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.
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.
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.
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
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
Both the diagnosed participants
and controls were followed for at least one year.
During a total of
464 person-years of follow-up, 11% of men with a rectal STI at baseline were
diagnosed with HIV, an annual HIV incidence rate of 11%. HIV incidence was
especially high among some groups with rectal STIs. These included black men
(15%); men with both chlamydia and gonorrhoea (10%); and those aged under 20
group participants contributed 474 person-years of follow-up. A total of twelve
individuals (4%) were diagnosed with HIV, an annual incidence rate of (3%).
therefore calculated that men with rectal STIs were significantly more likely
to be diagnosed with HIV during follow-up (relative risk, 2.58; 95% CI,
treating rectal infections may reduce HIV incidence, to the extent rectal STDs
increase biological susceptibility to HIV infection through epithelial erosions
and alteration in host immune defences,” the authors conclude. “Rectal
infections, as markers of behavioural risk, can be used to identify a subset of
patients who may benefit from intensive risk reduction counselling and other
interventions designed to reduce the risk of HIV transmission.”