIV cases that have not progressed to AIDS. Areas with confidential name-based HIV infection reporting requirements use the same uniform system for data collection on HIV cases as for AIDS cases. A total of 33 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming) have collected these data for at least 5 years, providing sufficient data to monitor HIV trends and to estimate risk behaviors for HIV infection.
HIV/AIDS: This term is used to refer to 3 categories of diagnoses collectively: (1) a diagnosis of HIV infection (not AIDS), (2) a diagnosis of HIV infection and a later diagnosis of AIDS, and (3) concurrent diagnoses of HIV infection and AIDS.
AIDS surveillance: Through a uniform system, CDC receives reports of AIDS cases from all US states and dependent areas. Since the beginning of the epidemic, these data have been used to monitor trends because they are representative of all areas. The data are statistically adjusted for reporting delays and for the redistribution of cases initially reported without risk factors. As treatment has become more available, trends in new AIDS diagnoses no longer accurately represent trends in new HIV infections; these data now represent persons who are tested late in the course of HIV infection, who have limited access to care, or in whom treatment has failed.
HIV surveillance: Monitoring trends in the HIV epidemic today requires collecting information on HIV cases that have not progressed to AIDS. Areas with confidential name-based HIV infection reporting requirements use the same uniform system for data collection on HIV cases as for AIDS cases. A total of 33 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Florida, Idaho, Indiana, Iowa, Kansas, Louisiana, Michigan, Minnesota, Mississippi, Missouri, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, West Virginia, Wisconsin, and Wyoming) have collected these data for at least 5 years, providing sufficient data to monitor HIV trends and to estimate risk behaviors for HIV infection.
HIV/AIDS: This term is used to refer to 3 categories of diagnoses collectively: (1) a diagnosis of HIV infection (not AIDS), (2) a diagnosis of HIV infection and a later diagnosis of AIDS, and (3) concurrent diagnoses of HIV infection and AIDS.
PREVENTION
PREVENTION
To reduce the incidence of HIV, CDC released the Revised Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care Settings in 2006. These recommendations include the routine HIV screening of adults, adolescents, and pregnant women in health care settings in the United States. They also include reducing barriers to HIV testing. In 2003, CDC announced Advancing HIV Prevention. This initiative comprises 4 strategies: making HIV testing a routine part of medical care, implementing new models for diagnosing HIV infections outside medical settings, preventing new infections by working with HIV-infected persons and their partners, and further decreasing perinatal HIV transmission.
Given that a large number of HIV-infected MSM are unaware of their infection, HIV testing is an important strategy for this population. Many of these men have previously tested HIV-negative, so CDC recommends that all sexually active MSM be tested for HIV at least once a year [49]. MSM who engage in high-risk behaviors (e.g., unprotected anal sex with casual partners) should be tested more frequently.
MSM as a group continues to be the population most affected by HIV infection and AIDS. Howver, research shows that HIV prevention efforts can reduce sexual risk factors: one review found that among men who received an HIV prevention intervention, the proportion who engaged in unprotected sex decreased, on average, 26% [50].
CDC offers effective interventions for MSM (http://www.effectiveinterventions.org)Non-CDC Web Link. These interventions can be tailored to various audiences, such as African American or Hispanic MSM. For example,
* Many Men, Many Voices, which is a group STD/HIV prevention intervention for gay men of color and men who have sex with other men but do not identify themselves as gay or bisexual
* Mpowerment, which comprises HIV prevention, safer sex, and risk-reduction messages in a community-building format for young MSM
* Popular Opinion Leader, which involves identifying, enlisting, and training key opinion leaders to encourage safer sex as the norm in the social networks of MSM
* Healthy Relationships, which helps develop the skills and self-efficacy of MSM and other people living with HIV/AIDS
* Peers Reaching Out and Modeling Intervention Strategies (PROMISE), which uses peer advocates (including men who do not identify themselves as gay) to help people adopt practices to reduce or eliminate risk factors for HIV infection
In 2006, CDC provided 54 awards to community-based organizations that focus primarily on MSM. CDC also provides funding through state, territorial, and local health departments. Of these 54 awards, 63% focus on African Americans, 43% on Hispanics, 13% on Asians and Pacific Islanders, and 20% on whites (the percentages do not add to 100% because some of the organizations focus on more than one racial/ethnic group). For example,
* An organization in Jefferson County, Alabama, that provides a range of services, including individual counseling, community and street outreach, and interventions for African American men and Spanish-speaking men
* An organization in New York City that provides HIV/AIDS–related services, education, and research to Asian and Pacific Islander communities
* An organization offering HIV/AIDS services throughout Los Angeles and San Bernardino counties and San Diego that is committed to enhancing the health and well-being of the Latino community and other underserved communities through community education, prevention, mobilization, advocacy, and direct social services.
To reduce the incidence of HIV, CDC released the Revised Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care Settings in 2006. These recommendations include the routine HIV screening of adults, adolescents, and pregnant women in health care settings in the United States. They also include reducing barriers to HIV testing. In 2003, CDC announced Advancing HIV Prevention. This initiative comprises 4 strategies: making HIV testing a routine part of medical care, implementing new models for diagnosing HIV infections outside medical settings, preventing new infections by working with HIV-infected persons and their partners, and further decreasing perinatal HIV transmission.
Given that a large number of HIV-infected MSM are unaware of their infection, HIV testing is an important strategy for this population. Many of these men have previously tested HIV-negative, so CDC recommends that all sexually active MSM be tested for HIV at least once a year [49]. MSM who engage in high-risk behaviors (e.g., unprotected anal sex with casual partners) should be tested more frequently.
MSM as a group continues to be the population most affected by HIV infection and AIDS. Howver, research shows that HIV prevention efforts can reduce sexual risk factors: one review found that among men who received an HIV prevention intervention, the proportion who engaged in unprotected sex decreased, on average, 26% [50].
CDC offers effective interventions for MSM (http://www.effectiveinterventions.org)Non-CDC Web Link. These interventions can be tailored to various audiences, such as African American or Hispanic MSM. For example,
* Many Men, Many Voices, which is a group STD/HIV prevention intervention for gay men of color and men who have sex with other men but do not identify themselves as gay or bisexual
* Mpowerment, which comprises HIV prevention, safer sex, and risk-reduction messages in a community-building format for young MSM
* Popular Opinion Leader, which involves identifying, enlisting, and training key opinion leaders to encourage safer sex as the norm in the social networks of MSM
* Healthy Relationships, which helps develop the skills and self-efficacy of MSM and other people living with HIV/AIDS
* Peers Reaching Out and Modeling Intervention Strategies (PROMISE), which uses peer advocates (including men who do not identify themselves as gay) to help people adopt practices to reduce or eliminate risk factors for HIV infection
In 2006, CDC provided 54 awards to community-based organizations that focus primarily on MSM. CDC also provides funding through state, territorial, and local health departments. Of these 54 awards, 63% focus on African Americans, 43% on Hispanics, 13% on Asians and Pacific Islanders, and 20% on whites (the percentages do not add to 100% because some of the organizations focus on more than one racial/ethnic group). For example,
* An organization in Jefferson County, Alabama, that provides a range of services, including individual counseling, community and street outreach, and interventions for African American men and Spanish-speaking men
* An organization in New York City that provides HIV/AIDS–related services, education, and research to Asian and Pacific Islander communities
* An organization offering HIV/AIDS services throughout Los Angeles and San Bernardino counties and San Diego that is committed to enhancing the health and well-being of the Latino community and other underserved communities through community education, prevention, mobilization, advocacy, and direct social services.
RISK FACTORS AND BARRIERS TO PREVENTION
RISK FACTORS AND BARRIERS TO PREVENTION
Sexual Risk Factors
Sexual risk factors account for most HIV infections in MSM. These factors include unprotected sex and sexually transmitted diseases (STDs).
* Having anal sex without a condom continues to be a significant threat to the health of MSM [6]. Unprotected anal sex (barebacking) with casual partners is an increasing concern. Not all the reasons for an apparent increase in unprotected anal intercourse are known, but research points to the following factors: optimism about improved HIV treatment, substance use, complex sexual decision making, seeking sex partners on the Internet, and failure to practice safer sex [7]. Some of these men may be serosorting, or only having sex (or unprotected sex) with a partner whose HIV serostatus, they believe, is the same as their own. Although serosorting between MSM who have tested HIV-positive is likely to prevent new HIV transmission to persons who are not infected, the effectiveness of serosorting between men who have tested HIV-negative has not been established. Serosorting with condom use may further reduce the risk of HIV transmission. However, for men with casual partners, serosorting alone is likely to be less effective than always using condoms because some men do not know or disclose their HIV serostatus [8].
* STDs, which increase the risk for HIV infection, remain an important health issue for MSM. According to the Gonococcal Isolate Surveillance Project, the proportion of gonorrhea-positive test results among MSM increased from 4% in 1988 to 20.2% in 2004 [9]. Rates of syphilis among MSM have increased in some urban areas, including Chicago, New York, San Francisco, and Seattle [10–12]. In the 9 US cities participating in the MSM Prevalence Monitoring Project, the rates of STDs and HIV positivity varied by race and ethnicity but tended to be highest among black and Hispanic MSM [9]. In addition to increasing susceptibility to HIV, STDs are markers for high-risk sexual practices, through which HIV infection can be transmitted [13].
Unknown HIV Serostatus
Approximately 25% of people in the United States who are infected with HIV do not know they are infected [14].
* Through its National HIV Behavioral Surveillance system, CDC found that 25% of the MSM surveyed in 5 large US cities were infected with HIV and 48% of those infected were unaware of their infections [5].
* In a recent CDC study of young MSM, 77% of those who tested HIV-positive mistakenly believed that they were not infected [15]. Young black MSM in this study were more likely to be unaware of their infection―approximately 9 of 10 young black MSM compared with 6 of 10 young white MSM. Of the men who tested positive, most (74%) had previously tested negative for HIV infection, and 59% believed that they were at low or very low risk.
Research has shown that many people who learn that they are infected with HIV alter their behaviors to reduce their risk of transmitting the virus [16, 17]. Therefore, increasing the proportion of people who know their HIV serostatus can help decrease HIV transmission.
Substance Use
The use of alcohol and illegal drugs continues to be prevalent among some MSM and is linked to risk factors for HIV infection and other STDs [18]. Substance use can increase the risk for HIV transmission through the tendency toward risky sexual behaviors while under the influence and through sharing needles or other injection equipment. Reports of increased use of the stimulant drug methamphetamine are also a concern because methamphetamine use has been associated both with risky sexual behaviors for HIV infection and other STDs and with the sharing of injection equipment when the drug is injected [19]. Methamphetamine and other “party” drugs (such as ecstasy, ketamine, and GHB [gamma hydroxybutyrate]) may be used to decrease social inhibitions and enhance sexual experiences [20]. These drugs, along with alcohol and nitrate inhalants (“poppers”), have been strongly associated with risky sexual practices among MSM [21].
Complacency about Risk
More than 25 years into the HIV epidemic, there is evidence of an underestimation of risk, of difficulty in maintaining safer sex practices, and of a need to sustain prevention efforts for all gay and bisexual men.
* The success of highly active antiretroviral therapy (HAART) may have had the unintended consequence of increasing the risk behaviors of some MSM.
o Some research suggests that the perceptions of the negative aspects of HIV infection have been minimized since the introduction of HAART, which has led to a false understanding of what living with HIV means and thus to an increase in risky sexual behaviors [22, 23]. For example, some MSM may mistakenly believe that they or their partners are not infectious when they take antiretroviral medication or when they have low or undetectable viral loads [24].
o Optimism about HIV treatments is associated with a greater willingness to have unprotected anal intercourse [25–27].
* Long-term efforts to practice safer sex present a significant challenge. A 4-city study indicates that years of exposure to prevention messages and long-term efforts to practice safer sex may play a role in the decision of HIV-positive MSM to engage in unprotected anal intercourse [23, 28].
