Background Population mobility has long been associated with frequency and variety of sexually transmitted infections including HIV. People's mobility tends to disrupt their traditional social constraints and control of sexual behaviour by giving them opportunity, isolation and the desire for unique experiences. Fishermen being one of the highly mobile populations, we sought to evaluated the extent to their mobility predicts their involvement in high risk sexual behaviour.

Methods During a Phase I randomised double-blind placebo-controlled cross over trial evaluating the safety and acceptability of ethanol in emollient gel as a topical male microbicide, we collected data on fishermen's socio-economic and demographic characteristics, mobility patterns and sexual practices including extra-marital partnerships. We pre- and post-test counselled for STIs, obtained blood samples for HIV, HSV-2 and syphilis serologies and provided appropriate treatment and referrals. We analysed the data using descriptive statistics and then bivariate and multivariate logistic regression.

Results Of the 167 fishermen screened, over a half (52%) were mobile defined as travelling and spending at least one night away from home in the month preceding the study). Two-thirds (63%) had active extra-marital relationships with only 5% consistently using condoms in these sexual encounters. During travel, a quarter (24%) drank alcohol and a similar number (25%) had sex with a third (32%) reporting new casual sex partners. At bivariate level, those travelling in the month preceding the study were more likely to be HIV+ (OR 2.08; 95% CI 1.01 to 4.28), have an active extra-marital relationship (OR 3.69; 95% CI 1.57 to 8.68), and have multiple sex partners in the six month preceding the study (OR 2.04; 95% CI 1.06 to 3.95). Mobility among fishermen was independently associated with having an active extra-marital relationship (AOR 3.64; 95% CI 1.11 to 12.00).

Conclusion Mobile fishermen exhibit high risk sexual behaviour that include extra-marital sex and low condom use. This population is likely to benefit from STI/HIV prevention intervention.