July 23, 2012 — A new series of 6 articles, 4 comments, and a viewpoint, all published online July 20 in the Lancet, addresses HIV infection and AIDS in men who have sex with men (MSM). In this population, the HIV epidemic continues to grow globally in countries of all incomes, despite significant progress overall in the last 20 years regarding prevention and treatment. Publication of the series coincides with the AIDS 2012: XIX International AIDS Conference, which began July 22.
Topics covered in the series and in a related news conference held July 19 at Kaiser Family Health Foundation in Washington, DC, include:
factors driving the HIV epidemic among MSM, such as the biology of HIV transmission in anal sex, features of MSM networks, and behavioral factors;
the need for improved interaction between MSM and their health system;
the need for leadership and community among MSM;
treatment-as-prevention, preexposure prophylaxis, and other strategies to reduce the infectiousness of HIV, applicable not only to MSM but potentially to other populations affected by the HIV epidemic;
unique global challenges facing black MSM, who worldwide are 15 times more likely to have HIV, who in the United States and United Kingdom are even more likely than white MSM to have HIV, and who in African and Caribbean countries that criminalize homosexuality are twice as likely to have HIV;
the need for all countries to comprehensively address the HIV burden in MSM, including universal availability of condoms and lubricant; and
lowered costs of antiretrovirals in high-income countries to facilitate treatment as prevention.
The first article in the Lancet series, by Chris Beyrer, MD, from Johns Hopkins Bloomberg School of Public Health in Baltimore, Maryland, and colleagues, describes the biology of HIV transmission in anal sex as well as behavioral factors and MSM network features driving the global HIV epidemic among MSM.
"Unfortunately, the bad news is that while we have seen overall a decline in HIV in many populations and in many affected countries, the trajectories of the HIV epidemic among MSM are very different," Dr. Beyrer said in a podcast interview with the Lancet. "They are continuing to expand in many countries, including the United States, where the only population in which HIV rates are rising is young MSM."
HIV prevalence among MSM exceeds 15% in the United States, Spain, Chile, Thailand, Malaysia, South Africa, and various other African and Caribbean nations. By region, the highest prevalence of HIV in MSM is in the Caribbean (25.44%), Sub-Saharan Africa (17.73%), and North America (15.35%).
Despite the availability and widespread use of highly active antiretroviral therapy (HAART) in many high-income settings in Australia, France, the United Kingdom, and the United States, HIV infection rates have increased in MSM while declining in other populations. Since 2001, HIV infections in MSM have increased about 8% per year in the United States.
Among MSM, known risk factors for HIV infection include unprotected receptive anal intercourse, high frequency of male partners, large number of lifetime male partners, injection drug use, high viral load in the index partner, black race (in the United States), and use of amphetamine-like substances and certain other noninjectable drugs.
However, Dr. Beyrer and colleagues conclude that these factors are insufficient to explain the reemergent HIV epidemics among MSM while prevalence is waning in other populations. A key factor is receptive anal sex, which has a high per act (estimated at 1.4%) and per partner risk for HIV transmission — approximately 18-fold greater than that estimated for penile–vaginal intercourse.
Risks are lower for insertive than for receptive anal sex, but role reversal is common in MSM networks, so an MSM infected in a receptive role may then be the insertive partner and infect someone else. Statistical modeling suggested that the 5-year cumulative HIV incidence in MSM would be reduced by from 80% to 98% if the HIV transmission probability of receptive anal sex were similar to that associated with unprotected vaginal sex.
In high-prevalence settings, limiting MSM to either insertive or receptive roles (50% for each, as in heterosexual networks) would reduce 5-year cumulative HIV incidence by from 19% to 55%. New HIV infections could also be reduced by an estimated 29% to 51% if unprotected anal sex currently occurring in casual partnerships instead occurred in long-term partnerships.
Compared with heterosexuals, MSM are much more likely to be infected with multiple HIV strains and to have dramatically greater HIV viral diversity. Coupled with more rapid spread of HIV through MSM networks, these factors hinder development of vaccines and other biomedical approaches to prevention.
Treatment as prevention, preexposure prophylaxis, and other strategies to lower infectiousness will likely be essential to reducing HIV transmission among MSM. These may also include HAART for HIV-positive MSM, use of a rectal microbicide, or successful treatment for prevalent HIV infections.
"The high transmission probability, high force of infection, and potent effect of high HIV prevalence mean that interventions to reduce infectiousness, such as HAART for MSM living with HIV, will be needed to control epidemics of HIV," Dr. Beyrer commented in a slide presentation at the July 19 news conference. "HIV remains uncontrolled among MSM in 2012. These results demand reinvigorated effort, new approaches grounded in biology and epidemiology, and comprehensive efforts to reduce the structural risks that aid and abet HIV spread among these men."
