Onchocerciasis, or river blindness, is one of the recognized neglected tropical diseases of mankind. The disease is caused by the filarial parasite Onchocerca volvulus, which is spread by black flies (Simulium spp). In the 1980s, ivermectin was first shown to be a potent microfilaricide against O. volvulus. As a result, international programs were begun to either control or eliminate onchocerciasis, employing a strategy of mass drug administration (MDA) of ivermectin to afflicted communities. Long term MDA based programs have resulted in the elimination of onchocerciasis from some foci in Africa and almost all foci in Latin America. These successes have resulted in a change in focus from a goal of disease control of onchocerciasis to a goal of elimination, enshrined in the London Declaration on Neglected Tropical Diseases, which set a goal of eliminating onchocerciasis from Africa by 2020. Despite these successes, MDA alone will probably not be sufficient to interrupt transmission in many regions of Africa in time to meet the London Declaration goals, and may not be capable of interrupting transmission at all where vector densities are high. In such areas, it will be necessary to supplement MDA with other interventions. The experience of Uganda has demonstrated the power of utilizing a combination of vector control and ivermectin MDA, which has resulted in the interruption of transmission of O. volvulus in 9 of the country?s 17 foci in just 7 years. However, black fly control has traditionally relied upon insecticide treatment of vector breeding sites, an approach that is expensive and logistically difficult. Here we propose a different paradigm for the control of the black fly vectors of O. volvulus, that of involving the afflicted communities in this process. This project is an outgrowth of recent projects (1) to develop a black fly trap to replace human landing collections for entomological monitoring of O. volvulus transmission and, (2) to develop a remote sensing algorithm capable of predicting vector black fly breeding habitats. The first project resulted in the development of the Esperanza Window Trap (EWT), a platform constructed from locally available inexpensive materials, which equals or out performs a human landing team for the collection of vector species. The EWT can be successfully operated by local residents and has been shown to significantly reduce biting rates. In the second effort, we have conducted preliminary studies that demonstrate that enlisting local residents to remove trailing vegetation from detected vector breeding sites can reduce local biting rates by over 80%. The overall hypothesis that will be evaluated in this project through a combination of field experiments and mathematical modeling studies is that community directed vector control efforts using optimized traps, local reduction of breeding habitat or some combination of these will reduce vector biting rates to a point where O. volvulus may be eliminated by co-administration of MDA, even in areas where vector density is high.

Public Health Relevance

Onchocerciasis, or river blindness, is one of the neglected tropical diseases of mankind. Currently, the international community has set a goal of eliminating this scourge from the planet by 2020. However, almost all onchocerciasis elimination programs rely exclusively on mass distribution of ivermectin (MDA), and studies have shown that MDA will not be sufficient to meet the 2020 goal in most places, and may not be capable of achieving elimination when used alone in many foci in Africa. The goal of this project is to develop a community-based vector control program to supplement the use of ivermectin MDA, bringing the goal of onchocerciasis elimination within reach.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1)
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Costero-Saint Denis, Adriana
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University of South Florida
Other Health Professions
Schools of Public Health
United States
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Michael, Edwin; Smith, Morgan E; Katabarwa, Moses N et al. (2018) Substantiating freedom from parasitic infection by combining transmission model predictions with disease surveys. Nat Commun 9:4324
Jacob, Benjamin G; Loum, Denis; Lakwo, Thomson L et al. (2018) Community-directed vector control to supplement mass drug distribution for onchocerciasis elimination in the Madi mid-North focus of Northern Uganda. PLoS Negl Trop Dis 12:e0006702