BRIDGE POPULATIONS IN THE SPREAD OF HIV AIDS IN THAILAND/

Objective: To determine the extent to which men provide a bridge popul ation between, commercial sex workers (CSW) and the general female pop ulation in Thailand. Design: Sexual network and serological data were collected from a systematic quota sample of low income men and trucker s during 1992 in three Thailand provinces. Completed sample size was 1 075 men aged 17-45 years and 330 truckers. Methods: Sexual network inf ormation was used to identify those men who have sex with both female CSW and non-CSW partners (the 'bridge population'). A new method was u sed for calculating the partner acquisition rate and to establish the potential number of women exposed to HIV via inconsistent condom use a mong the bridge population. Results: Approximately 17% of men and 25% of truckers can be included in the bridge population. These men are mo re likely to be HIV-positive and to have had at least one other sexual ly transmitted infection in the past year (odds ratio, 2.2 and 3.4, re spectively). Consistent condom use with CSW is less than 30%, and is l ess than 1% with non-CSW partners. As a result, 30 women in the genera l population were potentially exposed to HIV per 100 sexually active m en in the last year: nine women each additional year. Younger men and truckers expose almost twice as many women to HIV; more female peers t han wives are exposed.Conclusion: Bridge populations may be as importa nt as 'core groups' for the spread of HIV into the general Thai popula tion. Young men and women are strategic intervention targets because t hey have more partners, are more likely to be in bridging networks, an d are more receptive to condom use.