In high-income countries such as Canada, Australia and the U.S. and regions such as Western Europe, HIV infections continue to spread, particularly among men who have sex with men (MSM).
New York City was one of the first urban regions hard hit by the emerging HIV epidemic in the 1980s. Research in that city has revealed that in 2010 nearly 50% of new HIV/AIDS diagnoses were among MSM.
Public health workers in New York City have found that many MSM have a large burden of sexually transmitted infections (STIs), such as chlamydia, gonorrhea and syphilis.
Numerous studies have found a link between the presence of an STI and increased risk for becoming infected with HIV. STIs can do this because they can injure the delicate tissue on or inside the anus, genitals, mouth and throat. STIs can also cause inflammation. The sores (sometimes painless) or lesions associated with STIs in these tissues can provide a point of entry for HIV (and other germs) into the body.
Focus on STIs and Their Impact on HIV
Researchers in New York City conducted an analysis of data collected from STI clinics over the past several years. In those clinics, people who sought care were offered rapid HIV testing. MSM whose rapid test results were negative were offered more accurate tests that can identify HIV's genetic material.
MSM who disclosed that they had unprotected receptive anal intercourse were also offered STI testing (for chlamydia and gonorrhea) using rectal swabs.
The researchers analysed data collected between January 2008 and March 31, 2010. They compared rates of HIV infection among 552 MSM with and without rectal STIs. Participants were roughly the same age and had similar risk behaviours.
The researchers found that having a rectal STI significantly increased the risk of becoming infected with HIV. That is, one in 15 MSM who had a rectal STI and who were initially HIV negative were subsequently diagnosed with HIV, usually within a year of the STI diagnosis. Troublingly, most of the men were unaware that they had rectal STIs because in more than 70% of cases such infections were symptom free.
Results: High Rates of Hidden STIs
According to the researchers' calculations, about 7% of 276 MSM who had rectal STIs became HIV positive each year of the study. In contrast, about 3% of the 276 other MSM who did not have rectal STIs became infected with HIV each year of the study. This difference in HIV infection rates was statistically significant; that is, not likely due to chance alone. Overall, being diagnosed with a rectal STI increased the risk of subsequent HIV infection more than two-fold.
New HIV infections were very high among some subgroups, as follows:
- MSM who were black: 15% became HIV positive
- MSM who had both rectal chlamydia and gonorrhea: 11% became HIV positive
- MSM who were younger than 20 years old: 10% became HIV positive
According to the researchers, MSM who were black and diagnosed with rectal STIs were five-fold more likely to subsequently develop HIV compared to white MSM with both rectal STIs.
Researchers also tested participants for early-stage syphilitic infection but found that although relatively common it did not appear to play a statistically significant role in the spread of HIV. However, other studies have found that syphilis does play a role in the growing HIV epidemic, particularly in MSM.
Although not a focus of the present New York study, other studies have found that the use of alcohol and/or party drugs by some MSM may play a role in enabling unsafe behaviours, rendering users vulnerable to HIV.
Bear in Mind
The finding that many cases of rectal STIs were symptom free meant that the men were not aware that they had these infections. As a result, the New York City researchers stated that their results "underscore the need for routine rectal screening of patients who report unprotected anal intercourse."
For Healthcare Providers
The researchers encourage doctors and nurses to do the following:
"Take a nonjudgmental and confidential sexual history that ascertains the sex of a patient's sex partners and anatomic sites of sexual exposure."
Furthermore, they add that healthcare providers' encounters with patients are an ideal time to provide education about risk factors for becoming infected with HIV. Such encounters are an opportunity to intervene in order to decrease HIV risk behaviour.
Barriers to Care
The New York City researchers also recognized growing barriers to STI care in their region, such as the following:
- insufficient time for healthcare providers to spend with patients
- not enough staff available to counsel patients and contact sex partners to offer them STI and HIV testing
- the lack of an approved simple rapid test to detect chlamydia and gonorrhea in oral and rectal swab samples
Targeted Prevention Efforts
The researchers note that MSM who have rectal STIs could be targeted for counselling about receiving pre-exposure prophylaxis (PrEP). The main part of PreP interventions (in addition to safer sex counselling and frequent testing for STIs and HIV) involves the use of two anti-HIV drugs -- tenofovir and FTC -- co-formulated in a single pill called Truvada. In clinical trials with MSM, daily Truvada compared to placebo reduced the overall risk of HIV infection by 44%. Truvada's preventive ability was greater in MSM who took the pill exactly as directed.
