Risk factors and HIV seropositivity among injecting drug users in Bangkok.

Bangkok experienced an extremely rapid spread of HIV infection among drug injectors in 1987 and 1988. This study examines risk factors for HIV infection and deliberate risk-reduction efforts by drug injectors. Two subsamples of injecting drug users were recruited in November 1989, a group in drug-use treatment (n = 342) and a group new to the treatment system (n = 259). Subjects were interviewed about AIDS risk behavior, and a blood sample was collected for HIV testing. Seroprevalence was 39 and 27% in the in-treatment sample and the new-to-treatment sample, respectively. The in-treatment sample seroprevalence rate is similar to rates observed 6 and 12 months earlier. Three factors were independently associated with HIV infection: subsample, having been in prison, and sharing injection equipment with two or more individuals in the previous 6 months. Deliberate risk reduction was reported by 92% of individuals, with 59% reporting that they had stopped sharing injection equipment. It appears that large-scale risk reduction has greatly slowed HIV transmission among drug injectors in Bangkok.