Sexually transmitted infections (STIs) are a major public health problem globally, particularly in low and middle-income countries. In the Western Pacific region, including Nauru, STIs are highly prevalent. Syndromic management misses a high proportion of infections and screen-and-treat strategies are not currently feasible at scale in these settings. Mass drug administration (MDA), widely used for control of neglected tropical diseases, may provide an alternative approach to the population control of STIs.
We used a before-and-after study design to evaluate the impact of azithromycin MDA for trachoma control on STI prevalence in Nauru. The study enrolled 381 participants aged 18–29 years before MDA and 360 participants 6 months after MDA, with similar age distribution but a higher proportion of women post-MDA. Urine specimens were tested for Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium and Trichomonas vaginalis.
At baseline, C. trachomatis infection was present in 21.7% of participants followed by T. vaginalis and M. genitalium (21.2% and 10.9%, respectively), while N. gonorrhoeae was detected in 2.7% of participants. At 6 months after azithromycin MDA, prevalence declined for all STIs except T. vaginalis. Relative reductions were 35% (95% CI 9.7 to 52.8) for C. trachomatis, 67% (–15.2 to 91.1) for N. gonorrhoeae and 47% (10.7 to 68.2) for M. genitalium. Reductions in prevalence following MDA were greater in men than women but CIs overlapped.
This study provides the first evaluation among both men and women of changes in STI prevalence following azithromycin MDA in a high-prevalence general population. The potential role of this strategy in STI control needs further exploration.