• 1.

    Boatin B, 2008. The onchocerciasis control programme in west Africa (OCP). Ann Trop Med Parasitol 102 (Suppl 1): 1317.

  • 2.

    Stolk WA, Walker M, Coffeng LE, Basanez MG, de Vlas SJ, 2015. Required duration of mass ivermectin treatment for onchocerciasis elimination in Africa: a comparative modelling analysis. Parasit Vect 8: 552.

    • Search Google Scholar
    • Export Citation
  • 3.

    World Health Organization, 2020. Ending the Neglect to Attain the Sustainable Development Goals: A Road Map for Neglected Tropical Diseases 2021–2030. Geneva, Switzerland: WHO. Available at: https://creativecommons.org/licenses/by-nc-sa/3.0/igo. Accessed July 30, 2020.

    • Search Google Scholar
    • Export Citation
  • 4.

    World Health Organization, 2019. The World Health Organization 2030 goals for onchocerciasis: insights and perspectives from mathematical modeling: NTD Modelling Consortium Onchocerciasis Group. Gates Open Res 3: 1545.

    • Search Google Scholar
    • Export Citation
  • 5.

    Verver S 2018. How can onchocerciasis elimination in Africa be accelerated? Modeling the impact of increased ivermectin treatment frequency and complementary vector control. Clin Infect Dis 66: S267S274.

    • Search Google Scholar
    • Export Citation
  • 6.

    Smith ME 2019. Accelerating river blindness elimination by supplementing MDA with a vegetation “slash and clear” vector control strategy: a data-driven modeling analysis. Sci Rep 9: 15274.

    • Search Google Scholar
    • Export Citation
  • 7.

    Kruger A, Nurmi V, Yocha J, Kipp W, Rubaale T, Garms R, 1999. The Simulium damnosum complex in western Uganda and its role as a vector of Onchocerca volvulus. Trop Med Int Health 4: 819826.

    • Search Google Scholar
    • Export Citation
  • 8.

    Dunbar RW, 1966. Four sibling species included in Simulium damnosum Theobald (Diptera: Simuliidae) from Uganda. Nature 209: 597599.

  • 9.

    Crosskey RW, Howard TM, 1996. A New Taxonomic and Geographic Inventory of World Blackflies (Diptera: Simuliidae). London, United Kingdom: Natural History Museum.

    • Search Google Scholar
    • Export Citation
  • 10.

    Katabarwa M 2012. Transmission of onchocerciasis in Wadelai focus of northwestern Uganda has been interrupted and the disease eliminated. J Parasitol Res 2012: 748540.

    • Search Google Scholar
    • Export Citation
  • 11.

    Katabarwa M 2014. Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon focus of eastern Uganda has been interrupted. Am J Trop Med Hyg 90: 11591166.

    • Search Google Scholar
    • Export Citation
  • 12.

    Lakwo TL 2015. Successful interruption of the transmission of Onchocerca volvulus in Mpamba-Nkusi focus, Kibaale district, mid-western Uganda. East Afr Med J 92: 401407.

    • Search Google Scholar
    • Export Citation
  • 13.

    Lakwo T 2017. Interruption of the transmission of Onchocerca volvulus in the Kashoya-Kitomi focus, western Uganda by long-term ivermectin treatment and elimination of the vector Simulium neavei by larviciding. Acta Trop 167: 128136.

    • Search Google Scholar
    • Export Citation
  • 14.

    Luroni LT 2017. The interruption of Onchocerca volvulus and Wuchereria bancrofti transmission by integrated chemotherapy in the Obongi focus, north western Uganda. PLoS One 12: e0189306.

    • Search Google Scholar
    • Export Citation
  • 15.

    Katabarwa M 2020. Elimination of Simulium neavei transmitted onchocerciasis in Wambabya-Rwamarongo focus of western Uganda Am J Trop Med Hyg 103: 11351142.

    • Search Google Scholar
    • Export Citation
  • 16.

    Katabarwa M 2020. The Galabat-Metema cross-border onchocerciasis focus: the first coordinated interruption of onchocerciasis transmission in Africa. PLoS Negl Trop Dis 14: e0007830.

    • Search Google Scholar
    • Export Citation
  • 17.

    Jacob BG, Loum D, Lakwo TL, Katholi CR, Habomugisha P, Byamukama E, Tukahebwa E, Cupp EW, Unnasch TR, 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.

    • Search Google Scholar
    • Export Citation
  • 18.

    Uganda National Bureau of Statistics, 2020. National Population and Housing Census- Uganda National Bureau of Statistics (UBOS), 2014. Available at: http://unstats.un.org/unsd/.../sources/census/../Uganda/UGA-2016-05-23.pdf. Accessed August 1, 2020.

    • Search Google Scholar
    • Export Citation
  • 19.

    Langlands BW, Jackson RT, Mbakyenga SK, 1974. Soil Productivity and Land Availability Studies for Uganda. Kampala, Uganda: Department of Geography, Makerere University, 5569.

    • Search Google Scholar
    • Export Citation
  • 20.

    Ministry of Water and The Environment, 2020. Upper Nile Water Management Zone (UNWMZ): Water Resources Development and Management Strategy and Action Plan. Available at: https://www.mwe.go.ug/sites/default/files/library/UNWMZ%20Strategy%20%26%20Action%20Plan.pdf. Accessed September 21, 2020.

    • Search Google Scholar
    • Export Citation
  • 21.

