Integrated mass drug administration for yaws eradication: evidence from a comparative observational study in Papua...

Yaws is a chronic infectious disease that disproportionately affects under-reached communities. In 2023, Papua New Guinea (PNG) reported 100 165 suspected yaws cases, accounting for 45% of cases reported worldwide. The WHO targets yaws eradication by 2030, primarily through mass drug administration (MDA) of azithromycin. This study evaluates the impact of an integrated MDA programme in PNG and reviews global evidence on optimal MDA strategies through a network meta-analysis (NMA).

A comparative observational study was undertaken analysing outpatient department (OPD) attendances between West New Britain province (WNB; intervention) and New Ireland province (NIP; comparator) from November 2023 to August 2024. The intervention in WNB involved a single-round, integrated four-drug MDA provided in December 2023, comprising azithromycin, ivermectin, diethylcarbamazine and albendazole. Temporal trends in OPD attendances were analysed using negative binomial regression. A Bayesian NMA of six studies identified through a systematic review compared the effectiveness of azithromycin-based regimens for yaws eradication.

Between Q3 2023 and Q1 2024, yaws-related OPD attendances in WNB declined significantly, with a 41% (p<0.0001) reduction relative to the comparator province (NIP). This reduction was sustained for at least 6 months following MDA. Over the same period, a 33% decline in total skin-related outpatient attendances was observed. In the NMA, three rounds of azithromycin MDA were associated with lower odds of active yaws at follow-up than observation (OR 0.04, 95% CrI 0.005 to 0.24) and had the highest probability of being ranked most effective. Single-round azithromycin MDA was also associated with reduced odds of active yaws at follow-up (OR 0.15, 95% CrI 0.05 to 0.45).

In a high-burden setting, a single round of integrated MDA was associated with substantial early reductions in yaws burden. Multi-round azithromycin strategies, particularly three-round regimens, were associated with larger and more sustained reductions in community prevalence. These findings inform considerations for yaws control efforts in settings with persistent transmission.