Objectives: 1) accurately measure alcohol and drug use, especially amphetamine-type stimulants (ATS) and HIV prevalence, among female sex workers (FSW) and male clients of FSW in Preah Sihanouk Province, Cambodia, and; 2) assess the synergy between alcohol and/or drug exposures and HIV risks according to the type of sex work venues.

Design: A cross-sectional study among 100 FSW and 100 male clients in Preah Sihanouk Province, Cambodia. Half of the FSW (n=50) will be recruited in entertainment/drinking establishments (karaoke bars, beer gardens, and nightclubs) and the other half (n=50) in non-entertainment sex work venues (brothels, parks, streets, guest houses). Clients of FSW will also be recruited directly at entertainment/drinking establishments (n=50) and sex work venues (n=50). After an informed consent process, participants will be tested for HIV using rapid testing. Urine samples will be taken for drug toxicology. Dried blood samples (DBS) will be collected to detect heavy alcohol consumption using Phosphatidylethanol (PEth), a biomarker of alcohol intake. Vaginal samples will be collected from women to test for prostate specific antigen (PSA), a marker of recent unprotected sexual intercourse. A standardized questionnaire will be administrated to collect data on socio-demographics and sexual, alcohol and drug exposures. Results from this study will provide important preliminary data for a larger study aimed at reducing HIV risks in FSW and male clients in Cambodia.