Prevalence of genital and oropharyngeal chlamydia and gonorrhoea among female sex workers in Melbourne, Australia, 2015-2017: need for oropharyngeal testing

Objective The Victorian legislation requires sex workers to have quarterly screening for genital chlamydia and gonorrhoea, but screening for oropharyngeal infection is not mandatory in Victoria, Australia. In 2017, oropharyngeal screening for gonorrhoea and chlamydia was added as part of the routine quarterly screening for sex workers attending the Melbourne Sexual Health Centre (MSHC). The aim of this study was to examine the prevalence of oropharyngeal gonorrhoea and chlamydia among female sex workers (FSW). Methods We included females who (1) self-identified as sex workers or were attended MSHC for a sex work certificate and (2) had tested for any STI or HIV, between March 2015 and December 2017. The prevalence of HIV, syphilis, chlamydia and gonorrhoea was calculated. Results There were 8538 FSW consultations among 2780 individuals during the study period. There was a twofold increase in genital gonorrhoea (from 0.5% (95% CI 0.3% to 0.9%) to 1.1% (95% CI 0.8% to 1.5%); p(trend)=0.047) and a 1.5-fold increase in genital chlamydia (from 2.2% (95% CI 1.6% to 2.8%) to 3.2% (95% CI 2.6% to 3.8%); p(trend)=0.031) during the period. Overall, the prevalence of HIV (0.2% (95% CI 0.1% to 0.3%)) and syphilis (0.1% (95% CI 0.0% to 0.2%)) remained low and did not change over time. In 2017, the prevalence of oropharyngeal gonorrhoea was 2.0% (95% CI 1.6% to 2.6%) and oropharyngeal chlamydia was 2.1% (95% CI 1.6% to 2.7%). Among FSW who were tested positive for gonorrhoea and chlamydia, 55% (n=41) and 34% (n=45) only tested positive in the oropharynx but not genital for gonorrhoea and chlamydia, respectively. Conclusion The prevalence of oropharyngeal gonorrhoea and chlamydia is similar to the prevalence at genital sites and is often independent of genital infection. It is important to test the oropharynx and genital site for chlamydia and gonorrhoea among FSW.