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Incidence of Syphilis, Other STIs Rising Steadily in HIV+ MSM of France
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IAS 2015, July 19-22, 2015, Vancouver
Mark Mascolini
New diagnoses of syphilis and other bacterial sexually transmitted infections (STIs) have climbed steadily since the turn of the millennium in men who have sex with men (MSM) in France monitored since they became HIV-positive [1]. Almost 1 in 10 men with a detectable HIV load now gets diagnosed with a bacterial STI every year.
More than half of HIV-positive people surveyed in France in 2010 had already heard of Treatment as Prevention (TasP)--the concept that controlling HIV with antiretroviral therapy sharply lowers risk of HIV transmission. Concern persists that people who know they have an undetectable load--untroubled about passing their HIV to sex partners--will have more condom-free sex. Data cited by ANRS PRIMO researchers who conducted this study indicate that MSM in France account for high proportions of new STIs in the country, including about 90% of new syphilis diagnoses and 90% of new rectal chlamydia cases.
To gauge STI rates in MSM newly infected with HIV, especially in relation to HIV load, the ANRS team conducted this observational analysis. ANRS PRIMO is a national prospective study that enrolls men with primary HIV infection and monitors them every 6 months. Since 2000 PRIMO members have completed a twice-yearly questionnaire on behavior, including sexual behavior.
Researchers counted the number of new STI diagnoses reported by study physicians or MSM since their last visit, focusing on syphilis, gonorrhea, chlamydia, and other suspected bacterial infections. They considered two episodes of the same STI as distinct infections if reported at least 3 months apart for other bacterial infections and at least 1 year apart for syphilis. They used Poisson regression to assess change in STI incidence over time and STI incidence in relation to detectable or undetectable viral load at the study visit preceding the STI.
This analysis involved 1226 MSM monitored in ANRS PRIMO from November 1996 through June 2014. Most men (92%) were born in France, 82% called themselves gay, and 18% considered themselves bisexual. Median age at enrollment measured 35 years and median follow-up 48 months. Overall syphilis incidence stood at 3.61 per 100 person-years, meaning between 3 and 4 of every 100 men got diagnosed with syphilis every year. Incidence of other bacterial STIs combined measured 3.19 per 100 person-years. Incidence of syphilis and other bacterial STIs together came to 6.67 per 100 person-years.
Before 2000 no MSM in this cohort had a reported syphilis diagnosis. Since then, syphilis incidence has climbed 9% yearly (P < 0.0001) to reach 4.92 per 100 person-years in 2013, meaning about 5 of every 100 men got diagnosed with syphilis in 2013. Incidence of other bacterial STIs started climbing by 4% yearly in 1999 (P = 0.006) and reached 4.25 per 100 person-years in 2013.
Incidence of all STIs proved significantly higher in the months after a man had a detectable HIV load than in the months after an undetectable load (7.72 versus 6.08 per 100 person-years, P = 0.02). Since 2010, STI incidence has remained higher after a detectable viral load than after an undetectable viral load (9.53 versus 7.37 per 100 person-years) and that difference approaches statistical significance (P = 0.07).
These findings suggest that men with an undetectable viral load are having less condomless sex than men with a detectable load, hinting that awareness of TasP has not led to reckless sex in men controlling HIV with antiretrovirals--at least not in France. Still, the ANRS PRIMO team urged colleagues to remind MSM that HIV suppression with antiretrovirals does not protect them from acquiring or transmitting other STIs.
Climbing incidence of syphilis and other STIs, the researchers advised, shows that MSM in France continue to have unsafe sex and thus may transmit HIV when they have a detectable viral load.
Reference
1. Champenois K, Seng R, Persoz A, Essat A, Goujard C, Meyer L, ANRS PRIMO Cohort Study Group. Sexually transmitted infection (STI) incidence in men who have sex with men (MSM) followed since primary infection stage in the French ANRS-PRIMO cohort. IAS 2015. 8th Conference on HIV Pathogenesis, Treatment and Prevention. July 19-22, 2015. Vancouver. Abstract WEPEC634.
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