Frequency and risk of HIV infection among men attending a clinic for STD in Chiang Mai, Thailand.

A prospective study was conducted in the Chiang Mai Sexually Transmitted Diseases Clinic to determine the frequency of HIV seroconversion among men following high risk sexual contacts and to establish risk factors for HIV infection. HIV antibodies were detected in 26 out of 150 men on the initial recruitment with a seroprevalence rate of 21%. Among 124 initial HIV negative subjects; 100, 77, 68, and 55 subjects were followed for 2, 4, 12, and 24 weeks, respectively. One subject had HIV seroconversion documented with the rate of 1.0% (1/100, 95% confidence interval [CI] = 0.03-5.4%). Logistic regression analysis found significantly independent associations of HIV prevalence with prostitute visits at least once a month (OR = 3.6, 95% CI = 1.2-10.9), and with cigarette smoking (OR = 3.5, 95% CI = 1.2-10.5). Intensive health education should be elucidated to decrease the high rate of HIV infection among this population.