* The rates of risky behaviors are higher among young MSM than among older MSM [28, 29]. Not having seen firsthand the toll of AIDS in the early years of the epidemic, young MSM may be less motivated to practice safer sex.
MSM Who Are HIV-positive
HAART has enabled HIV-infected MSM to live longer. However, HAART’s success means there are more MSM living with HIV who have the potential to transmit the virus to their sex partners. This emphasizes the importance of focusing prevention efforts on those who are living with HIV.
Although many MSM reduce their risk behaviors after learning that they have HIV, most remain sexually active [17]. Most HIV-infected MSM believe that they have a personal responsibility to protect others from HIV, but some engage in risky sexual behaviors that may result in others’ contracting HIV [30–32]. Interventions to reduce the risk for transmission, some of which were tested with MSM, are available for persons living with HIV [33, 34].
The Internet
During the past decade, the Internet has created new opportunities for MSM to meet sex partners [35]. Internet users can anonymously find partners with similar sexual interests without having to leave their residence or having to risk face-to-face rejection if the behaviors they seek are not consistent with safer sex [36]. The Internet may also normalize certain risky behaviors by making others aware of these behaviors and creating new connections between those who engage in them. At the same time, however, the Internet has the potential to be a powerful tool for use with HIV prevention interventions.
Social Discrimination and Cultural Issues
MSM are members of all communities, all races and ethnicities, and all strata of society. To reduce the rate of HIV infection, prevention efforts must be designed with respect for the many differences among MSM and with recognition of the discrimination against MSM and other persons infected with HIV in many parts of the country.
* Social and economic factors, including racism, homophobia, poverty, and lack of access to health care are barriers to HIV prevention services, particularly for MSM of minority races or ethnicities. Black and Hispanic men are more likely than white men to be given a diagnosis of HIV infection in the late stages of infection, often when they already have AIDS, suggesting that they are not accessing testing or health care services through which HIV infection could be diagnosed at an earlier stage [37].
* The stigma associated with homosexuality may inhibit some men from identifying themselves as gay or bisexual, even though they have sex with other men [38, 39]. Some men who have sex with men and with women don’t identify themselves as gay or bisexual [40]. Research among black men has shown that even if these men do not identify themselves as gay or bisexual, they do not engage in risky behavior more often than the men who do identify themselves as gay or bisexual [41]. This research suggests that elevated rates of STDs and undetected or late diagnosis of HIV infection may contribute to higher rates of HIV infection among black MSM.
* Black and Hispanic MSM are less likely than white MSM to live in gay-identified neighborhoods [42]. Therefore, prevention programs directed to gay-identified neighborhoods may not reach these MSM.
* For Hispanic MSM, unique cultural factors may discourage openness about homosexuality: machismo, the high value placed on masculinity; simpatia, the importance of smooth, nonconfrontational relationships; and familismo, the importance of a close relationship with one’s family [43, 44].
* Although Asians/Pacific Islanders and American Indians/Alaska Natives accounted for less than 2% of the AIDS cases in MSM reported nationally during 1989–1998, these groups accounted for noteworthy proportions of cases in certain metropolitan areas [38]. Also, HIV infection among American Indians and Alaska Natives may be underestimated because not all surveillance systems recognize American Indian or Alaska Native as a race/ethnicity [45].
Combinations of Risk Factors
There is growing recognition that combinations of individual, sociocultural, and biomedical factors affect HIV risk behavior among MSM [46]. Childhood sexual abuse, substance use, depression, and partner violence have been shown to increase the practice of risky sexual behaviors. Further research has shown that the combined effects of these problems may be greater than their individual effects [47]. Therefore, MSM with more than 1 of these problems may have additional risk factors for HIV infection. The expansion and wider awareness of this type of research, which shows the additive effect of various psychosocial problems, will result in more precise prevention efforts.
Differences within the MSM Population
Even though MSM constitute a group at risk for HIV, not all MSM are at risk for HIV. Analyzing the context within which individuals of the larger MSM community live and socialize may be a promising method for developing and focusing HIV interventions. A recent large-scale HIV vaccine efficacy trial looked at combinations of demographic characteristics and risk behaviors to help identify MSM at greatest risk [48]. This study of more than 5,000 HIV-negative MSM found that older men with large numbers of sex partners, young men who used “party” drugs, and older men who used nitrate inhalants were most likely to contract HIV.
The appreciation of differences within the MSM community will aid in the development of successful HIV prevention interventions.
Sexual Risk Factors
Sexual risk factors account for most HIV infections in MSM. These factors include unprotected sex and sexually transmitted diseases (STDs).
* Having anal sex without a condom continues to be a significant threat to the health of MSM [6]. Unprotected anal sex (barebacking) with casual partners is an increasing concern. Not all the reasons for an apparent increase in unprotected anal intercourse are known, but research points to the following factors: optimism about improved HIV treatment, substance use, complex sexual decision making, seeking sex partners on the Internet, and failure to practice safer sex [7]. Some of these men may be serosorting, or only having sex (or unprotected sex) with a partner whose HIV serostatus, they believe, is the same as their own. Although serosorting between MSM who have tested HIV-positive is likely to prevent new HIV transmission to persons who are not infected, the effectiveness of serosorting between men who have tested HIV-negative has not been established. Serosorting with condom use may further reduce the risk of HIV transmission. However, for men with casual partners, serosorting alone is likely to be less effective than always using condoms because some men do not know or disclose their HIV serostatus [8].
* STDs, which increase the risk for HIV infection, remain an important health issue for MSM. According to the Gonococcal Isolate Surveillance Project, the proportion of gonorrhea-positive test results among MSM increased from 4% in 1988 to 20.2% in 2004 [9]. Rates of syphilis among MSM have increased in some urban areas, including Chicago, New York, San Francisco, and Seattle [10–12]. In the 9 US cities participating in the MSM Prevalence Monitoring Project, the rates of STDs and HIV positivity varied by race and ethnicity but tended to be highest among black and Hispanic MSM [9]. In addition to increasing susceptibility to HIV, STDs are markers for high-risk sexual practices, through which HIV infection can be transmitted [13].
Unknown HIV Serostatus
Approximately 25% of people in the United States who are infected with HIV do not know they are infected [14].
* Through its National HIV Behavioral Surveillance system, CDC found that 25% of the MSM surveyed in 5 large US cities were infected with HIV and 48% of those infected were unaware of their infections [5].
* In a recent CDC study of young MSM, 77% of those who tested HIV-positive mistakenly believed that they were not infected [15]. Young black MSM in this study were more likely to be unaware of their infection―approximately 9 of 10 young black MSM compared with 6 of 10 young white MSM. Of the men who tested positive, most (74%) had previously tested negative for HIV infection, and 59% believed that they were at low or very low risk.
Research has shown that many people who learn that they are infected with HIV alter their behaviors to reduce their risk of transmitting the virus [16, 17]. Therefore, increasing the proportion of people who know their HIV serostatus can help decrease HIV transmission.
Substance Use
The use of alcohol and illegal drugs continues to be prevalent among some MSM and is linked to risk factors for HIV infection and other STDs [18]. Substance use can increase the risk for HIV transmission through the tendency toward risky sexual behaviors while under the influence and through sharing needles or other injection equipment. Reports of increased use of the stimulant drug methamphetamine are also a concern because methamphetamine use has been associated both with risky sexual behaviors for HIV infection and other STDs and with the sharing of injection equipment when the drug is injected [19]. Methamphetamine and other “party” drugs (such as ecstasy, ketamine, and GHB [gamma hydroxybutyrate]) may be used to decrease social inhibitions and enhance sexual experiences [20]. These drugs, along with alcohol and nitrate inhalants (“poppers”), have been strongly associated with risky sexual practices among MSM [21].
Complacency about Risk
More than 25 years into the HIV epidemic, there is evidence of an underestimation of risk, of difficulty in maintaining safer sex practices, and of a need to sustain prevention efforts for all gay and bisexual men.
* The success of highly active antiretroviral therapy (HAART) may have had the unintended consequence of increasing the risk behaviors of some MSM.
o Some research suggests that the perceptions of the negative aspects of HIV infection have been minimized since the introduction of HAART, which has led to a false understanding of what living with HIV means and thus to an increase in risky sexual behaviors [22, 23]. For example, some MSM may mistakenly believe that they or their partners are not infectious when they take antiretroviral medication or when they have low or undetectable viral loads [24].
o Optimism about HIV treatments is associated with a greater willingness to have unprotected anal intercourse [25–27].
* Long-term efforts to practice safer sex present a significant challenge. A 4-city study indicates that years of exposure to prevention messages and long-term efforts to practice safer sex may play a role in the decision of HIV-positive MSM to engage in unprotected anal intercourse [23, 28].
* The rates of risky behaviors are higher among young MSM than among older MSM [28, 29]. Not having seen firsthand the toll of AIDS in the early years of the epidemic, young MSM may be less motivated to practice safer sex.
MSM Who Are HIV-positive
HAART has enabled HIV-infected MSM to live longer. However, HAART’s success means there are more MSM living with HIV who have the potential to transmit the virus to their sex partners. This emphasizes the importance of focusing prevention efforts on those who are living with HIV.
Although many MSM reduce their risk behaviors after learning that they have HIV, most remain sexually active [17]. Most HIV-infected MSM believe that they have a personal responsibility to protect others from HIV, but some engage in risky sexual behaviors that may result in others’ contracting HIV [30–32]. Interventions to reduce the risk for transmission, some of which were tested with MSM, are available for persons living with HIV [33, 34].
The Internet
During the past decade, the Internet has created new opportunities for MSM to meet sex partners [35]. Internet users can anonymously find partners with similar sexual interests without having to leave their residence or having to risk face-to-face rejection if the behaviors they seek are not consistent with safer sex [36]. The Internet may also normalize certain risky behaviors by making others aware of these behaviors and creating new connections between those who engage in them. At the same time, however, the Internet has the potential to be a powerful tool for use with HIV prevention interventions.
Social Discrimination and Cultural Issues
MSM are members of all communities, all races and ethnicities, and all strata of society. To reduce the rate of HIV infection, prevention efforts must be designed with respect for the many differences among MSM and with recognition of the discrimination against MSM and other persons infected with HIV in many parts of the country.
* Social and economic factors, including racism, homophobia, poverty, and lack of access to health care are barriers to HIV prevention services, particularly for MSM of minority races or ethnicities. Black and Hispanic men are more likely than white men to be given a diagnosis of HIV infection in the late stages of infection, often when they already have AIDS, suggesting that they are not accessing testing or health care services through which HIV infection could be diagnosed at an earlier stage [37].
* The stigma associated with homosexuality may inhibit some men from identifying themselves as gay or bisexual, even though they have sex with other men [38, 39]. Some men who have sex with men and with women don’t identify themselves as gay or bisexual [40]. Research among black men has shown that even if these men do not identify themselves as gay or bisexual, they do not engage in risky behavior more often than the men who do identify themselves as gay or bisexual [41]. This research suggests that elevated rates of STDs and undetected or late diagnosis of HIV infection may contribute to higher rates of HIV infection among black MSM.
* Black and Hispanic MSM are less likely than white MSM to live in gay-identified neighborhoods [42]. Therefore, prevention programs directed to gay-identified neighborhoods may not reach these MSM.
* For Hispanic MSM, unique cultural factors may discourage openness about homosexuality: machismo, the high value placed on masculinity; simpatia, the importance of smooth, nonconfrontational relationships; and familismo, the importance of a close relationship with one’s family [43, 44].
* Although Asians/Pacific Islanders and American Indians/Alaska Natives accounted for less than 2% of the AIDS cases in MSM reported nationally during 1989–1998, these groups accounted for noteworthy proportions of cases in certain metropolitan areas [38]. Also, HIV infection among American Indians and Alaska Natives may be underestimated because not all surveillance systems recognize American Indian or Alaska Native as a race/ethnicity [45].
