The burden of skin disease and eye disease due to onchocerciasis in countries formerly under the african programme for onchocerciasis control mandate for 1990, 2020, and 2030

Natalie V.S. Vinkeles Melchers*, Wilma A. Stolk, WA (Welmoed) van Loon, Belén Pedrique, Roel Bakker, Michele E. Murdoch, Sake J. de Vlas, Luc E. Coffeng*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Background Onchocerciasis (“river blindness”) can cause severe morbidity, including vision loss and various skin manifestations, and is targeted for elimination using ivermectin mass drug administration (MDA). We calculated the number of people with Onchocerca volvulus infection and onchocercal skin and eye disease as well as disability-adjusted life years (DALYs) lost from 1990 through to 2030 in areas formerly covered by the African Programme for Onchocerciasis Control. Methods Per MDA implementation unit, we collated data on the pre-control distribution of microfilariae (mf) prevalence and the history of control. Next, we predicted trends in infection and morbidity over time using the ONCHOSIM simulation model. DALY estimates were calculated using disability weights from the Global Burden of Disease Study. Results In 1990, prior to MDA implementation, the total population at risk was 79.8 million with 26.0 million (32.5%) mf-positive individuals, of whom 17.5 million (21.9%) had some form of onchocercal skin or eye disease (2.5 million DALYs lost). By 2030, the total population was predicted to increase to 236.1 million, while the number of mf-positive cases (about 6.8 million, 2.9%), people with skin or eye morbidity (4.2 million, 1.8%), and DALYs lost (0.7 million) were predicted to decline. Conclusions MDA has had a remarkable impact on the onchocerciasis burden in countries previously under the APOC mandate. In the few countries where we predict continued transmission between now and 2030, intensified MDA could be combined with local vector control efforts, or the introduction of new drugs for mopping up residual cases of infection and morbidity.

Original languageEnglish
Article numbere0009604
JournalPLoS Neglected Tropical Diseases
Issue number7
Publication statusPublished - Jul 2021

Bibliographical note

Funding Information:
NVSVM, WAS, WvL, BP, and LEC received funding from the United States Agency for International Development (USAID, www.usaid. gov) through the Drugs for Neglected Diseases initiative (DNDi, (ref no. AID-OAAG14-00010). The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government. For its overall mission, DNDi receives support from UK aid, UK (; MOU 2013-2018 and MOU 2017-2021); M?decins sans Fronti?res (MSF,; MOU 2014-2018 and MOU 2019-2023); and the Swiss Agency for Development and Cooperation, Switzerland (SDC,; contract no. 81017718 and no. 81050394). WAS, SJdV, and LEC gratefully acknowledge funding of the NTD Modelling Consortium by the Bill & Melinda Gates Foundation (; grant OPP1184344). LEC further acknowledges funding from the Dutch Research Council (NWO,; grant 016. Veni.178.023). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.We would like to warmly thank Louise Burrows (DNDi) for editing the final draft of the manuscript. We would like to acknowledge WHO/AFRO for approving the use and publication of the data used in this manuscript. We are grateful to Hans Remme for helping in compiling pixel-level mf prevalence data and stratifying these pixels per APOC project over endemicity levels and coupling to population census data. In addition, we would like to thank Federica Giardina for their statistical advice in the programming of R during the initial modelling and analysis stage.

Publisher Copyright:
© 2021 Vinkeles Melchers et al.


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