Objectives: To determine risk factors for HIV-1 infection in young men
in northern Thailand, Methods: At enrollment into a prospective study
, data were collected from a self-administered questionnaire and serol
ogic testing on a cohort of 1115 young men selected by lottery for con
scription. Results: The overall HIV-1 infection rate was 6.9%; however
, the rate was 15.3% among the 387 (34.7%) men who had been living in
the upper north subregion of Thailand compared with 2.5% for the remai
ning 728 men (P < 0.001). A history of sex with female prostitutes was
reported by 74.7% of men and increased frequency of this type of sex
was highly associated with HIV-1 infection and a history of sexually t
ransmitted disease (STD) symptoms (chi2 for trend, P < 0.001). In stra
tified and multivariate analyses, however, history of STD symptoms, re
ported by 42.5% of the cohort, was most strongly associated with HIV-1
infection. Only 42.8% of men who reported sex with prostitutes had us
ed condoms more than half the time. Conclusions: Young men in the gene
ral population in northern Thailand are at high risk for HIV-1 infecti
on via sex with female prostitutes; STD are highly associated with HIV
-1 infection. Increasing condom use and controlling STD should be imme
diate goals of HIV control programs.