Combinations of Risk Factors
There is growing recognition that combinations of individual, sociocultural, and biomedical factors affect HIV risk behavior among MSM [46]. Childhood sexual abuse, substance use, depression, and partner violence have been shown to increase the practice of risky sexual behaviors. Further research has shown that the combined effects of these problems may be greater than their individual effects [47]. Therefore, MSM with more than 1 of these problems may have additional risk factors for HIV infection. The expansion and wider awareness of this type of research, which shows the additive effect of various psychosocial problems, will result in more precise prevention efforts.
Differences within the MSM Population
Even though MSM constitute a group at risk for HIV, not all MSM are at risk for HIV. Analyzing the context within which individuals of the larger MSM community live and socialize may be a promising method for developing and focusing HIV interventions. A recent large-scale HIV vaccine efficacy trial looked at combinations of demographic characteristics and risk behaviors to help identify MSM at greatest risk [48]. This study of more than 5,000 HIV-negative MSM found that older men with large numbers of sex partners, young men who used “party” drugs, and older men who used nitrate inhalants were most likely to contract HIV.
The appreciation of differences within the MSM community will aid in the development of successful HIV prevention interventions.
STATISTICS
STATISTICS
HIV/AIDS in 2005
(The following bullets refer to the 33 states with long-term, confidential name-based HIV reporting. See the box, before the References section, for a list of the 33 states.)
* In the 33 states with long-term, confidential name-based HIV reporting, an estimated 19,620 MSM (18,296 MSM and 1,324 MSM who inject drugs) received a diagnosis of HIV/AIDS, accounting for 71% of male adults and adolescents and 53% of all people receiving an HIV/AIDS diagnosis that year [1].
* The number of HIV/AIDS diagnoses among MSM (including MSM who inject drugs) increased 11% from 2001 through 2005 [1]. It is not known whether this increase is due to an increase in the testing of persons with risk factors, which results in more HIV diagnoses, or due to an increase in cases of HIV infection
* An estimated 231,893 MSM (207,810 MSM and 24,083 MSM who inject drugs) were living with HIV/AIDS [1].
Transmission categories of male adults and adolescents with HIV/AIDS diagnosed during 2005
No. = 27,455 Male-to-male sexual contact: 67% High-risk heterosexual contact: 15% Injection drug use: 13% Male-to-male sexual contact and injection drug use: 5% Other: <1%
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting. Because of rounding, percentages may not equal 100.
Race/ethnicity of MSM living with HIV/AIDS, 2005
MSM; No. = 207,810 White: 50% Black: 32% Hispanic: 16% Asian/Pacific Islander: 1% American Indian/Alaska Native: <1%
MSM who inject drugs; No. = 24,083 White: 45% Black: 39% Hispanic: 14% Asian/Pacific Islander: <1% American Indian/Alaska Native: 1%
Note. Based on 33 states with long-term, confidential name-based HIV reporting.
AIDS in 2005
(See the box, before the References section, for AIDS definition. The following data are from 50 states and the District of Columbia.)
* An estimated 19,248 MSM (17,230 MSM and 2,018 MSM who inject drugs) received a diagnosis of AIDS, accounting for 65% of male adults and adolescents and 47% of all people who received a diagnosis of AIDS [1].
* An estimated 7,293 MSM (5,929 MSM and 1,364 MSM who inject drugs) with AIDS died, accounting for 60% of all men and 45% of all people with AIDS who died [1].
* Since the beginning of the epidemic, an estimated 517,992 MSM (452,111 MSM and 65,881 MSM who inject drugs) had received a diagnosis of AIDS, accounting for 68% of male adults and adolescents who received a diagnosis of AIDS and 54% of all people who received a diagnosis of AIDS [1].
* Since the beginning of the epidemic, an estimated 300,669 MSM (260,749 MSM and 39,920 MSM who inject drugs) with AIDS had died, accounting for 68% of male adults and adolescents with AIDS who had died and 57% of all people with AIDS who had died [1].
* At the end of 2005, an estimated 217,323 MSM (191,362 MSM and 25,961 MSM who inject drugs) were living with AIDS, representing 67% of male adults and adolescents living with AIDS and 52% of all people living with AIDS [1].
HIV/AIDS in 2005
(The following bullets refer to the 33 states with long-term, confidential name-based HIV reporting. See the box, before the References section, for a list of the 33 states.)
* In the 33 states with long-term, confidential name-based HIV reporting, an estimated 19,620 MSM (18,296 MSM and 1,324 MSM who inject drugs) received a diagnosis of HIV/AIDS, accounting for 71% of male adults and adolescents and 53% of all people receiving an HIV/AIDS diagnosis that year [1].
* The number of HIV/AIDS diagnoses among MSM (including MSM who inject drugs) increased 11% from 2001 through 2005 [1]. It is not known whether this increase is due to an increase in the testing of persons with risk factors, which results in more HIV diagnoses, or due to an increase in cases of HIV infection
* An estimated 231,893 MSM (207,810 MSM and 24,083 MSM who inject drugs) were living with HIV/AIDS [1].
Transmission categories of male adults and adolescents with HIV/AIDS diagnosed during 2005
No. = 27,455 Male-to-male sexual contact: 67% High-risk heterosexual contact: 15% Injection drug use: 13% Male-to-male sexual contact and injection drug use: 5% Other: <1%
Note. Based on data from 33 states with long-term, confidential name-based HIV reporting. Because of rounding, percentages may not equal 100.
Race/ethnicity of MSM living with HIV/AIDS, 2005
MSM; No. = 207,810 White: 50% Black: 32% Hispanic: 16% Asian/Pacific Islander: 1% American Indian/Alaska Native: <1%
MSM who inject drugs; No. = 24,083 White: 45% Black: 39% Hispanic: 14% Asian/Pacific Islander: <1% American Indian/Alaska Native: 1%
Note. Based on 33 states with long-term, confidential name-based HIV reporting.
AIDS in 2005
(See the box, before the References section, for AIDS definition. The following data are from 50 states and the District of Columbia.)
* An estimated 19,248 MSM (17,230 MSM and 2,018 MSM who inject drugs) received a diagnosis of AIDS, accounting for 65% of male adults and adolescents and 47% of all people who received a diagnosis of AIDS [1].
* An estimated 7,293 MSM (5,929 MSM and 1,364 MSM who inject drugs) with AIDS died, accounting for 60% of all men and 45% of all people with AIDS who died [1].
* Since the beginning of the epidemic, an estimated 517,992 MSM (452,111 MSM and 65,881 MSM who inject drugs) had received a diagnosis of AIDS, accounting for 68% of male adults and adolescents who received a diagnosis of AIDS and 54% of all people who received a diagnosis of AIDS [1].
* Since the beginning of the epidemic, an estimated 300,669 MSM (260,749 MSM and 39,920 MSM who inject drugs) with AIDS had died, accounting for 68% of male adults and adolescents with AIDS who had died and 57% of all people with AIDS who had died [1].
* At the end of 2005, an estimated 217,323 MSM (191,362 MSM and 25,961 MSM who inject drugs) were living with AIDS, representing 67% of male adults and adolescents living with AIDS and 52% of all people living with AIDS [1].
HIV/AIDS among Men Who Have Sex with Men
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HIV/AIDS among Men Who Have Sex with Men
In the United States, HIV infection and AIDS have had a tremendous effect on men who have sex with men (MSM). MSM accounted for 71% of all HIV infections among male adults and adolescents in 2005 (based on data from 33 states with long-term, confidential name-based HIV reporting), even though only about 5% to 7% of male adults and adolescents in the United States identify themselves as MSM [1, 2].
The number of HIV diagnoses for MSM decreased during the 1980s and 1990s, but recent surveillance data show an increase in HIV diagnoses for this group [3, 4]. Additionally, racial disparities exist with regard to HIV diagnoses within the MSM population. A recent study, conducted in 5 large US cities, found that HIV prevalence among black MSM (46%) was more than twice that among white MSM (21%) [5].
The recent overall increase in HIV diagnoses for MSM, coupled with racial disparities, strongly points to a continued need for appropriate prevention and education services tailored for specific subgroups of MSM, especially those who are members of minority races/ethnicities.
HIV/AIDS among Men Who Have Sex with Men
In the United States, HIV infection and AIDS have had a tremendous effect on men who have sex with men (MSM). MSM accounted for 71% of all HIV infections among male adults and adolescents in 2005 (based on data from 33 states with long-term, confidential name-based HIV reporting), even though only about 5% to 7% of male adults and adolescents in the United States identify themselves as MSM [1, 2].
The number of HIV diagnoses for MSM decreased during the 1980s and 1990s, but recent surveillance data show an increase in HIV diagnoses for this group [3, 4]. Additionally, racial disparities exist with regard to HIV diagnoses within the MSM population. A recent study, conducted in 5 large US cities, found that HIV prevalence among black MSM (46%) was more than twice that among white MSM (21%) [5].
The recent overall increase in HIV diagnoses for MSM, coupled with racial disparities, strongly points to a continued need for appropriate prevention and education services tailored for specific subgroups of MSM, especially those who are members of minority races/ethnicities.
Wednesday, December 12, 2007
Genetic variability
Genetic variability
The phylogenetic tree of the SIV and HIV (click on image for a detailed description).
The phylogenetic tree of the SIV and HIV (click on image for a detailed description).
Map showing HIV-1 subtype prevalence. The bigger the pie chart, the more infections are present.
Map showing HIV-1 subtype prevalence. The bigger the pie chart, the more infections are present.
HIV differs from many other viruses as it has very high genetic variability. This diversity is a result of its fast replication cycle, with the generation of 109 to 1010 virions every day, coupled with a high mutation rate of approximately 3 x 10-5 per nucleotide base per cycle of replication and recombinogenic properties of reverse transcriptase.[55] This complex scenario leads to the generation of many variants of HIV in a single infected patient in the course of one day.[55] This variability is compounded when a single cell is simultaneously infected by two or more different strains of HIV. When simultaneous infection occurs, the genome of progeny virions may be composed of RNA strands from two different strains. This hybrid virion then infects a new cell where it undergoes replication. As this happens, the reverse transcriptase, by jumping back and forth between the two different RNA templates, will generate a newly synthesized retroviral DNA sequence that is a recombinant between the two parental genomes.[55] This recombination is most obvious when it occurs between subtypes.[55]
The closely related simian immunodeficiency virus (SIV) exhibits a somewhat different behavior: in its natural hosts, African green monkeys and sooty mangabeys, the retrovirus is present in high levels in the blood, but evokes only a mild immune response,[56] does not cause the development of simian AIDS,[57] and does not undergo the extensive mutation and recombination typical of HIV.[58] By contrast, infection of heterologous hosts (rhesus or cynomologus macaques) with SIV results in the generation of genetic diversity that is on the same order as HIV in infected humans; these heterologous hosts also develop simian AIDS.[59] The relationship, if any, between genetic diversification, immune response, and disease progression is unknown.
Three groups of HIV-1 have been identified on the basis of differences in env: M, N, and O.[60] Group M is the most prevalent and is subdivided into eight subtypes (or clades), based on the whole genome, which are geographically distinct.[61] The most prevalent are subtypes B (found mainly in North America and Europe), A and D (found mainly in Africa), and C (found mainly in Africa and Asia); these subtypes form branches in the phylogenetic tree representing the lineage of the M group of HIV-1. Coinfection with distinct subtypes gives rise to circulating recombinant forms (CRFs). In 2000, the last year in which an analysis of global subtype prevalence was made, 47.2% of infections worldwide were of subtype C, 26.7% were of subtype A/CRF02_AG, 12.3% were of subtype B, 5.3% were of subtype D, 3.2% were of CRF_AE, and the remaining 5.3% were composed of other subtypes and CRFs.[62] Most HIV-1 research is focused on subtype B; few laboratories focus on the other subtypes.[63]
The genetic sequence of HIV-2 is only partially homologous to HIV-1 and more closely resembles that of SIV than HIV-1.
The phylogenetic tree of the SIV and HIV (click on image for a detailed description).
The phylogenetic tree of the SIV and HIV (click on image for a detailed description).
Map showing HIV-1 subtype prevalence. The bigger the pie chart, the more infections are present.
Map showing HIV-1 subtype prevalence. The bigger the pie chart, the more infections are present.
