A prospective study of pharyngeal gonorrhoea and inconsistent condom use for oral sex among female brothel-based sex workers in Singapore.

Oral sex among female sex workers in Singapore has risen sharply from 27.1% in 1992 to 81.7% in 1997. A prospective cohort study was carried out on 724 female brothel-based sex workers who practised oral sex, to determine the risk of contracting pharyngeal gonorrhoea through inconsistent condom use. The prevalence of consistent condom use for oral sex was 70.4% compared to 96.8% for vaginal sex. One hundred and twenty-nine (17.8%) were lost to follow up because they quit prostitution. The other 595 sex workers were followed up for a maximum period of 6 months. Thirty-eight (5.2%) sex workers contracted pharyngeal gonorrhoea compared to 2.5% who contracted cervical gonorrhoea. Sex workers with inconsistent condom use for oral sex were 17.1 times (95% CI: 8.0-36.5) more likely than consistent condom users to develop pharyngeal gonorrhoea, after controlling for ethnic group, class and number of clients. STD control programmes for sex workers should place stress on consistent condom use for oral sex.