An international team of researchers has found that intensive behavioral interventions in structured institutions, such as the military, can successfully reduce the risk of sexually transmitted diseases. To confront the growing heterosexual HIV epidemic in northern Thailand, the researchers designed, implemented and evaluated a preventive field trial carried out by the Royal Thai Army. Aimed at changing behavior at the individual, group and institutional levels, the intervention focused on reducing sexual risk by promoting consistent condom use, reducing alcohol consumption and brothel patronage, and improving sexual negotiation and condom skills. The study was published in the March issue of the Archives of Internal Medicine.

Didactic health education sessions conducted in previous years had done little to reduce STD and HIV infection rates among recruits; thus, the Thai military was motivated to use its command structure to mount an active intervention.

According to lead author David D. Celentano, a professor in the Department of Epidemiology in the School of Public Health, "The results of this study demonstrate the utility of conducting behavioral interventions to reduce STD and HIV risk at the institutional level. The highly structured nature of an organization can be useful in reinforcing messages, integrating the intervention across activities of daily life and taking advantage of naturally existing social networks."

Thai military companies with the same mission were assigned to intervention, diffusion and control groups. The diffusion and control groups did not participate in the intervention. By monitoring the diffusion group, which consisted of men stationed at the same base as the intervention participants, the researchers could determine whether the intervention spread, or diffused, beyond the participant group or whether sexual risk-taking behaviors filtered in from outside the group. Men in the control group were stationed at distant camps. The study population consisted of 450 men in the intervention group, 681 men in the diffusion group and 414 men in the control group.

Baseline HIV screening and risk-factor surveys were completed at the induction of conscripts--men drafted by lottery--in May and November 1993, and the men were followed semiannually through May 1995. The participants received HIV testing and risk-reduction counseling every six months, as well as extensive HIV prevention activities, including health education lectures and exercises, implemented over 15 months, from November 1993 through January 1995. To evaluate the efficacy of the intervention, the researchers conducted a statistical analysis of the number of new cases of STD and HIV infections among men in the intervention, diffusion and control groups.

The STD incidence rate declined sevenfold among men assigned to the intervention group. There was also a 50 percent decrease in the rate of new HIV cases, but this decline was not statistically significant. No diffusion of the intervention to the adjacent barracks was observed. The intervention was adopted by the Royal Thai Army for all conscripts.