Semi-annual and annual mass drug administration of diethylcarbamazine and albendazole are equally effective regimens for eliminating lymphatic filariasis in Papua New Guinea

Annual mass drug administration (MDA) is currently recommended for the local elimination of lymphatic filariasis (LF). Modeling studies of LF transmission suggest that conducting MDA twice a year could accelerate LF elimination. To test this idea, we compared the effects of 3 rounds of yearly MDA and 5 rounds of semiannual MDA using diethylcarbamazine with albendazole on LF infection measures in Papua New Guinea (PNG) across 2 treatment areas with high LF prevalence. From 2013 to 2018, we conducted 4 annual community surveys at 4 sentinel sites in each treatment area. We sampled 2,854 people at the start and 2,746, 2,339, and 2,569 people at 13, 27, and 40 months, respectively, with a similar number of participants in each area. Yearly MDA reduced microfilariae (Mf) prevalence from 24.0% at baseline (95% confidence interval [CI] 22.9-26.1%) to zero (CI, 0-0.4%) at 40 months. Similarly, semiannual MDA lowered Mf prevalence from 23.3% (CI, 21.4-25.4%) to 0.3% (CI, 0.1-0.7%). The circulating filarial antigen (CFA) prevalence decreased from 46.4% at baseline (CI, 43.5-49.3%) to 29.5% (CI, 26.9-32.3%) after 40 months with yearly treatment and from 53.4% (CI, 51.0-55.9%) to 35.2% (CI, 32.7-37.8%) with semiannual MDA. Using a generalized estimating equation model that accounted for age, sex, bednet use, and sentinel site, we found no significant difference in the effectiveness of the two treatment approaches (p = 0.845 for Mf and p = 0.332 for CFA). Therefore, annual and semiannual MDA were equally effective in reducing LF prevalence in this high-endemic setting.