AEGiS-15IAC: [LbOrC24] PREVALENT HSV-2 INFECTION AND RISK FOR HIV SEROCONVERSION IN A COHORT OF KENYAN FEMALE SEX WORKERS ENROLLED IN A RANDOMIZED CONTROLLED TRIAL OF ANTIBIOTIC CHEMOPROPHYLAXIS TO REDUCE HIV INCIDENCE

15th International AIDS Conference

Bangkok, Thailand — July 11-July 16, 2004

[LbOrC24] PREVALENT HSV-2 INFECTION AND RISK FOR HIV SEROCONVERSION IN A COHORT OF KENYAN FEMALE SEX WORKERS ENROLLED IN A RANDOMIZED CONTROLLED TRIAL OF ANTIBIOTIC CHEMOPROPHYLAXIS TO REDUCE HIV INCIDENCE

Int Conf AIDS. 2004 Jul 11-16;15:Abstract No. LbOrC24

S Moses¹, R Kaul², J Kimani³, K Fonck⁴, N Nagelkerke¹, F Keli³, K MacDonald², I Maclean¹, J Bwayo³, A Ronald¹, M Temmerman⁴
¹University of Manitoba, Winnipeg, Canada; ²University of Toronto, Toronto, Canada; ³University of Nairobi, Nairobi, Kenya; ⁴University of Ghent, Ghent, Belgium

OBJECTIVE: Bacterial sexually transmitted infections (STIs) are common in female sex workers (FSWs) and are often asymptomatic. Antibiotic prophylaxis may reduce STI acquisition and thus reduce risk of HIV infection. We conducted a clinical trial in an FSW cohort to test this hypothesis, and recently examined the association between herpes simplex type 2 (HSV-2) infection and HIV acquisition in the cohort.

METHODS: HIV seronegative FSWs in Nairobi were randomly assigned to receive either 1 gm of azithromycin monthly or placebo, in double-blind fashion. All women were counselled to reduce STI risk and were provided with free condoms. Urine was tested monthly for bacterial STIs, and full behavioural and STI work-ups were performed at 6-monthly intervals, including HSV-2 serology.

RESULTS: Of 466 FSWs enrolled, 236 were randomized to the placebo group and 230 to the azithromycin group. Total follow-up was 969 person-years (PYs) and there were 35 incident HIV infections, for an annualized HIV incidence of 3.6 per 100 PYs. Incidences of STIs in the treatment and control groups have been reported previously. Gonorrhea, chlamydia and trichomoniasis incidences were significantly lower in the treatment arm than the placebo arm, but there was no difference in HIV incidence between the two arms. Overall, 73% of women were HSV-2 antibody seropositive at baseline, and there was no difference in seropositivity rates at baseline between the two study arms. HIV incidence was 10.2 per 100 PYs among FSWs who were HSV-2 positive at baseline compared to 1.7 per 100 PYs in FSWs who were HSV-2 negative (multivariate RR 6.3, 95% CI 1.5 - 27.1, P < 0.01).

CONCLUSIONS: Monthly azithromycin prophylaxis reduced the incidence of several STIs in this cohort, but had no impact on HIV incidence. The strong association observed between incident HIV infection and pre-existing HSV-2 infection suggests that HSV-2 may have been an important cofactor in HIV-1 acquisition, and supports the rationale for trials of HSV-2 suppression as an HIV-1 prevention strategy in high risk populations.

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