WAS THE 1988 HIV EPIDEMIC AMONG BANGKOKS INJECTING DRUG-USERS A COMMON SOURCE OUTBREAK

Objective: To describe and understand the genesis of the explosive 198 8 HIV epidemic among Thai injecting drug users (IDU) in Bangkok. Desig n: Two cross-sectional HIV seroprevalence sample surveys (SP-1 and SP- 2) of drug users, including IDU at various stages of treatment. SP-1, a 10-week estimate of prevalence, was conducted by the Bangkok Metropo litan Administration (BMA) in their detoxification clinics from 5 Janu ary to 7 March 1988. SP-2 estimated prevalence in 1 week, 12-15 Septem ber 1988, in the same 18 BMA clinics. Both surveys included an adminis tered questionnaire that gathered demographic and behavioral informati on. Methods: Analysis of HIV prevalence by clinic in both SP-1 and SP- 2, and the relationships between demographic data, behavioral variable s, arrest history and HIV positivity in SP-1. Results: Data from indiv idual clinics in SP-1 show significant increases in HIV prevalence amo ng IDU sampled from early February 1988. Of IDU sampled in five 'early ' clinics before 9 February, 2% were positive; in the 13 'late' clinic s sampled from 9 February until 7 March, 27% were positive. By Septemb er 1988, however, the early and late clinics were no longer heterogeno us for HIV prevalence. For current IDU, HIV-positivity was associated with the sharing of injection equipment in SP-1 [odds ratio (OR), 1.82 ; 95% confidence limits (CL), 1.31-2.53] and recent jail or prison sta y (OR, 2.1 5; 95% CL, 1.1 8-3.98). Conclusions: The behavioral factors associated with the HIV epidemic among Bangkok's IDU are similar to t hose described elsewhere. The monthly incidence of 5% from February to September 1988 suggests extensive needle or injection equipment shari ng networks among IDU in Bangkok. Additionally, the pattern of HIV-pos itivity by detoxification clinic over time in early 1988, and then in September 1988 is consistent with a relationship to the prison amnesty of early December 1987. Shortly after that date, an undisclosed numbe r of former IDU, a substantial number of whom were still injecting, an d may have become HIV-positive while in custody, returned to resume in jecting within existing drug-using networks throughout Bangkok and els ewhere in Thailand.