HIV differs from many other viruses as it has very high genetic variability. This diversity is a result of its fast replication cycle, with the generation of 109 to 1010 virions every day, coupled with a high mutation rate of approximately 3 x 10-5 per nucleotide base per cycle of replication and recombinogenic properties of reverse transcriptase.[55] This complex scenario leads to the generation of many variants of HIV in a single infected patient in the course of one day.[55] This variability is compounded when a single cell is simultaneously infected by two or more different strains of HIV. When simultaneous infection occurs, the genome of progeny virions may be composed of RNA strands from two different strains. This hybrid virion then infects a new cell where it undergoes replication. As this happens, the reverse transcriptase, by jumping back and forth between the two different RNA templates, will generate a newly synthesized retroviral DNA sequence that is a recombinant between the two parental genomes.[55] This recombination is most obvious when it occurs between subtypes.[55]
The closely related simian immunodeficiency virus (SIV) exhibits a somewhat different behavior: in its natural hosts, African green monkeys and sooty mangabeys, the retrovirus is present in high levels in the blood, but evokes only a mild immune response,[56] does not cause the development of simian AIDS,[57] and does not undergo the extensive mutation and recombination typical of HIV.[58] By contrast, infection of heterologous hosts (rhesus or cynomologus macaques) with SIV results in the generation of genetic diversity that is on the same order as HIV in infected humans; these heterologous hosts also develop simian AIDS.[59] The relationship, if any, between genetic diversification, immune response, and disease progression is unknown.
Three groups of HIV-1 have been identified on the basis of differences in env: M, N, and O.[60] Group M is the most prevalent and is subdivided into eight subtypes (or clades), based on the whole genome, which are geographically distinct.[61] The most prevalent are subtypes B (found mainly in North America and Europe), A and D (found mainly in Africa), and C (found mainly in Africa and Asia); these subtypes form branches in the phylogenetic tree representing the lineage of the M group of HIV-1. Coinfection with distinct subtypes gives rise to circulating recombinant forms (CRFs). In 2000, the last year in which an analysis of global subtype prevalence was made, 47.2% of infections worldwide were of subtype C, 26.7% were of subtype A/CRF02_AG, 12.3% were of subtype B, 5.3% were of subtype D, 3.2% were of CRF_AE, and the remaining 5.3% were composed of other subtypes and CRFs.[62] Most HIV-1 research is focused on subtype B; few laboratories focus on the other subtypes.[63]
The genetic sequence of HIV-2 is only partially homologous to HIV-1 and more closely resembles that of SIV than HIV-1.
Replication cycle
Replication cycle
Schematic representation of the key structural features of HIV-1 entry into T cells. The two bottom images show alternate models for entry into cells.
Schematic representation of the key structural features of HIV-1 entry into T cells. The two bottom images show alternate models for entry into cells.
The HIV replication cycle
The HIV replication cycle
Entry to the cell
HIV enters macrophages and CD4+ T cells by the adsorption of glycoproteins on its surface to receptors on the target cell followed by fusion of the viral envelope with the cell membrane and the release of the HIV capsid into the cell.[48][49]
Entry to the cell begins through interaction of the trimeric envelope complex (gp160 spike, discussed above) and both CD4 and a chemokine receptor (generally either CCR5 or CXCR4, but others are known to interact) on the cell surface.[48][49] The gp160 spike contains binding domains for both CD4 and chemokine receptors.[48][49] The first step in fusion involves the high-affinity attachment of the CD4 binding domains of gp120 to CD4. Once gp120 is bound with the CD4 protein, the envelope complex undergoes a structural change, exposing the chemokine binding domains of gp120 and allowing them to interact with the target chemokine receptor.[48][49] This allows for a more stable two-pronged attachment, which allows the N-terminal fusion peptide gp41 to penetrate the cell membrane.[48][49] Repeat sequences in gp41, HR1 and HR2 then interact, causing the collapse of the extracellular portion of gp41 into a hairpin. This loop structure brings the virus and cell membranes close together, allowing fusion of the membranes and subsequent entry of the viral capsid.[48][49]
Once HIV has bound to the target cell, the HIV RNA and various enzymes, including reverse transcriptase, integrase, ribonuclease and protease, are injected into the cell.[48]
HIV can infect dendritic cells (DCs) by this CD4-CCR5 route, but another route using mannose-specific C-type lectin receptors such as DC-SIGN can also be used.[50] DCs are one of the first cells encountered by the virus during sexual transmission. They are currently thought to play an important role by transmitting HIV to T cells once the virus has been captured in the mucosa by DCs.[50]
Replication and transcription
Once the viral capsid enters the cell, an enzyme called reverse transcriptase liberates the single-stranded (+)RNA from the attached viral proteins and copies it into a complementary DNA.[51] This process of reverse transcription is extremely error-prone and it is during this step that mutations may occur. Such mutations may cause drug resistance. The reverse transcriptase then makes a complementary DNA strand to form a double-stranded viral DNA intermediate (vDNA). This vDNA is then transported into the cell nucleus. The integration of the viral DNA into the host cell's genome is carried out by another viral enzyme called integrase.[51]
This integrated viral DNA may then lie dormant, in the latent stage of HIV infection.[51] To actively produce the virus, certain cellular transcription factors need to be present, the most important of which is NF-κB (NF kappa B), which is upregulated when T cells become activated.[52] This means that those cells most likely to be killed by HIV are in fact those currently fighting infection.
Rev-mediated HIV mRNA transport. Rev (red) binds the Rev response element (RRE, blue) to mediate export of unspliced and singly spliced mRNA from the nucleus to the cytoplasm.
Rev-mediated HIV mRNA transport. Rev (red) binds the Rev response element (RRE, blue) to mediate export of unspliced and singly spliced mRNA from the nucleus to the cytoplasm.
In this replication process, the integrated provirus is copied to mRNA which is then spliced into smaller pieces. These small pieces produce the regulatory proteins Tat (which encourages new virus production) and Rev. As Rev accumulates it gradually starts to inhibit mRNA splicing.[53] At this stage, the structural proteins Gag and Env are produced from the full-length mRNA. The full-length RNA is actually the virus genome; it binds to the Gag protein and is packaged into new virus particles.
HIV-1 and HIV-2 appear to package their RNA differently; HIV-1 will bind to any appropriate RNA whereas HIV-2 will preferentially bind to the mRNA which was used to create the Gag protein itself. This may mean that HIV-1 is better able to mutate (HIV-1 infection progresses to AIDS faster than HIV-2 infection and is responsible for the majority of global infections).
Assembly and release
The final step of the viral cycle, assembly of new HIV-1 virons, begins at the plasma membrane of the host cell. The Env polyprotein (gp160) goes through the endoplasmic reticulum and is transported to the Golgi complex where it is cleaved by protease and processed into the two HIV envelope glycoproteins gp41 and gp120. These are transported to the plasma membrane of the host cell where gp41 anchors the gp120 to the membrane of the infected cell. The Gag (p55) and Gag-Pol (p160) polyproteins also associate with the inner surface of the plasma membrane along with the HIV genomic RNA as the forming virion begins to bud from the host cell. Maturation either occurs in the forming bud or in the immature virion after it buds from the host cell. During maturation, HIV proteases cleave the polyproteins into individual functional HIV proteins and enzymes. The various structural components then assemble to produce a mature HIV virion.[54] This cleavage step can be inhibited by protease inhibitors. The mature virus is then able to infect another cell.
Schematic representation of the key structural features of HIV-1 entry into T cells. The two bottom images show alternate models for entry into cells.
Schematic representation of the key structural features of HIV-1 entry into T cells. The two bottom images show alternate models for entry into cells.
The HIV replication cycle
The HIV replication cycle
Entry to the cell
HIV enters macrophages and CD4+ T cells by the adsorption of glycoproteins on its surface to receptors on the target cell followed by fusion of the viral envelope with the cell membrane and the release of the HIV capsid into the cell.[48][49]
Entry to the cell begins through interaction of the trimeric envelope complex (gp160 spike, discussed above) and both CD4 and a chemokine receptor (generally either CCR5 or CXCR4, but others are known to interact) on the cell surface.[48][49] The gp160 spike contains binding domains for both CD4 and chemokine receptors.[48][49] The first step in fusion involves the high-affinity attachment of the CD4 binding domains of gp120 to CD4. Once gp120 is bound with the CD4 protein, the envelope complex undergoes a structural change, exposing the chemokine binding domains of gp120 and allowing them to interact with the target chemokine receptor.[48][49] This allows for a more stable two-pronged attachment, which allows the N-terminal fusion peptide gp41 to penetrate the cell membrane.[48][49] Repeat sequences in gp41, HR1 and HR2 then interact, causing the collapse of the extracellular portion of gp41 into a hairpin. This loop structure brings the virus and cell membranes close together, allowing fusion of the membranes and subsequent entry of the viral capsid.[48][49]
Once HIV has bound to the target cell, the HIV RNA and various enzymes, including reverse transcriptase, integrase, ribonuclease and protease, are injected into the cell.[48]
HIV can infect dendritic cells (DCs) by this CD4-CCR5 route, but another route using mannose-specific C-type lectin receptors such as DC-SIGN can also be used.[50] DCs are one of the first cells encountered by the virus during sexual transmission. They are currently thought to play an important role by transmitting HIV to T cells once the virus has been captured in the mucosa by DCs.[50]
Replication and transcription
Once the viral capsid enters the cell, an enzyme called reverse transcriptase liberates the single-stranded (+)RNA from the attached viral proteins and copies it into a complementary DNA.[51] This process of reverse transcription is extremely error-prone and it is during this step that mutations may occur. Such mutations may cause drug resistance. The reverse transcriptase then makes a complementary DNA strand to form a double-stranded viral DNA intermediate (vDNA). This vDNA is then transported into the cell nucleus. The integration of the viral DNA into the host cell's genome is carried out by another viral enzyme called integrase.[51]
This integrated viral DNA may then lie dormant, in the latent stage of HIV infection.[51] To actively produce the virus, certain cellular transcription factors need to be present, the most important of which is NF-κB (NF kappa B), which is upregulated when T cells become activated.[52] This means that those cells most likely to be killed by HIV are in fact those currently fighting infection.
Rev-mediated HIV mRNA transport. Rev (red) binds the Rev response element (RRE, blue) to mediate export of unspliced and singly spliced mRNA from the nucleus to the cytoplasm.
Rev-mediated HIV mRNA transport. Rev (red) binds the Rev response element (RRE, blue) to mediate export of unspliced and singly spliced mRNA from the nucleus to the cytoplasm.
In this replication process, the integrated provirus is copied to mRNA which is then spliced into smaller pieces. These small pieces produce the regulatory proteins Tat (which encourages new virus production) and Rev. As Rev accumulates it gradually starts to inhibit mRNA splicing.[53] At this stage, the structural proteins Gag and Env are produced from the full-length mRNA. The full-length RNA is actually the virus genome; it binds to the Gag protein and is packaged into new virus particles.
HIV-1 and HIV-2 appear to package their RNA differently; HIV-1 will bind to any appropriate RNA whereas HIV-2 will preferentially bind to the mRNA which was used to create the Gag protein itself. This may mean that HIV-1 is better able to mutate (HIV-1 infection progresses to AIDS faster than HIV-2 infection and is responsible for the majority of global infections).
Assembly and release
The final step of the viral cycle, assembly of new HIV-1 virons, begins at the plasma membrane of the host cell. The Env polyprotein (gp160) goes through the endoplasmic reticulum and is transported to the Golgi complex where it is cleaved by protease and processed into the two HIV envelope glycoproteins gp41 and gp120. These are transported to the plasma membrane of the host cell where gp41 anchors the gp120 to the membrane of the infected cell. The Gag (p55) and Gag-Pol (p160) polyproteins also associate with the inner surface of the plasma membrane along with the HIV genomic RNA as the forming virion begins to bud from the host cell. Maturation either occurs in the forming bud or in the immature virion after it buds from the host cell. During maturation, HIV proteases cleave the polyproteins into individual functional HIV proteins and enzymes. The various structural components then assemble to produce a mature HIV virion.[54] This cleavage step can be inhibited by protease inhibitors. The mature virus is then able to infect another cell.