In their report, published in the journal Clinical Infectious Diseases, the New York City researchers did not mention another HIV prevention possibility called TasP -- Treatment as Prevention. The idea behind TasP is to offer HIV testing widely in a city or region. People who test positive can receive counselling and a swift referral to a clinic for discussion about the benefits of early initiation of HIV treatment. By starting treatment relatively early in the course of HIV infection, the immune system can be preserved and enhanced. Furthermore, treatment options recommended for initiating HIV therapy today in high-income countries are relatively well tolerated, very effective and can be taken once or twice daily. Early treatment should also help maintain or improve a person's quality of life in the medium- and long-term. All of these changes benefit the individual with HIV. Additionally, treatment can reduce the amount of HIV in the blood and genital fluids, and thereby helps to decrease someone's sexual infectiousness. This latter effect benefits the community and society.
Results from a study in British Columbia suggest that TasP can help to greatly reduce the spread of HIV among heterosexuals and people who inject street drugs. However, in that study, researchers found that TasP had less significant effects on HIV transmission in MSM.
For the Future
Although the New York City study is imperfect -- it was observational and retrospective in nature -- its findings are supported by a growing body of research that exposes the critical role that STIs play in amplifying the spread of HIV. Therefore, efforts at intensifying STI prevention, testing and treatment are useful not only because they improve the well-being of sexually active adults but also because they can help prevent the spread of HIV. Such efforts -- together with increased education about the correct and consistent use of condoms, screening for and treatment of mental health issues (including addiction to alcohol and other substances) -- need to be implemented to help bring STIs, including HIV, under control.
STIs: What Role Do They Play in HIV Transmission? -- Prevention in Focus
Treatment as Prevention: Do the Individual Prevention Benefits Translate to the Population Level? -- Prevention in Focus
Pre-Exposure Prophylaxis (PrEP) -- CATIE Fact Sheet
The Vancouver STOP Project -- Programming Connection
- Sullivan PS, Hamouda O, Delpech V, et al. Reemergence of the HIV epidemic among men who have sex with men in North America, western Europe, and Australia, 1996-2005. Annals of Epidemiology. 2009; 19: 423-431.
- Kirby T, Thornber-Dunwell M. New HIV diagnoses in London's gay men continue to soar. Lancet. 2013 Jul 27;382(9889):295.
- Kirby T, Thornber-Dunwell M. High-risk drug practices tighten grip on London gay scene. Lancet. 2013 Jan 12;381(9861):101-2.
- Grov C, Rendina HJ, Ventuneac A, et al. HIV risk in group sexual encounters: An event-level analysis from a national online survey of MSM in the U.S. Journal of Sexual Medicine. 2013 Sep;10(9):2285-94.
- Matser A, Vanhommerig J, Schim van der Loeff MF, et al. HIV-infected men who have sex with men who identify themselves as belonging to subcultures are at increased risk for hepatitis C infection. PLoS One. 2013;8(3):e57740.
- Witt MD, Seaberg EC, Darilay A, et al. Incident hepatitis C virus infection in men who have sex with men: a prospective cohort analysis, 1984-2011. Clinical Infectious Diseases. 2013 Jul;57(1):77-84.
- Salado-Rasmussen K, Katzenstein TL, Gerstoft J, et al. Risk of HIV or second syphilis infection in Danish men with newly acquired syphilis in the period 2000-2010. Sexually Transmitted Infections. 2013 Aug;89(5):372-6.
- Montaner JSG, Lima VD, Barrios R, et al. Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study. Lancet. 2010; 376: 532-539.
- Phillips AN, Cambiano V, Nakagawa F, et al. Increased HIV incidence in men who have sex with men despite high levels of ART-induced viral suppression: analysis of an extensively documented epidemic. PLoS One. 2013; 8: e55312.
- Birrell PJ, Gill ON, Delpech VC, et al. HIV incidence in men who have sex with men in England and Wales 2001-10: a nationwide population study. Lancet Infectious Diseases. 2013; 13: 313-318.
- Pathela P, Braunstein SL, Blank S, et al. HIV incidence among men with and those without sexually transmitted rectal infections: estimates from matching against an HIV case registry. Clinical Infectious Diseases. 2013 Oct;57(8):1203-9.