The rate of new HIV infections is especially high among gay men recently diagnosed with a rectal sexually transmitted infection (STI), according to research conducted in New York City and published in the online edition of Clinical Infectious Diseases.
The authors compared HIV incidence in both people diagnosed with rectal chlamydia (CT) and/or gonorrhoea (GC) infection at a baseline clinic visit between 2008 and 2010 and closely matched controls who were negative for these infections at their baseline visit. Over two-thirds of both the diagnosed people and the controls reported unprotected anal sex. During follow-up, 7% of men with rectal STIs at the initial clinic visit were diagnosed with HIV, compared to 3% of men without these infections at baseline.
“Our results demonstrate that rectal CT/GC infections are objective markers for identifying persons at an exceptionally high risk for HIV,” comment the authors.
Gay and other men who have sex with men (MSM) are one of the groups most affected by HIV. Almost half of new HIV infections in New York City in 2010 involved gay men, and very high rates of STIs have also been recorded in this population. STIs can cause biological changes that increase susceptibility to infection with HIV.
Unprotected anal intercourse is a well-known risk factor for HIV infection for gay men. The presence of a rectal STI can be considered a marker of high-risk sexual behaviour. Investigators wished to see if recent diagnosis with a rectal chlamydia and/or gonorrhoea was associated with an increased risk of subsequent HIV infection.
Their study population consisted of 276 gay men who were screened for HIV and STIs at the same clinic visit between 2008 and 2010. The men tested HIV negative but all were diagnosed with a rectal STI (chlamydia, n= 177; gonorrhoea, n = 69; both, n = 30). Over two-thirds (69%) reported no or inconsistent condom use and a median of four partners in the previous three months. Most of the rectal infections (70%) were asymptomatic, “underscoring the need for routine rectal screening of patients who report unprotected anal intercourse”.
The participants were matched with 276 controls, gay men who tested negative for both HIV and rectal STIs at a clinic visit in the same period. These controls had a similar HIV risk profile to the diagnosed participants, with 69% also reporting no or inconsistent condom use.
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