Tropism
Tropism
The term viral tropism refers to which cell types HIV infects. HIV can infect a variety of immune cells such as CD4+ T cells, macrophages, and microglial cells. HIV-1 entry to macrophages and CD4+ T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells and also with chemokine coreceptors.[32]
Macrophage (M-tropic) strains of HIV-1, or non-syncitia-inducing strains (NSI) use the β-chemokine receptor CCR5 for entry and are thus able to replicate in macrophages and CD4+ T cells.[34] This CCR5 coreceptor is used by almost all primary HIV-1 isolates regardless of viral genetic subtype. Indeed, macrophages play a key role in several critical aspects of HIV infection. They appear to be the first cells infected by HIV and perhaps the source of HIV production when CD4+ cells become depleted in the patient. Macrophages and microglial cells are the cells infected by HIV in the central nervous system. In tonsils and adenoids of HIV-infected patients, macrophages fuse into multinucleated giant cells that produce huge amounts of virus.
T-tropic isolates, or syncitia-inducing (SI) strains replicate in primary CD4+ T cells as well as in macrophages and use the α-chemokine receptor, CXCR4, for entry.[34][35][36] Dual-tropic HIV-1 strains are thought to be transitional strains of the HIV-1 virus and thus are able to use both CCR5 and CXCR4 as co-receptors for viral entry.
The α-chemokine, SDF-1, a ligand for CXCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by down-regulating the expression of CXCR4 on the surface of these cells. HIV that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4, and those that use both, X4R5. However, the use of coreceptor alone does not explain viral tropism, as not all R5 viruses are able to use CCR5 on macrophages for a productive infection[34] and HIV can also infect a subtype of myeloid dendritic cells,[37] which probably constitute a reservoir that maintains infection when CD4+ T cell numbers have declined to extremely low levels.
Some people are resistant to certain strains of HIV.[38] One example of how this occurs is people with the CCR5-Δ32 mutation; these people are resistant to infection with R5 virus as the mutation stops HIV from binding to this coreceptor, reducing its ability to infect target cells.
Sexual intercourse is the major mode of HIV transmission. Both X4 and R5 HIV are present in the seminal fluid which is passed from partner to partner. The virions can then infect numerous cellular targets and disseminate into the whole organism. However, a selection process leads to a predominant transmission of the R5 virus through this pathway.[39][40][41] How this selective process works is still under investigation, but one model is that spermatozoa may selectively carry R5 HIV as they possess both CCR3 and CCR5 but not CXCR4 on their surface[42] and that genital epithelial cells preferentially sequester X4 virus.[43] In patients infected with subtype B HIV-1, there is often a co-receptor switch in late-stage disease and T-tropic variants appear that can infect a variety of T cells through CXCR4.[44] These variants then replicate more aggressively with heightened virulence that causes rapid T cell depletion, immune system collapse, and opportunistic infections that mark the advent of AIDS.[45] Thus, during the course of infection, viral adaptation to the use of CXCR4 instead of CCR5 may be a key step in the progression to AIDS. A number of studies with subtype B-infected individuals have determined that between 40 and 50% of AIDS patients can harbour viruses of the SI, and presumably the X4, phenotype.[46][47]
The term viral tropism refers to which cell types HIV infects. HIV can infect a variety of immune cells such as CD4+ T cells, macrophages, and microglial cells. HIV-1 entry to macrophages and CD4+ T cells is mediated through interaction of the virion envelope glycoproteins (gp120) with the CD4 molecule on the target cells and also with chemokine coreceptors.[32]
Macrophage (M-tropic) strains of HIV-1, or non-syncitia-inducing strains (NSI) use the β-chemokine receptor CCR5 for entry and are thus able to replicate in macrophages and CD4+ T cells.[34] This CCR5 coreceptor is used by almost all primary HIV-1 isolates regardless of viral genetic subtype. Indeed, macrophages play a key role in several critical aspects of HIV infection. They appear to be the first cells infected by HIV and perhaps the source of HIV production when CD4+ cells become depleted in the patient. Macrophages and microglial cells are the cells infected by HIV in the central nervous system. In tonsils and adenoids of HIV-infected patients, macrophages fuse into multinucleated giant cells that produce huge amounts of virus.
T-tropic isolates, or syncitia-inducing (SI) strains replicate in primary CD4+ T cells as well as in macrophages and use the α-chemokine receptor, CXCR4, for entry.[34][35][36] Dual-tropic HIV-1 strains are thought to be transitional strains of the HIV-1 virus and thus are able to use both CCR5 and CXCR4 as co-receptors for viral entry.
The α-chemokine, SDF-1, a ligand for CXCR4, suppresses replication of T-tropic HIV-1 isolates. It does this by down-regulating the expression of CXCR4 on the surface of these cells. HIV that use only the CCR5 receptor are termed R5, those that only use CXCR4 are termed X4, and those that use both, X4R5. However, the use of coreceptor alone does not explain viral tropism, as not all R5 viruses are able to use CCR5 on macrophages for a productive infection[34] and HIV can also infect a subtype of myeloid dendritic cells,[37] which probably constitute a reservoir that maintains infection when CD4+ T cell numbers have declined to extremely low levels.
Some people are resistant to certain strains of HIV.[38] One example of how this occurs is people with the CCR5-Δ32 mutation; these people are resistant to infection with R5 virus as the mutation stops HIV from binding to this coreceptor, reducing its ability to infect target cells.
Sexual intercourse is the major mode of HIV transmission. Both X4 and R5 HIV are present in the seminal fluid which is passed from partner to partner. The virions can then infect numerous cellular targets and disseminate into the whole organism. However, a selection process leads to a predominant transmission of the R5 virus through this pathway.[39][40][41] How this selective process works is still under investigation, but one model is that spermatozoa may selectively carry R5 HIV as they possess both CCR3 and CCR5 but not CXCR4 on their surface[42] and that genital epithelial cells preferentially sequester X4 virus.[43] In patients infected with subtype B HIV-1, there is often a co-receptor switch in late-stage disease and T-tropic variants appear that can infect a variety of T cells through CXCR4.[44] These variants then replicate more aggressively with heightened virulence that causes rapid T cell depletion, immune system collapse, and opportunistic infections that mark the advent of AIDS.[45] Thus, during the course of infection, viral adaptation to the use of CXCR4 instead of CCR5 may be a key step in the progression to AIDS. A number of studies with subtype B-infected individuals have determined that between 40 and 50% of AIDS patients can harbour viruses of the SI, and presumably the X4, phenotype.[46][47]
Classification
Classification
HIV was classified as a member of the genus Lentivirus,[8] part of the family of Retroviridae.[9] Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period.[10] Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase so that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.
Two species of HIV infect humans: HIV-1 and HIV-2.
HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees (Pan troglodytes troglodytes) to humans during the twentieth century.[11][12] HIV-1 is the virus that was initially discovered and termed LAV. It is more virulent and relatively easy transmitted and is the cause of the majority of HIV infections globally.
HIV-2 may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon.[13] HIV-2 is less transmittable than HIV-1 and is largely confined to West Africa.[13]
Early history
See AIDS origin#History of known cases and spread for early cases of HIV / AIDS.
Transmission
For more details on this topic, see AIDS transmission and prevention
Estimated per act risk for acquisition
of HIV-1 by exposure route[14]
Exposure Route Estimated infections
per 10,000 exposures
to an infected source
Blood Transfusion 9,000[15]
Childbirth 2,500[16]
Needle-sharing injection drug use 67[17]
Receptive anal intercourse* 50[18][19]
Percutaneous needle stick 30[20]
Receptive penile-vaginal intercourse* 10[18][19][21]
Insertive anal intercourse* 6.5[18][19]
Insertive penile-vaginal intercourse* 5[18][19]
Receptive fellatio* 1[19]
Insertive fellatio* 0.5[19]
* assuming no condom use
Since the beginning of the pandemic, three main transmission routes for HIV have been identified:
* Sexual route. The majority of HIV infections are acquired through unprotected sexual relations. Sexual transmission can occur when infected sexual secretions of one partner come into contact with the genital, oral, or rectal mucous membranes of another.
* Blood or blood product route. This transmission route can account for infections in intravenous drug users, hemophiliacs and recipients of blood transfusions (though most transfusions are checked for HIV in the developed world) and blood products. It is also of concern for persons receiving medical care in regions where there is prevalent substandard hygiene in the use of injection equipment, such as the reuse of needles in Third World countries. HIV can also be spread through the sharing of needles. Health care workers such as nurses, laboratory workers, and doctors, have also been infected, although this occurs more rarely. People who give and receive tattoos, piercings, and scarification procedures can also be at risk of infection.
* Mother-to-child transmission (MTCT). The transmission of the virus from the mother to the child can occur in utero during the last weeks of pregnancy and at childbirth. In the absence of treatment, the transmission rate between the mother and child is 25%.[16] However, where drug treatment and Cesarian section are available, this can be reduced to 1%.[16] Breast feeding also presents a risk of infection for the baby.
HIV-2 is transmitted much less frequently by the MTCT and sexual route than HIV-1.
HIV has been found at low concentrations in the saliva, tears and urine of infected individuals, but there are no recorded cases of infection by these secretions and the potential risk of transmission is negligible.[22] The use of physical barriers such as the latex condom is widely advocated to reduce the sexual transmission of HIV. Spermicide, when used alone or with vaginal contraceptives like a diaphragm, actually increases the male to female transmission rate due to inflammation of the vagina; it should not be considered a barrier to infection.[23] Trials, in which uncircumcised men were randomly assigned to be medically circumcised in sterile conditions and given counseling and other men were not circumcised, have been conducted in South Africa,[24] Kenya[25] and Uganda[26] showing reductions in HIV transmission for heterosexual sex of 60%, 53%, and 48% respectively. As a result, a panel of experts convened by WHO and the UNAIDS Secretariat has "recommended that male circumcision now be recognized as an additional important intervention to reduce the risk of heterosexually acquired HIV infection in men [in South Africa, Kenya and Uganda] ."[27] Research is clarifying whether there is a historical relationship between rates of male circumcision and rates of HIV in differing social and cultural contexts. Critics point out that any correlation between circumcision and HIV is likely to come from cultural factors (which govern not only whether someone is circumcised, but also their sexual practices and beliefs).[28] South African medical experts are concerned that the repeated use of unsterilized blades in the ritual (not medical) circumcision of adolescent boys may be spreading HIV.[29]
Structure and genome
Main article: HIV structure and genome
Diagram of HIV
Diagram of HIV
HIV is different in structure from other retroviruses. It is about 120 nm in diameter (120 billionths of a meter; around 60 times smaller than a red blood cell) and roughly spherical.[30]
EM of HIV
EM of HIV
It is composed of two copies of positive single-stranded RNA that codes for the virus's nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24.[31] The single-stranded RNA is tightly bound to nucleocapsid proteins, p7 and enzymes needed for the development of the virion such as reverse transcriptase, proteases, ribonuclease and integrase. A matrix composed of the viral protein p17 surrounds the capsid ensuring the integrity of the virion particle.[31] This is, in turn, surrounded by the viral envelope which is composed of two layers of fatty molecules called phospholipids taken from the membrane of a human cell when a newly formed virus particle buds from the cell. Embedded in the viral envelope are proteins from the host cell and about 70 copies of a complex HIV protein that protrudes through the surface of the virus particle.[31] This protein, known as Env, consists of a cap made of three molecules called glycoprotein (gp) 120, and a stem consisting of three gp41 molecules that anchor the structure into the viral envelope.[32] This glycoprotein complex enables the virus to attach to and fuse with target cells to initiate the infectious cycle.[32] Both these surface proteins, especially gp120, have been considered as targets of future treatments or vaccines against HIV.[33]
Of the nine genes that are encoded within the RNA genome, three of these genes, gag, pol, and env, contain information needed to make the structural proteins for new virus particles.[31] env, for example, codes for a protein called gp160 that is broken down by a viral enzyme to form gp120 and gp41. The six remaining genes, tat, rev, nef, vif, vpr, and vpu (or vpx in the case of HIV-2), are regulatory genes for proteins that control the ability of HIV to infect cells, produce new copies of virus (replicate), or cause disease.[31] The protein encoded by nef, for instance, appears necessary for the virus to replicate efficiently, and the vpu-encoded protein influences the release of new virus particles from infected cells.[31] The ends of each strand of HIV RNA contain an RNA sequence called the long terminal repeat (LTR). Regions in the LTR act as switches to control production of new viruses and can be triggered by proteins from either HIV or the host cell.[31]
HIV was classified as a member of the genus Lentivirus,[8] part of the family of Retroviridae.[9] Lentiviruses have many common morphologies and biological properties. Many species are infected by lentiviruses, which are characteristically responsible for long-duration illnesses with a long incubation period.[10] Lentiviruses are transmitted as single-stranded, positive-sense, enveloped RNA viruses. Upon entry of the target cell, the viral RNA genome is converted to double-stranded DNA by a virally encoded reverse transcriptase that is present in the virus particle. This viral DNA is then integrated into the cellular DNA by a virally encoded integrase so that the genome can be transcribed. Once the virus has infected the cell, two pathways are possible: either the virus becomes latent and the infected cell continues to function, or the virus becomes active and replicates, and a large number of virus particles are liberated that can then infect other cells.
