Objective: To determine whether HIV and sexually transmitted disease (STD) incidence rates among young men in northern Thailand have declined since the establishment of the '100% Condom Program', and to prospectively document changes in the association between behavioral risk factors and incident HIV and STD infections.
Setting: Thirteen military bases in northern Thailand.
Methods: Serial prospective cohorts of 19-23-year-old male conscripts (n = 4086) inducted into military service from six northern Thai provinces between 1991 and 1993 were followed at 6-month intervals for incident HIV and STD through May 1995. HIV incidence was determined by serology, and incident STD were reported by conscripts as diagnosed by health-care providers.
Results: HIV incidence declined from a rate of 2.48 per 100 person-years during 1991-1993 to 0.55 per 100 person-years during 1993-1995. STD incidence showed an even greater decline, with a 10-fold decrease from 1991-1993 to 1993-1995. Behavioral risk factors for incident STD infections included a history of prior STD and sex with girlfriends and sex workers. Inconsistent condom use remained a strong predictor of incident STD among brothel visitors. Other previously-reported risk factors in 1991-1993 such as illicit drug use, frequency and cost of brothel visits, and low socioeconomic status were not associated with incident STD or HIV in 1993-1995.
Conclusions: Although several studies have recently reported decreased prevalence of HIV and STD infections in Thailand, these data demonstrate that a dramatic decrease in the incidence rates of STD, including HIV infection, has occurred among young men in military service in northern Thailand. The Thai AIDS prevention and control program might be implemented by other countries experiencing major epidemics of heterosexually transmitted HIV infections. Similar prevention programs targeted at other populations in Thailand and elsewhere in Asia are needed to decrease the spread of the HIV epidemic.