The epidemiology of HIV and syphilis among male commercial sex workers in northern Thailand

Objective: To examine the prevalence and incidence of HIV and syphilis, and risk behaviors for these infections, among 1172 male commercial sex workers (CSW) followed prospectively from 1989 to 1994 in Chiang Mai, northern Thailand. Methods: Twice yearly visits were conducted by the Thai Ministry of Public Health at all cooperating gay bars and clubs (17 sites) in Chiang Mai City as part of a national HIV sentinel surveillance. Men and boys who agreed were followed prospectively. Sentinel visits included an interview, HIV pre-test counseling, HIV and syphilis serology, condom distribution, and referral for post-test counseling. Participation was voluntary, confidential, and individual HIV results were available only to participating subjects. A total of 219 CSW were seen at least twice, allowing for incidence estimates based on 100 person-years (PY). Results: Median age of male CSW was 20 years. Median time of work as a CSW was 4 months. Most men (57.6%) described themselves as heterosexual. Median number of clients was 2.5 per week, and reported condom use with clients was low: 42% reported inconsistent or no condom use, while 58% reported always using condoms. Reactive Venereal Disease Research Laboratory results were 7.6%, overall, but showed a declining trend. HIV prevalence was 1.4% in June 1989, 13.9% in June 1990, and 20.1% in December 1993, and showed a significant increasing trend. There were 27 incident HIV infections in 227.3 PY of observation, for an overall incidence during the 4.5-year period of 11.9 per 100 PY (95% confidence interval, 7.42-16.38). Conclusion: Male CSW in northern Thailand are at high risk for HIV despite current prevention efforts. The majority are heterosexual, which may be an important epidemiologic link in the spread of HIV between male CSW users and heterosexual women in Thailand.