Two species of HIV infect humans: HIV-1 and HIV-2.
HIV-1 is thought to have originated in southern Cameroon after jumping from wild chimpanzees (Pan troglodytes troglodytes) to humans during the twentieth century.[11][12] HIV-1 is the virus that was initially discovered and termed LAV. It is more virulent and relatively easy transmitted and is the cause of the majority of HIV infections globally.
HIV-2 may have originated from the Sooty Mangabey (Cercocebus atys), an Old World monkey of Guinea-Bissau, Gabon, and Cameroon.[13] HIV-2 is less transmittable than HIV-1 and is largely confined to West Africa.[13]
Early history
See AIDS origin#History of known cases and spread for early cases of HIV / AIDS.
Transmission
For more details on this topic, see AIDS transmission and prevention
Estimated per act risk for acquisition
of HIV-1 by exposure route[14]
Exposure Route Estimated infections
per 10,000 exposures
to an infected source
Blood Transfusion 9,000[15]
Childbirth 2,500[16]
Needle-sharing injection drug use 67[17]
Receptive anal intercourse* 50[18][19]
Percutaneous needle stick 30[20]
Receptive penile-vaginal intercourse* 10[18][19][21]
Insertive anal intercourse* 6.5[18][19]
Insertive penile-vaginal intercourse* 5[18][19]
Receptive fellatio* 1[19]
Insertive fellatio* 0.5[19]
* assuming no condom use
Since the beginning of the pandemic, three main transmission routes for HIV have been identified:
* Sexual route. The majority of HIV infections are acquired through unprotected sexual relations. Sexual transmission can occur when infected sexual secretions of one partner come into contact with the genital, oral, or rectal mucous membranes of another.
* Blood or blood product route. This transmission route can account for infections in intravenous drug users, hemophiliacs and recipients of blood transfusions (though most transfusions are checked for HIV in the developed world) and blood products. It is also of concern for persons receiving medical care in regions where there is prevalent substandard hygiene in the use of injection equipment, such as the reuse of needles in Third World countries. HIV can also be spread through the sharing of needles. Health care workers such as nurses, laboratory workers, and doctors, have also been infected, although this occurs more rarely. People who give and receive tattoos, piercings, and scarification procedures can also be at risk of infection.
* Mother-to-child transmission (MTCT). The transmission of the virus from the mother to the child can occur in utero during the last weeks of pregnancy and at childbirth. In the absence of treatment, the transmission rate between the mother and child is 25%.[16] However, where drug treatment and Cesarian section are available, this can be reduced to 1%.[16] Breast feeding also presents a risk of infection for the baby.
HIV-2 is transmitted much less frequently by the MTCT and sexual route than HIV-1.
HIV has been found at low concentrations in the saliva, tears and urine of infected individuals, but there are no recorded cases of infection by these secretions and the potential risk of transmission is negligible.[22] The use of physical barriers such as the latex condom is widely advocated to reduce the sexual transmission of HIV. Spermicide, when used alone or with vaginal contraceptives like a diaphragm, actually increases the male to female transmission rate due to inflammation of the vagina; it should not be considered a barrier to infection.[23] Trials, in which uncircumcised men were randomly assigned to be medically circumcised in sterile conditions and given counseling and other men were not circumcised, have been conducted in South Africa,[24] Kenya[25] and Uganda[26] showing reductions in HIV transmission for heterosexual sex of 60%, 53%, and 48% respectively. As a result, a panel of experts convened by WHO and the UNAIDS Secretariat has "recommended that male circumcision now be recognized as an additional important intervention to reduce the risk of heterosexually acquired HIV infection in men [in South Africa, Kenya and Uganda] ."[27] Research is clarifying whether there is a historical relationship between rates of male circumcision and rates of HIV in differing social and cultural contexts. Critics point out that any correlation between circumcision and HIV is likely to come from cultural factors (which govern not only whether someone is circumcised, but also their sexual practices and beliefs).[28] South African medical experts are concerned that the repeated use of unsterilized blades in the ritual (not medical) circumcision of adolescent boys may be spreading HIV.[29]
Structure and genome
Main article: HIV structure and genome
Diagram of HIV
Diagram of HIV
HIV is different in structure from other retroviruses. It is about 120 nm in diameter (120 billionths of a meter; around 60 times smaller than a red blood cell) and roughly spherical.[30]
EM of HIV
EM of HIV
It is composed of two copies of positive single-stranded RNA that codes for the virus's nine genes enclosed by a conical capsid composed of 2,000 copies of the viral protein p24.[31] The single-stranded RNA is tightly bound to nucleocapsid proteins, p7 and enzymes needed for the development of the virion such as reverse transcriptase, proteases, ribonuclease and integrase. A matrix composed of the viral protein p17 surrounds the capsid ensuring the integrity of the virion particle.[31] This is, in turn, surrounded by the viral envelope which is composed of two layers of fatty molecules called phospholipids taken from the membrane of a human cell when a newly formed virus particle buds from the cell. Embedded in the viral envelope are proteins from the host cell and about 70 copies of a complex HIV protein that protrudes through the surface of the virus particle.[31] This protein, known as Env, consists of a cap made of three molecules called glycoprotein (gp) 120, and a stem consisting of three gp41 molecules that anchor the structure into the viral envelope.[32] This glycoprotein complex enables the virus to attach to and fuse with target cells to initiate the infectious cycle.[32] Both these surface proteins, especially gp120, have been considered as targets of future treatments or vaccines against HIV.[33]
Of the nine genes that are encoded within the RNA genome, three of these genes, gag, pol, and env, contain information needed to make the structural proteins for new virus particles.[31] env, for example, codes for a protein called gp160 that is broken down by a viral enzyme to form gp120 and gp41. The six remaining genes, tat, rev, nef, vif, vpr, and vpu (or vpx in the case of HIV-2), are regulatory genes for proteins that control the ability of HIV to infect cells, produce new copies of virus (replicate), or cause disease.[31] The protein encoded by nef, for instance, appears necessary for the virus to replicate efficiently, and the vpu-encoded protein influences the release of new virus particles from infected cells.[31] The ends of each strand of HIV RNA contain an RNA sequence called the long terminal repeat (LTR). Regions in the LTR act as switches to control production of new viruses and can be triggered by proteins from either HIV or the host cell.[31]
From Wikipedia, the free encyclopedia
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Human immunodeficiency virus
Stylized rendering of a cross section of the human immunodeficiency virus
Stylized rendering of a cross section
of the human immunodeficiency virus
Virus classification
Group: Group VI (ssRNA-RT)
Family: Retroviridae
Genus: Lentivirus
Species
* Human immunodeficiency virus 1
* Human immunodeficiency virus 2
International Statistical Classification of Diseases and Related Health Problems Codes
Classification & external resources ICD-10 B20-B24
ICD-9 042-044
Human immunodeficiency virus (HIV) is a retrovirus that can lead to acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Previous names for the virus include human T-lymphotropic virus-III (HTLV-III), lymphadenopathy-associated virus (LAV), or AIDS-associated retrovirus (ARV).[1][2]
Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unprotected sexual intercourse, contaminated needles, and transmission from an infected mother to her baby at birth, or through breast milk. Screening of blood products for HIV in the developed world has largely eliminated transmission through blood transfusions or infected blood products in these countries.
HIV infection in humans is now pandemic. As of January 2006, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1, 1981, making it one of the most destructive pandemics in recorded history. In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. It is estimated that about 0.6% of the world's living population is infected with HIV.[3] A third of these deaths are occurring in sub-Saharan Africa, retarding economic growth and increasing poverty.[4] According to current estimates, HIV is set to infect 90 million people in Africa, resulting in a minimum estimate of 18 million orphans.[5] Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.[6]
HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections. If untreated, eventually most HIV-infected individuals develop AIDS (Acquired Immunodeficiency Syndrome) and die; however about one in ten remains healthy for many years, with no noticeable symptoms.[7] Treatment with anti-retrovirals, where available, increases the life expectancy of people infected with HIV. It is hoped that current and future treatments may allow HIV-infected individuals to achieve a life expectancy approaching that of the general public (see Treatment).
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Human immunodeficiency virus
Stylized rendering of a cross section of the human immunodeficiency virus
Stylized rendering of a cross section
of the human immunodeficiency virus
Virus classification
Group: Group VI (ssRNA-RT)
Family: Retroviridae
Genus: Lentivirus
Species
* Human immunodeficiency virus 1
* Human immunodeficiency virus 2
International Statistical Classification of Diseases and Related Health Problems Codes
Classification & external resources ICD-10 B20-B24
ICD-9 042-044
Human immunodeficiency virus (HIV) is a retrovirus that can lead to acquired immunodeficiency syndrome (AIDS), a condition in humans in which the immune system begins to fail, leading to life-threatening opportunistic infections. Previous names for the virus include human T-lymphotropic virus-III (HTLV-III), lymphadenopathy-associated virus (LAV), or AIDS-associated retrovirus (ARV).[1][2]
Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. The four major routes of transmission are unprotected sexual intercourse, contaminated needles, and transmission from an infected mother to her baby at birth, or through breast milk. Screening of blood products for HIV in the developed world has largely eliminated transmission through blood transfusions or infected blood products in these countries.
HIV infection in humans is now pandemic. As of January 2006, the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO) estimate that AIDS has killed more than 25 million people since it was first recognized on December 1, 1981, making it one of the most destructive pandemics in recorded history. In 2005 alone, AIDS claimed an estimated 2.4–3.3 million lives, of which more than 570,000 were children. It is estimated that about 0.6% of the world's living population is infected with HIV.[3] A third of these deaths are occurring in sub-Saharan Africa, retarding economic growth and increasing poverty.[4] According to current estimates, HIV is set to infect 90 million people in Africa, resulting in a minimum estimate of 18 million orphans.[5] Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but routine access to antiretroviral medication is not available in all countries.[6]
HIV primarily infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages and dendritic cells. HIV infection leads to low levels of CD4+ T cells through three main mechanisms: firstly, direct viral killing of infected cells; secondly, increased rates of apoptosis in infected cells; and thirdly, killing of infected CD4+ T cells by CD8 cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections. If untreated, eventually most HIV-infected individuals develop AIDS (Acquired Immunodeficiency Syndrome) and die; however about one in ten remains healthy for many years, with no noticeable symptoms.[7] Treatment with anti-retrovirals, where available, increases the life expectancy of people infected with HIV. It is hoped that current and future treatments may allow HIV-infected individuals to achieve a life expectancy approaching that of the general public (see Treatment).
