In the early years of the HIV epidemic in Africa, female sex workers (FSWs) were identified as a high-prevalence, high-incidence, core group among whom the extraordinary prevalence of other sexually transmitted infections (STIs) facilitated transmission of the virus to their clients, who then infected low-risk women not involved in the sex trade. In resource-poor settings, control of Neisseria gonorrhoeae (NG) and Chlamydia trachomatis (CT) among FSWs is difficult. The purpose of this study is to determine whether periodical antibiotic treatment (PAT) is effective in controlling these infections among West African FSWs.

The study is designed as a cluster-randomized double-blind placebo-controlled trial conducted in West Africa. The study population consists of "seaters" FSWs who work from their homes in well-defined areas. Clusters will be paired according to their size and demographic characteristics of FSWs and clients. Within each pair, one cluster will be randomly allocated to the intervention and the other to the placebo group.

At enrollment, participants will be interviewed, a pelvic examination performed, cervical swabs obtained for NG and CT polymerase chain reaction (PCR), and current cervicitis or vaginitis managed syndromically. Blood specimens will be obtained for HIV testing. All participants will be given free condoms and counseled on risk reduction.

Monthly follow-up will be conducted within FSW communities, alternating with clinic visits where cervical samples will be collected. Study drugs (azithromycin 1 g and ciprofloxacin 500 mg, and their identical placebos) will be distributed every month according to a predefined schedule: directly-observed intake of azithromycin at months 1, 4 and 7, and ciprofloxacin at months 2, 3, 5, 6, 8 and 9.

Data will be analyzed with SAS. The investigators will assess the time trends in NG and CT prevalence separately in both study groups using χ2-for-trend.

"Seaters" are older, more stable, better organized, and have a much higher prevalence of HIV infection than FSWs who roam the streets or part-time sex workers. These communities (from 3 to 114 FSWs per site) will be aggregated into 18 clusters (one cluster was composed of 1-10 FSW communities) based on geographical proximity. Over a one-year period, FSWs from these clusters presenting to dedicated clinics will be invited to participate. In addition, field workers will visit FSWs at home or at prostitution sites to provide information about the trial and seek participation.

Clusters will be paired according to their size and demographic characteristics of FSWs and clients. Within each pair, one cluster will be randomly allocated to the intervention and the other to the placebo group using pre-coded envelopes. With an average of 35 FSWs per cluster, the required number of cluster pairs is estimated at 8.7 to detect a 50% reduction in NG prevalence, assuming a baseline prevalence of 25%, 80% power and 5% alpha error.

Inclusion Criteria:

• Female sex worker (seater) from one of the selected clusters

Exclusion Criteria:

• Allergy to study drugs
• Pregnancy
• Intention to leave the city within the next 3 months