Background An HIV preventive intervention aimed at female sex workers (FSW) and involving structural interventions, condom promotion and care for sexually transmitted infections (STI) is ongoing in Benin since 1993 [antiretroviral treatment (ART) available since 2005]. No routine surveillance of Neisseria gonorrhoeae (NG) resistance is carried out in Benin and, despite evidence of emerging ciprofloxacin resistance in surrounding countries, this antibiotic remained the recommended treatment till 2015. We estimated time trends in HIV/STI prevalence among FSW from 1993 to 2015.

Methods 8 integrated biological and behavioural surveys were conducted among FSW using cluster sampling procedures. HIV antibodies were detected on serum or dried blood spots using standard assays. Cervical (1993–99) or self-administered vaginal swabs (2002–15) were tested for NG and Chlamydia trachomatis (CT) using nucleic acid amplification tests. Time trend analysis controlled for potential socio-demographic confounders using log-binomial regression. HIV incidence data were available from 4 FSW cohort studies (1997–2000, 2005–07, 2009–12 and 2014–16).

Results HIV prevalence declined from 53.3% in 1993 to 49.4% in 1996, 40.7% in 1999, 46.5% in 2002, 30.1% in 2005, 26.8% in 2008, 20.5% in 2012 and 15.8% in 2015 (p<0.0001). During the same period, condom use with all clients in the last month increased from 13.9% in 1993 to 77.1% (p<0.0001) in 2015 (93% at last sex with a client in 2015). HIV incidence declined steadily, from 9.6 per 100 person-years in the 1997–2000 period to 5.9 in the 2005–07 period, 1.4 in the 2009–12 period and 0.9 per 100 person-years in the 2014–16 period. Following a sharp decline during the 1993–2005 period, from 43.2% in 1993 to 30.7% in 1996, 23.7% in 1999, 20.4% in 2002 and 3.4% in 2005 (p<0.0001), NG increased progressively to 6.2% in 2008, 6.8% in 2012 and 8.4% in 2015 (p<0.0001). CT also declined from 9.4% to 5.4% (1993–2005), but then stabilised at 4%–6%.

Conclusion Our results suggest a significant impact of this intervention aimed at FSW in Benin, where HIV prevalence in the general population is stable at 1.1% since 2006, despite increased survival due to ART scale-up (current ART coverage >50%). However, NG has steadily increased in the last decade likely due to inadequate treatment policies. Setting up NG resistance surveillance is of paramount importance in African countries, most of them not currently having such programs on a regular basis.

Support: Different sources of funding contributed to all these studies. They include the Canadian Institutes of Health Research, the Canadian International Development Agency, UNAIDS, the Contraceptive Research and Development Program, the World Bank, the Global Fund to Fight AIDS, Tuberculosis and Malaria and the Bill and Melinda Gates Foundation