AEGiS-13IAC: A randomized, placebo-contolled trial of monthly azithromycin to prevent sexually transmitted infections (STI) and HIV in Kenyan female sex workers (FSWs): preliminary findings.

13th International AIDS Conference

Durban, South Africa - July 9-July 14, 2000

A randomized, placebo-contolled trial of monthly azithromycin to prevent sexually transmitted infections (STI) and HIV in Kenyan female sex workers (FSWs): preliminary findings.

Int Conf AIDS 2000 Jul 9-14; 13:(abstract no. ThOrC763)

Moses S, Kaul R, Nguge EN, Kimane S, Bwayo SS, Fonck K, MacDonald KS, Temmerman M, Plummer FA
S. Moses, University of Manitoba, Dept. of Medical Microbiology, 730 William Avenue, Winnipeg, Manitoba R36, Canada, Tel.: +1 204 789 3357, Fax: +1 204 789 3926, E-mail: smoses@cc.umanitoba.ca

BACKGROUND: STI are common in FSWs, increase HIV susceptibility, and are often asymptomatic and difficult to treat promptly. Appropriate antibiotic prophylaxis may therefore reduce STI acquisition, thus reducing risk of HIV infection. We designed a clinical trial to assess if antibiotic prophylaxis reduces HIV acquisition in FSWs.

METHODS: In May 1998 we established a cohort of HIV seronegative FSWs in Nairobi, half of whom are randomly assigned to receive 1 gram of azithromycin monthly and the other half a placebo, in a double-blind fashion. All women are also counseled to reduce risk for STI by reducing numbers of partners and consistently ensuring that partners use male condoms. Risk behaviour is assessed at baseline and at 3-monthly follow-up visits. Full physical exams, including STI work-ups and treatment, are performed at baseline and at 6-monthly intervals. Medical care is given to all women during follow-up visits and whenever they seek medical attention.

RESULTS: By September 1999, 253 women had been enroled. At baseline, they reported a mean of 14.7 sex partners per week, 33% reported never using condoms in the past month and 19% always using condoms. At their most recent follow-up visit, they reported a mean of 5.1 sex partners per week and 57% reported always using condoms in the past month. 29% reported no condom use in the past month, but 31% of these women reported no sex partners during that period. Reductions in partners and increases in condom use were statistically significant (P > 0.001). Three women sero-converted to HIV-1 in approximately 178 person-years (PYs) of follow-up, for an annualized HIV incidence of 1.7 per 100 PYs. Incidence of gonorrhea, chlamydia and syphilis were 5.2%, 7.4% and 3.8% respectively. No genital ulcers (GUs) were observed on follow-up.

CONCLUSION: HIV incidence in this cohort of high-risk women is much lower than anticipated, likely due to a combination of behavioural change after enrolment and the low STI incidence, particularly GUs. We anticipate needing to increase the planned sample size to reach the study endpoints. Other HIV prevention studies such as vaccine trials will face similar challenges, as successful promotion of condom use and other safer sex practices in high-risk individuals, along with effective STI treatment, greatly reduces risk for HIV acquisition.

Keywords: AEGIS, HIV Infections, Condoms, Azithromycin, Safe Sex, Incidence, HIV-1, Risk-Taking, Acquired Immunodeficiency Syndrome, Sexual Partners, Condoms, Female, HIV Seropositivity, Gonorrhea, Syphilis, Human, Female, Male
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ThOrC763