Objective: To evaluate trends in HIV-1 seroprevalence in Thailand.
Design: HIV-1 serosurvey of successive cohorts of young Thai men entering service with the Royal Thai Army (RTA) between November 1989 and November 1994.
Methods: In November 1989, the RTA Medical Department began routine HIV-1-antibody screening of men who were selected by lottery for conscription. Between November 1989 and November 1994, 311,108 young men were screened at induction. Demographic data were collected between November 1991 and May 1993 and again in November 1994.
Results: The seroprevalence of HIV-1 among conscripts nationwide increased rapidly from 0.5% in 1989 to 3.5% in 1992 and reached 3.7% in 1993. In 1994, the overall prevalence decreased to 3.0%. The decrease was greatest in the upper North (from 12.4% in 1992 to 7.9% in 1994), where the prevalence has been the highest. However, decreases were observed in men from all regions of residence in the country, from both rural and urban areas, and at all educational levels.
Conclusions: The decline in prevalence suggests declining incidence and that HIV control programs in Thailand are having an impact on the HIV epidemic.
PIP: Since 1989, the Royal Thai Army has screened new conscripts for human immunodeficiency virus (HIV)-1 infection. An analysis of HIV test results for the 311,108 young men entering the Army between November 1989 and November 1994 indicates that the Thailand Government's acquired immunodeficiency syndrome (AIDS) prevention program has had a positive impact on high-risk behaviors. The HIV seroprevalence increased from 0.5% in 1989 to 3.5% in 1992 and 3.7% in 1993, but then fell to 3.0% in 1994. The prevalence in the North--the region with the highest rate--peaked at 7.5% in 1992, then declined to 5.1% in 1994. This pattern of decline was observed in all regions of residence and at all educational levels. The only exception was a slight increase (from 4.1% in 1992 to 5.0% in 1994) in seroprevalence among the 4.2% of conscripts aged 22-29 years. Condom use, less frequent visits to commercial sex workers, and decreasing rates of sexually transmitted diseases are assumed to be the factors contributing to the decline in HIV infection.