Wednesday, November 21, 2007
Kaiser Daily HIV/AIDS Report
Kaiser Daily HIV/AIDS Report
Global Challenges | IANS/Hindustan Times Examines GTZ's Efforts To Educate Congolese Villagers About HIV/AIDS
[Nov 20, 2007]
The IANS/Hindustan Times on Saturday examined the German aid agency GTZ's efforts to educate people living in rural areas of the Democratic Republic of the Congo about HIV/AIDS. GTZ in March launched a mobile sex education caravan to travel hundreds of miles to Maniema, a remote Congolese province with no borders to any other countries and few paved roads. According to the IANS/Times, Maniema has not been highly affected by HIV/AIDS, but the emerging mine industry and influx of workers could create a "new breeding ground" for the disease.
The GTZ project established five stations with different educational components under a mango tree in a village using tree branches and colorful fabric. Setting up under a mango tree aims to appeal to the village's local traditions and make people feel more comfortable about learning the material, the IANS/Times reports. "To bring people together, we found out what is the traditional way to do so. And that's around the mango tree," Achim Koch, project manager of GTZ's youth initiatives in the region, said.
About 10 people visit each station at one time to learn about HIV transmission, prevention and management, as well as different contraceptive methods. The lessons are targeted at youth, particularly young men who were drafted into militia groups during conflict. The learning is interactive and includes games in which participants must describe the risks of HIV in particular situations.
According to the IANS/Times, about 200 people visit the stations daily, and the group has reached more than 16,000 people since it began the project. The United Nations estimates that the country's HIV prevalence is between 1.7% and 7.6% among the general population and that it might be as high as 20% among women in the country's conflict zones (IANS/Hindustan Times, 11/17).
Global Health Literature Digest
These journal articles are selected from a bi-weekly digest produced by the UCSF Institute for Global Health (IGH). The IGH Literature Digest highlights recently published studies of interventions that have one or more of the following aims: to reduce sexual or drug-related risk behaviors, decrease primary or secondary transmission, improve health service delivery and quality of life, or improve HIV treatment and adherence. Studies were either conducted in, or have applications to, resource-limited settings. Summaries and reviewer commentary are the work of IGH authors and have been published here with the permission of IGH.
October 1, 2007
Clinical impact and cost-effectiveness of antiretroviral therapy in India: starting criteria and second-line therapy
Infant feeding in the time of HIV: Assessment of infant feeding policy and programs in four African countries scaling up prevention of mother to child transmission programs
Estimating the number of vertically HIV-infected children eligible for antiretroviral treatment in resource-limited settings
Nursing care of AIDS patients in Uganda
September 10, 2007
Incident and prevalent herpes simplex virus type 2 infection increases risk of HIV acquisition among women in Uganda and Zimbabwe
Cost-effectiveness of on-site antenatal screening to prevent congenital syphilis in rural eastern Cape Province, Republic of South Africa
Continued very high prevalence of HIV infection in rural KwaZulu-Natal, South Africa: a population-based longitudinal study
Maternal HIV infection and placental malaria reduce transplacental antibody transfer and tetanus antibody levels in newborns in Kenya
August 14, 2007
Prevalence of HIV infection in conflict-affected and displaced people in seven sub-Saharan African countries: a systematic review
Flash-Heat Inactivation of HIV-1 in Human Milk: A Potential Method to Reduce Postnatal Transmission in Developing Countries
Antiretroviral durability and tolerability in HIV-infected adults living in urban Kenya
How far will we need to go to reach HIV-infected people in rural South Africa?
July 13, 2007
The cost effectiveness of antiretroviral treatment strategies in resource-limited settings
The protective effect of circumcision on HIV incidence in rural low-risk men circumcised predominantly by traditional circumcisers in Kenya: two-year follow-up of the Kericho HIV cohort study
Risk factors for treatment denial and loss to follow-up in an antiretroviral treatment cohort in Kenya
The impact of HIV treatment on risk behaviour in developing countries: A systematic review
July 2, 2007
HIV, malaria, and infant anemia as risk factors for postneonatal infant mortality among HIV-seropositive women in Kisumu, Kenya
Transmission rates in consecutive pregnancies exposed to single-dose nevirapine in Soweto, South Africa and Abidjan, Cote d'Ivoire
Child mortality according to maternal and infant HIV status in Zimbabwe
Discontinuation and modification of highly active antiretroviral therapy in HIV-infected Ugandans: prevalence and associated factors
June 18, 2007
Hunger, waiting time and transport costs: Time to confront challenges to ART adherence in Africa
Perceptions of community HIV prevalence, own HIV infection, and condom use among teachers in KwaZulu-Natal, South Africa
Home deliveries: implications for adherence to nevirapine in a PMTCT programme in rural Malawi
Haematological safety of perinatal zidovudine in pregnant HIV-1-infected women in Thailand: secondary analysis of a randomized trial
June 4, 2007
Impact and process evaluation of integrated community and clinic-based HIV-1 control: a cluster-randomised trial in eastern Zimbabwe
A group-based intervention to increase condom use among HIV serodiscordant couples in India, Thailand, and Uganda
Effect of age, polymicrobial disease, and maternal HIV status on treatment response and cause of severe pneumonia in South African children: a prospective descriptive study
The impact of daily cotrimoxazole prophylaxis and antiretroviral therapy on mortality and hospital admissions in HIV-infected Zambian children
May 24, 2007
Pregnancy and the risk of HIV-1 acquisition among women in Uganda and Zimbabwe
Treatment interruptions predict resistance in HIV positive individuals purchasing fixed-dose combination antiretroviral theraphy in Kampala, Uganda
Acceptability of male circumcision for prevention of HIV infection in Zambia
Voluntary counselling and testing: uptake, impact on sexual behavior, and HIV incidence in a rural Zimbabwean cohort
May 9, 2007
The Impact of Male Circumcision on HIV Incidence and Cost per Infection Prevented: A Stochastic Simulation Model from Rakai, Uganda
Mother-to-Child Transmission of HIV-1 Infection during Exclusive Breastfeeding in the First 6 Months of Life: An Intervention Cohort Study
Implementation of a Programme for the Prevention of Mother-to-Child Transmission of HIV in a Ugandan Hospital over Five Years: Challenges, Improvements and Lessons Learned
Sex and HIV Education Programs: Their Impact on Sexual Behaviors of Young People throughout the World
April 26, 2007
Evaluation of the Reach and Impact of the 100% Jeune Youth Social Marketing Program in Cameroon: Findings from Three Cross-Sectional Surveys
Acceptance of Anti-Retroviral Therapy among Patients Infected with HIV and Tuberculosis in Rural Malawi Is Low and Associated with Cost of Transport
Quasi-Experimental Evaluation of a National Primary School HIV Intervention in Kenya
Establishing a Workplace Antiretroviral Therapy Programme in South Africa
March 26, 2007
HIV Incidence during a Cluster-Randomized Trial of Two Strategies Providing Voluntary Counselling and Testing at the Workplace, Zimbabwe
Male Circumcision for HIV Prevention in Young Men in Kisumu, Kenya: A Randomised Controlled Trial
Male Circumcision for HIV Prevention in Men in Rakai, Uganda: A Randomised Trial
Reduction of HIV-1 RNA Levels with Therapy to Suppress Herpes Simplex Virus
March 12, 2007
Circumcision for Prevention Against HIV: Marked Seasonal Variation in Demand and Potential Public Sector Readiness in Soweto, South Africa
Antiretroviral Post-Exposure Prophylaxis (PEP) for Occupational HIV Exposure
Hospitalization and Morality among HIV-Infected Children after Receiving HAART
February 20, 2007
Acceptability of Formula-Feeding to Prevent HIV Postnatal Transmission, Abidjan, Côte d'Ivoire: ANRS 1201/1202 Ditrame Plus Study
Effectiveness of an HIV Prevention Program for Secondary School Students in Mongolia
Home-Based Antiretroviral Care is Associated with Positive Social Outcomes in a Prospective Cohort in Uganda
Scaling up HIV Treatment in Peru: Applying Lessons from DOTS-Plus
January 30, 2007
Sustained Benefit from a Long-Term Antiretroviral Adherence Intervention: Results of a Large Randomized Clinical Trial
Adherence to HAART: A Systematic Review of Developed and Developing Nation Patient-Reported Barriers and Facilitators
Antiretroviral Therapy in Resource-Poor Settings: Decreasing Barriers to Access and Promoting Adherence
Efficacy of Interventions in Improving Highly Active Antiretroviral Therapy Adherence and HIV-1 RNA Viral Load: A Meta-Analytic Review of Randomized Controlled Trials
January 11, 2007
Effect of a Structural Intervention for the Prevention of Intimate-Partner Violence and HIV in Rural South Africa: A Cluster Randomised Trial
Effect of Cotrimoxazole on Causes of Death, Hospital Admissions and Antibiotic Use in HIV-Infected Children
Impact of Suppressive Herpes Therapy on Genital HIV-1 RNA among Women Taking Antiretroviral Therapy: A Randomized Controlled Trial
Risk Factors for High Early Mortality in Patients on Antiretroviral Treatment in a Rural District of Malawi
December 22, 2006
Integration of Antiretroviral Treatment within Antenatal Care in Gauteng Province, South Africa
A Review of Female-Condom Effectiveness: Patterns of Use and Impact on Protected Sex Acts and STI Incidence
December 6, 2006
Adherence to Antiretroviral Therapy in a Home-Based AIDS Care Programme in Rural Uganda
Short-Term Effect of a Cultural Adaptation of Voluntary Counseling and Testing Among Female Sex Workers in China: A Quasi-Experimental Trial
A Controlled Study of an HIV/AIDS/STI/TB Intervention with Traditional Healers in KwaZulu-Natal
Measuring the Outcomes of a Comprehensive HIV Care Course: Pilot Test at the Infectious Diseases Institute, Kampala, Uganda
November 16, 2006
Peer-Driven HIV Interventions for Drug Injectors in Russia: First Year Impact Results of a Field Experiment
Impact of a Social Influence Intervention on Condom Use and Sexually Transmitted Infections Among Establishment-Based Female Sex Workers in the Philippines: A Multilevel Analysis
Country-Wide Distribution of the Nitrile Female Condom (FC2) in Brazil and South Africa: A Cost-Effectiveness Analysis
The Cost-Effectiveness of Treating Male Trichomoniasis to Avert HIV Transmission in Men Seeking Sexually Transmitted Disease Care in Malawi
November 3, 2006
A Prospective Study Assessing the Effects of Introducing the Female Condom in a Sex Worker Population in Mombasa, Kenya
The Costs of Treating Curable Sexually Transmitted Infections in Low- and Middle-Income Countries: A Systematic Review
Short-Term Risk of AIDS or Death in People Infected with HIV-1 Before Antiretroviral Therapy in South Africa: A Longitudinal Study
Improving Well-Being Through Psycho-Education Among Voluntary Counseling and Testing Seekers in Nigeria: A Controlled Outcome Study
September 27, 2006
Adherence to Highly Active Antiretroviral Therapy Assessed by Pharmacy Claims Predicts Survival in HIV-Infected South African Adults
Undiagnosed HIV Infection and Couple HIV Discordance Among Household Members of HIV-Infected People Receiving Antiretroviral Therapy in Uganda
Survival Rate and Risk Factors of Mortality Among HIV/Tuberculosis-Co-Infected Patients with and Without Antiretroviral Therapy
Behavioral HIV Risk Reduction Among People Who Inject Drugs: Meta-Analytic Evidence of Efficacy
September 16, 2006
Adherence to Antiretroviral Therapy in Sub-Saharan Africa and North America: A Meta-Analysis
Rapid Scale-Up of Antiretroviral Therapy at Primary Care Sites in Zambia
Rural-to-Urban Migrants and the HIV Epidemic in China
Breastfeeding Plus Infant Zidovudine Prophylaxis for 6 Months vs Formula Feeding Plus Infant Zidovudine for 1 Month to Reduce Mother-to-Child HIV Transmission in Botswana: A Randomized Trial: The Mashi Study
Poste By Kamal Devkota, From Kathmandu
Global Challenges | IANS/Hindustan Times Examines GTZ's Efforts To Educate Congolese Villagers About HIV/AIDS
[Nov 20, 2007]
The IANS/Hindustan Times on Saturday examined the German aid agency GTZ's efforts to educate people living in rural areas of the Democratic Republic of the Congo about HIV/AIDS. GTZ in March launched a mobile sex education caravan to travel hundreds of miles to Maniema, a remote Congolese province with no borders to any other countries and few paved roads. According to the IANS/Times, Maniema has not been highly affected by HIV/AIDS, but the emerging mine industry and influx of workers could create a "new breeding ground" for the disease.
