01 Set High HIV incidence in MSM following an early syphilis diagnosis: is it time for PrEP in populations at highest risk?

Nicolò Girometti

Objectives. Weighing the impact of sexually transmitted infections in MSM in terms of future HIV acquisition would permit to implement targeted interventions to tackle onward HIV transmission. Incidence for HIV and other STIs following an early syphilis diagnosis in MSM was evaluated.
Methods. We conducted a retrospective case-note review of MSM who were treated for primary, secondary and early latent syphilis over 6 months. Number of sexual health screenings and STIs diagnosed (chlamydia, gonorrhoea, syphilis, HIV and HCV) were prospectively analyzed. We calculated 95% exact CIs for incidence rates using the Poisson distribution.
Results. 206 MSM were diagnosed with early syphilis: 110 HIV-negative, 96 HIV-positive. For 110 HIV-negative MSM, median age was 32 years; median number of sexual partners in last 3 months was 4. Reported drug use in the previous month was 38%; 19% had injected drugs. Syphilis stage was primary (31%), secondary (25%), early latent (45%).Up to February 2016, total follow-up was 144 person-years. 12 (11%) were newly diagnosed HIV-positive. HIV incidence was 8.3 (95% confidence interval, CI 4.2–14) per 100 person-years follow-up (PYFU). Incidence of rectal STIs was: rectal chlamydia, 27 PYFU (CI 19–36); rectal gonorrhoea, 33 HPYFU (CI 25–44); syphilis re-infection, 10 PYFU (CI 5.7–17). Testing frequency and median number of partners were comparable in the two groups.
Conclusions. Early syphilis diagnosis carries a high risk of future HIV seroconversion. Prevention measures such as pre-exposure prophylaxis may be very beneficial in this patient group to prevent further diffusion of HIV.