We compared the impact of three rounds of annual and five rounds of semiannual mass drug administration (MDA) with albendazole plus ivermectin on helminthic infections in Liberia. Repeated annual cross-sectional community surveys were conducted between 2013 and 2019 in individuals of 5 years and older. Primary outcome was the change of infection prevalence estimates from baseline to month 36 (12 months after the last treatment). After three rounds of annual MDA, Wuchereria bancrofti circulating filarial antigen (CFA) and microfilaria (Mf) prevalence estimates decreased from 19.7% to 4.3% and from 8.6% to 0%, respectively; after semiannual MDA, CFA and Mf prevalences decreased from 37.8% to 16.8% and 17.9% to 1%, respectively. Mixed effects logistic regression models indicated that the odds of having Mf decreased by 97% (P < 0.001) at month 36 (similar odds for annual and semiannual MDA zones). A parallel analysis showed that the odds of CFA were reduced by 83% and 69% at 36 months in the annual and semiannual treatment zones, respectively (P < 0.001). Onchocerca volvulus Mf prevalence decreased slightly after multiple MDA rounds in both treatment zones. Reductions in hookworm and Trichuris trichiura prevalences and intensities were slightly greater in the annual treatment zone. Ascaris lumbricoides prevalence rates were relatively unchanged, although infection intensities decreased sharply throughout. Results show that annual and semiannual MDA were equally effective for reducing LF and soil-transmitted helminth infection parameters over a 3-year period, and reductions recorded at month 36 were sustained by routine annual MDA through month 72.
Address correspondence to Peter U. Fischer, Division of Biostatistics, Washington University School of Medicine, St. Louis, MO. E-mail: firstname.lastname@example.org
Financial support: This project was funded by grant GH5342 from the Bill & Melinda Gates Foundation to the DOLF Project (https://dolfproject.wustl.edu/). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The findings and conclusions contained within are those of the authors and do not necessarily reflect positions or policies of the Bill & Melinda Gates Foundation.
Disclaimer: The filarial antigen test used in this study uses reagents licensed from Barnes-Jewish Hospital, an affiliation of G. J. W. All royalties from sales of these tests go to the Foundation for Barnes-Jewish Hospital (https://www.foundationbarnesjewish.org/), a registered not-for-profit organization.
Authors’ addresses: Obiora A. Eneanya, Gary J. Weil, and Peter U. Fischer, Infectious Diseases Division, Department of Medicine, Washington University School of Medicine, St. Louis, MO, E-mails: email@example.com, firstname.lastname@example.org, and email@example.com. Charles W. Goss, Division of Biostatistics, Washington University School of Medicine, St. Louis, MO, E-mail: firstname.lastname@example.org. Lincoln Gankpala and Fatorma K. Bolay (deceased), Division of Public Health and Medical Research, National Public Health Institute of Liberia, Charlesville, Republic of Liberia, E-mail: email@example.com.