The GTZ project established five stations with different educational components under a mango tree in a village using tree branches and colorful fabric. Setting up under a mango tree aims to appeal to the village's local traditions and make people feel more comfortable about learning the material, the IANS/Times reports. "To bring people together, we found out what is the traditional way to do so. And that's around the mango tree," Achim Koch, project manager of GTZ's youth initiatives in the region, said.
About 10 people visit each station at one time to learn about HIV transmission, prevention and management, as well as different contraceptive methods. The lessons are targeted at youth, particularly young men who were drafted into militia groups during conflict. The learning is interactive and includes games in which participants must describe the risks of HIV in particular situations.
According to the IANS/Times, about 200 people visit the stations daily, and the group has reached more than 16,000 people since it began the project. The United Nations estimates that the country's HIV prevalence is between 1.7% and 7.6% among the general population and that it might be as high as 20% among women in the country's conflict zones (IANS/Hindustan Times, 11/17).
Global Health Literature Digest
These journal articles are selected from a bi-weekly digest produced by the UCSF Institute for Global Health (IGH). The IGH Literature Digest highlights recently published studies of interventions that have one or more of the following aims: to reduce sexual or drug-related risk behaviors, decrease primary or secondary transmission, improve health service delivery and quality of life, or improve HIV treatment and adherence. Studies were either conducted in, or have applications to, resource-limited settings. Summaries and reviewer commentary are the work of IGH authors and have been published here with the permission of IGH.
October 1, 2007
Clinical impact and cost-effectiveness of antiretroviral therapy in India: starting criteria and second-line therapy
Infant feeding in the time of HIV: Assessment of infant feeding policy and programs in four African countries scaling up prevention of mother to child transmission programs
Estimating the number of vertically HIV-infected children eligible for antiretroviral treatment in resource-limited settings
Nursing care of AIDS patients in Uganda
September 10, 2007
Incident and prevalent herpes simplex virus type 2 infection increases risk of HIV acquisition among women in Uganda and Zimbabwe
Cost-effectiveness of on-site antenatal screening to prevent congenital syphilis in rural eastern Cape Province, Republic of South Africa
Continued very high prevalence of HIV infection in rural KwaZulu-Natal, South Africa: a population-based longitudinal study
Maternal HIV infection and placental malaria reduce transplacental antibody transfer and tetanus antibody levels in newborns in Kenya
August 14, 2007
Prevalence of HIV infection in conflict-affected and displaced people in seven sub-Saharan African countries: a systematic review
Flash-Heat Inactivation of HIV-1 in Human Milk: A Potential Method to Reduce Postnatal Transmission in Developing Countries
Antiretroviral durability and tolerability in HIV-infected adults living in urban Kenya
How far will we need to go to reach HIV-infected people in rural South Africa?
July 13, 2007
The cost effectiveness of antiretroviral treatment strategies in resource-limited settings
The protective effect of circumcision on HIV incidence in rural low-risk men circumcised predominantly by traditional circumcisers in Kenya: two-year follow-up of the Kericho HIV cohort study
Risk factors for treatment denial and loss to follow-up in an antiretroviral treatment cohort in Kenya
The impact of HIV treatment on risk behaviour in developing countries: A systematic review
July 2, 2007
HIV, malaria, and infant anemia as risk factors for postneonatal infant mortality among HIV-seropositive women in Kisumu, Kenya
Transmission rates in consecutive pregnancies exposed to single-dose nevirapine in Soweto, South Africa and Abidjan, Cote d'Ivoire
Child mortality according to maternal and infant HIV status in Zimbabwe
Discontinuation and modification of highly active antiretroviral therapy in HIV-infected Ugandans: prevalence and associated factors
June 18, 2007
Hunger, waiting time and transport costs: Time to confront challenges to ART adherence in Africa
Perceptions of community HIV prevalence, own HIV infection, and condom use among teachers in KwaZulu-Natal, South Africa
Home deliveries: implications for adherence to nevirapine in a PMTCT programme in rural Malawi
Haematological safety of perinatal zidovudine in pregnant HIV-1-infected women in Thailand: secondary analysis of a randomized trial
June 4, 2007
Impact and process evaluation of integrated community and clinic-based HIV-1 control: a cluster-randomised trial in eastern Zimbabwe
A group-based intervention to increase condom use among HIV serodiscordant couples in India, Thailand, and Uganda
Effect of age, polymicrobial disease, and maternal HIV status on treatment response and cause of severe pneumonia in South African children: a prospective descriptive study
The impact of daily cotrimoxazole prophylaxis and antiretroviral therapy on mortality and hospital admissions in HIV-infected Zambian children
May 24, 2007
Pregnancy and the risk of HIV-1 acquisition among women in Uganda and Zimbabwe
Treatment interruptions predict resistance in HIV positive individuals purchasing fixed-dose combination antiretroviral theraphy in Kampala, Uganda
Acceptability of male circumcision for prevention of HIV infection in Zambia
Voluntary counselling and testing: uptake, impact on sexual behavior, and HIV incidence in a rural Zimbabwean cohort
May 9, 2007
The Impact of Male Circumcision on HIV Incidence and Cost per Infection Prevented: A Stochastic Simulation Model from Rakai, Uganda
Mother-to-Child Transmission of HIV-1 Infection during Exclusive Breastfeeding in the First 6 Months of Life: An Intervention Cohort Study
Implementation of a Programme for the Prevention of Mother-to-Child Transmission of HIV in a Ugandan Hospital over Five Years: Challenges, Improvements and Lessons Learned
Sex and HIV Education Programs: Their Impact on Sexual Behaviors of Young People throughout the World
April 26, 2007
Evaluation of the Reach and Impact of the 100% Jeune Youth Social Marketing Program in Cameroon: Findings from Three Cross-Sectional Surveys
Acceptance of Anti-Retroviral Therapy among Patients Infected with HIV and Tuberculosis in Rural Malawi Is Low and Associated with Cost of Transport
Quasi-Experimental Evaluation of a National Primary School HIV Intervention in Kenya
Establishing a Workplace Antiretroviral Therapy Programme in South Africa
March 26, 2007
HIV Incidence during a Cluster-Randomized Trial of Two Strategies Providing Voluntary Counselling and Testing at the Workplace, Zimbabwe
Male Circumcision for HIV Prevention in Young Men in Kisumu, Kenya: A Randomised Controlled Trial
Male Circumcision for HIV Prevention in Men in Rakai, Uganda: A Randomised Trial
Reduction of HIV-1 RNA Levels with Therapy to Suppress Herpes Simplex Virus
March 12, 2007
Circumcision for Prevention Against HIV: Marked Seasonal Variation in Demand and Potential Public Sector Readiness in Soweto, South Africa
Antiretroviral Post-Exposure Prophylaxis (PEP) for Occupational HIV Exposure
Hospitalization and Morality among HIV-Infected Children after Receiving HAART
February 20, 2007
Acceptability of Formula-Feeding to Prevent HIV Postnatal Transmission, Abidjan, Côte d'Ivoire: ANRS 1201/1202 Ditrame Plus Study
Effectiveness of an HIV Prevention Program for Secondary School Students in Mongolia
Home-Based Antiretroviral Care is Associated with Positive Social Outcomes in a Prospective Cohort in Uganda
Scaling up HIV Treatment in Peru: Applying Lessons from DOTS-Plus
January 30, 2007
Sustained Benefit from a Long-Term Antiretroviral Adherence Intervention: Results of a Large Randomized Clinical Trial
Adherence to HAART: A Systematic Review of Developed and Developing Nation Patient-Reported Barriers and Facilitators
Antiretroviral Therapy in Resource-Poor Settings: Decreasing Barriers to Access and Promoting Adherence
Efficacy of Interventions in Improving Highly Active Antiretroviral Therapy Adherence and HIV-1 RNA Viral Load: A Meta-Analytic Review of Randomized Controlled Trials
January 11, 2007
Effect of a Structural Intervention for the Prevention of Intimate-Partner Violence and HIV in Rural South Africa: A Cluster Randomised Trial
Effect of Cotrimoxazole on Causes of Death, Hospital Admissions and Antibiotic Use in HIV-Infected Children
Impact of Suppressive Herpes Therapy on Genital HIV-1 RNA among Women Taking Antiretroviral Therapy: A Randomized Controlled Trial
Risk Factors for High Early Mortality in Patients on Antiretroviral Treatment in a Rural District of Malawi
December 22, 2006
Integration of Antiretroviral Treatment within Antenatal Care in Gauteng Province, South Africa
A Review of Female-Condom Effectiveness: Patterns of Use and Impact on Protected Sex Acts and STI Incidence
December 6, 2006
Adherence to Antiretroviral Therapy in a Home-Based AIDS Care Programme in Rural Uganda
Short-Term Effect of a Cultural Adaptation of Voluntary Counseling and Testing Among Female Sex Workers in China: A Quasi-Experimental Trial
A Controlled Study of an HIV/AIDS/STI/TB Intervention with Traditional Healers in KwaZulu-Natal
Measuring the Outcomes of a Comprehensive HIV Care Course: Pilot Test at the Infectious Diseases Institute, Kampala, Uganda
November 16, 2006
Peer-Driven HIV Interventions for Drug Injectors in Russia: First Year Impact Results of a Field Experiment
Impact of a Social Influence Intervention on Condom Use and Sexually Transmitted Infections Among Establishment-Based Female Sex Workers in the Philippines: A Multilevel Analysis
Country-Wide Distribution of the Nitrile Female Condom (FC2) in Brazil and South Africa: A Cost-Effectiveness Analysis
The Cost-Effectiveness of Treating Male Trichomoniasis to Avert HIV Transmission in Men Seeking Sexually Transmitted Disease Care in Malawi
November 3, 2006
A Prospective Study Assessing the Effects of Introducing the Female Condom in a Sex Worker Population in Mombasa, Kenya
The Costs of Treating Curable Sexually Transmitted Infections in Low- and Middle-Income Countries: A Systematic Review
Short-Term Risk of AIDS or Death in People Infected with HIV-1 Before Antiretroviral Therapy in South Africa: A Longitudinal Study
Improving Well-Being Through Psycho-Education Among Voluntary Counseling and Testing Seekers in Nigeria: A Controlled Outcome Study
September 27, 2006
Adherence to Highly Active Antiretroviral Therapy Assessed by Pharmacy Claims Predicts Survival in HIV-Infected South African Adults
Undiagnosed HIV Infection and Couple HIV Discordance Among Household Members of HIV-Infected People Receiving Antiretroviral Therapy in Uganda
Survival Rate and Risk Factors of Mortality Among HIV/Tuberculosis-Co-Infected Patients with and Without Antiretroviral Therapy
Behavioral HIV Risk Reduction Among People Who Inject Drugs: Meta-Analytic Evidence of Efficacy
September 16, 2006
Adherence to Antiretroviral Therapy in Sub-Saharan Africa and North America: A Meta-Analysis
Rapid Scale-Up of Antiretroviral Therapy at Primary Care Sites in Zambia
Rural-to-Urban Migrants and the HIV Epidemic in China
Breastfeeding Plus Infant Zidovudine Prophylaxis for 6 Months vs Formula Feeding Plus Infant Zidovudine for 1 Month to Reduce Mother-to-Child HIV Transmission in Botswana: A Randomized Trial: The Mashi Study
Poste By Kamal Devkota, From Kathmandu
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