Preventive intervention to reduce sexually transmitted infections - A field trial in the Royal Thai Army

Background: During 1991 through 1993, sexually transmitted infections among conscripts in the Royal Thai Army in the upper-northern provinces were com mon: human immunodeficiency virus (HIV) prevalence at induction was 12%, HI V incidence was 2.4% per year, and incidence of sexually transmitted diseas es was 17% per year. We evaluated a behavioral intervention to reduce incid ent sexually transmitted infections among conscripts inducted into the Thai Army in 1993. Methods: We developed a preventive intervention that addressed consistent c ondom use, reducing alcohol consumption and brothel patronage, and improvin g sexual negotiation and condom skills. Companies were assigned to 1 of 3 g roups matched on military mission: 450 men were in the intervention group, 681 were in barracks at the same base but did not receive the intervention (diffusion group), and 414 were in distant camps (controls). Baseline HIV s erological testing and behavioral interviews were con-ducted during basic t raining in 1993. The intervention was applied for 15 months, and men were f ollowed up at B-month intervals (with repeated HIV serological testing, sex ually transmitted disease assessments, and behavioral interviews) through M ay 1995. Results: Incident sexually transmitted diseases were 7 times less frequent among men assigned to the intervention than the combined controls (relative risk, 0.15, 95% confidence interval, 0.04-0.55), after adjusting for basel ine risk factors (P<.005). There was no diffusion of the intervention to ad jacent barracks. The intervention decreased incident HIV by 50% in the inte rvention group. Conclusion: Intensive interventions in structured institutions can successf ully reduce risk in settings confronting expanding heterosexual HIV epidemi cs.