Risk factors of HIV-1 infection among female prostitutes in Khon Kaen, Northeast Thailand.

HIV infection has increased to epidemic proportions in Thailand since 1987. There have been separate epidemics among population groups at high risk of infection and significant increases in different localities. The northeast region of Thailand has been affected by the epidemic since early 1989. The purpose of this study was to identify factors associated with HIV transmission among prostitutes during an early phase of the epidemic in the regional center of Khon Kaen. Three hundred and fifty-six prostitutes known to work in the urban area of Khon Kaen (Ampur Muang) in November 1990 were included in the study. Prostitutes were divided into two groups according to the type of place where they worked: direct prostitutes (in brothels, n = 217) and indirect prostitutes (in massage parlors, n = 139). The prevalence of HIV infection was found to be 12% among direct prostitutes and 2% among indirect prostitutes. Four variables were significantly associated with HIV infection after adjusting for confounders by logistic regression analysis: previous work in an area of high HIV prevalence, working in Khon Kaen less than one month, a low price charged for sex and using injectable contraceptives. Follow-up investigations are currently being carried out to explore in detail the association between the use of injectable contraceptives and HIV infection.