After prior consultations with community leaders, public meetings were held to inform the community of the planned study. Volunteers aged 18-45 years were then invited to take part in the study after written informed consent was obtained in the presence of the principal investigator. Prior to the start of the screening exercise, the investigators checked the age and identity of each volunteer and conducted pre-HIV test counselling. Screening involved a thorough physical examination, blood sampling for haematological (full blood count, packed cell volume [PCV]), renal (plasma creatinine) and hepatic (alanine aminotransferase) tests and HIV 1 and 2 testing by ELISA. All eligible volunteers were issued unique study numbers and photo identification cards.