Combined Prevention Efforts
The third article in the Lancet series, by Patrick S. Sullivan, PhD, from the Rollins School of Public Health at Emory University in Atlanta, Georgia, and colleagues, explains that preexposure prophylaxis and other combined prevention efforts are likely to reduce HIV transmission in MSM. The authors call for trials to test this hypothesis.
"Using HIV prevention technologies we have today, we could prevent a quarter of new infections among MSM globally in the next decade," Dr. Sullivan noted in the slide presentation.
The initial, somewhat effective, strategy employed when the HIV epidemic first emerged consisted of behavioral interventions designed to reduce unprotected anal intercourse and other high-risk behaviors in MSM. Although this approach did not reduce HIV transmission, recent findings and modeling suggest that adding biomedical interventions to behavioral interventions could reduce new cases of HIV infection among MSM by up to 25%.
In addition to factors cited in Dr. Beyrer's paper, challenges in HIV prevention among MSM include failure of certain governments and healthcare providers to acknowledge male–male sex, discrimination, lack of services, and syndemic factors (namely, factors that combine with other factors to heighten the risk of HIV transmission, such as substance abuse).
"In most parts of the world, restricted resources and legal barriers complicate the effective provision of HIV prevention services for MSM," the study authors write. "Resources are scarce for HIV prevention services in MSM and scale-up is problematic. Available interventions are insufficient, largely untested in most developing countries, and not sufficiently tailored to MSM."
These multiple, varied challenges mandate a combination of interventions. Although condom use lowers the risk for HIV transmission to a receptive partner by at least 80%, use may be inconsistent and condoms may break.
Because recent research suggests that preexposure prophylaxis in HIV-negative MSM lowers the rate of new infections by 44% compared with placebo, the US Food and Drug Administration has provisionally recommended antiretroviral treatment for this indication.
Other interventions to reduce new infections as part of a combination strategy include:
an educational and informational campaign to improve treatment adherence for all persons with HIV;
HIV testing to identify new infections;
circumcision;
diagnosis and treatment of other sexually transmitted infections; and
group and individual therapy and other behavioral interventions.
Although implementing these interventions will be technically difficult and expensive, modeling suggests that about 11% to 29% of future HIV infections could be prevented during a 10-year period. The investigator applied these models, which assumed 40% coverage of oral preexposure prophylaxis, 40% coverage of antiretroviral treatment, and increased condom usage, to HIV prevention in the United States, Peru, India, and Kenya.
"Proof-of-concept studies of combination prevention approaches should be followed by large, multicentre prevention trials of promising packages," the study authors write. "Alteration of the trajectory of new HIV infections in MSM will necessitate a lot of work. New prevention approaches, increasing acknowledgment of HIV challenges in MSM worldwide, and emphasis on research and programmes for MSM in low-income and middle-income countries are promising signs."
The Role of Activism
The fourth comment in the series, by Jack Killen, MD, from the National Center for Complementary and Alternative Medicine, National Institutes of Health, and colleagues, reviews the history of MSM, AIDS research activism, and the development of antiretroviral therapy.
AIDS activism has facilitated basic and clinical HIV/AIDS research initiatives and implementation of HIV/AIDS prevention and management.
"Despite many advances in HIV treatment and prevention, however, the global burden remains enormous, and the vast majority of infected and at-risk individuals are not MSM," the commentators write. "It is essential that MSM continue to use their energy, experience, and expertise to argue for substantial scale-up for all populations of the delivery of proven interventions such as antiretrovirals for treatment and prevention, studies to better understand and manage HIV-associated co-morbidities and co-infections, and resources to address unanswered scientific questions in the search for an HIV cure and vaccine. The goal of controlling and ultimately ending the HIV/AIDS epidemic will be realised more rapidly and completely through strategies including involvement at every level that were so successfully pioneered by gay men in the early days of AIDS activism."
The Center for Public Health and Human Rights at Johns Hopkins, the Foundation for AIDS Research, and the Bill & Melinda Gates Foundation supported Dr. Beyrer's report. The Johns Hopkins Center for AIDS Research provided partial support to Dr. Beyrer. The authors on this report have disclosed no relevant financial relationships. Some of the authors of Dr. Sullivan's paper were supported by the National Institutes of Health, the Emory Center for AIDS Research, Prevention Umbrella for MSM in the Americas (National Institute of Allergy and Infectious Diseases), the American Foundation for AIDS Research, the International AIDS Vaccine Initiative, and/or Avahan (the Indian initiative of the Bill & Melinda Gates Foundation). The authors on this report have disclosed no relevant financial relationships. The authors of Dr. Killen's comment have disclosed no relevant financial relationships.
Lancet. Published online July 20, 2012. Beyrer full text, Sullivan summary, Comment full text
Medscape Medical News © 2012 WebMD, LLC
Send comments and news tips to news@medscape.net.
Cite this: Lancet Series Covers HIV/AIDS in Men Who Have Sex With Men - Medscape - Jul 23, 2012.
Comments