Abstract
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.