    Jacob BG, Novak RJ, Toe L, Sanfo M, Griffith DA, Lakwo TL, Habomugisha P, Katabarwa MN, Unnasch TR, 2013. Validation of a remote sensing model to identify Simulium damnosum s.l. breeding sites in sub-Saharan Africa. PLoS Negl Trop Dis 7: e2342.

    • Search Google Scholar
    • Export Citation
  • 22.

    Rodriguez-Perez MA, Lutzow-Steiner MA, Segura-Cabrera A, Lizarazo-Ortega C, Dominguez-Vazquez A, Sauerbrey M, Richards F Jr., Unnasch TR, Hassan HK, Hernandez-Hernandez R, 2008. Rapid suppression of Onchocerca volvulus transmission in two communities of the southern Chiapas focus, Mexico, achieved by quarterly treatments with Mectizan. Am J Trop Med Hyg 79: 239244.

    • Search Google Scholar
    • Export Citation
  • 23.

    Le Berre R, 1966. Contribution a l’etude biologique et ecologique de Simulium damnosum Theobald, 1903 Simuliid. Mem ORSTOM 17: 204.

  • 24.

    Duke BO, 1975. The differential dispersal of nulliparous and parous Simulium damnosum. Tropenmed Parasitol 26: 8897.

  • 25.

    Renz A, Wenk P, 1987. Studies on the dynamics of transmission of onchocerciasis in a Sudan-savanna area of north Cameroon I. Prevailing Simulium vectors, their biting rates and age-composition at different distances from their breeding sites. Ann Trop Med Parasitol 81: 215228.

    • Search Google Scholar
    • Export Citation
  • 26.

    Duerr HP, Eichner M, 2010. Epidemiology and control of onchocerciasis: the threshold biting rate of savannah onchocerciasis in Africa. Int J Parasitol 40: 641650.

    • Search Google Scholar
    • Export Citation
  • 27.

    Awadzi K 2004. An investigation of persistent microfilaridermias despite multiple treatments with ivermectin, in two onchocerciasis-endemic foci in Ghana. Ann Trop Med Parasitol 98: 231249.

    • Search Google Scholar
    • Export Citation
  • 28.

    Churcher TS, Pion SD, Osei-Atweneboana MY, Prichard RK, Awadzi K, Boussinesq M, Collins RC, Whitworth JA, Basanez MG, 2009. Identifying sub-optimal responses to ivermectin in the treatment of river blindness. Proc Natl Acad Sci U S A 106: 1671616721.

    • Search Google Scholar
    • Export Citation
  • 29.

    Osei-Atweneboana MY, Awadzi K, Attah SK, Boakye DA, Gyapong JO, Prichard RK, 2011. Phenotypic evidence of emerging ivermectin resistance in Onchocerca volvulus. PLoS Negl Trop Dis 5: e998.

    • Search Google Scholar
    • Export Citation
  • 30.

    Doyle SR 2017. Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity. PLoS Negl Trop Dis 11: e0005816.

    • Search Google Scholar
    • Export Citation
  • 31.

    Crosskey RW, 1981. A review of S. damnosum s. l. and human onchocerciasis in Nigeria, with special reference to geographical distribution and the development of a Nigerian national control campaign. Tropenmed Parasitol 32: 216.

    • Search Google Scholar
    • Export Citation
  • 32.

    Loum D, Cozart D, Lakwo T, Habomugisha P, Jacob B, Cupp EW, Unnasch TR, 2019. Optimization and evaluation of the Esperanza Window trap to reduce biting rates of Simulium damnosum sensu lato in northern Uganda. PLoS Negl Trop Dis 13: e0007558.

    • Search Google Scholar
    • Export Citation

 

 

 

 

Optimization of Slash and Clear Community-Directed Control of Simulium damnosum Sensu Stricto in Northern Uganda

View More View Less
  • 1 College of Public Health, University of South Florida, Tampa, Florida;
  • 2 Nwoya District Local Government, Nwoya, Uganda;
  • 3 The Carter Center, Uganda Office, Kampala, Uganda;
  • 4 Vector Control Division, Ministry of Health, Kampala, Uganda;
  • 5 Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida

ABSTRACT

Onchocerciasis, caused by infection with Onchocerca volvulus, has been targeted for elimination by 2030. Currently, onchocerciasis elimination programs rely primarily on mass distribution of ivermectin. However, ivermectin alone may not be sufficient to achieve elimination in some circumstances, and additional tools may be needed. Vector control has been used as a tool to control onchocerciasis, but vector control using insecticides is expensive and ecologically detrimental. Community-directed removal of the trailing vegetation black fly larval attachment sites (slash and clear) has been shown to dramatically reduce vector biting densities. Here, we report studies to optimize the slash and clear process. Conducting slash and clear interventions at Simulium damnosum sensu stricto breeding sites located within 2 km of afflicted communities resulted in a 95% reduction in vector biting. Extending slash and clear further than 2 km resulted in no further decrease. A single intervention conducted at the first half of the rainy season resulted in a 97% reduction in biting rate, whereas an intervention conducted at the end of the rainy season resulted in a 94% reduction. Vector numbers in any of the intervention villages did not fully recover by the start of the following rainy season. These results suggest that slash and clear may offer an inexpensive and effective way to augment ivermectin distribution in the effort to eliminate onchocerciasis in Africa.

Author Notes

Address correspondence to Thomas R. Unnasch, Global Health Infectious Disease Program, 3720 Spectrum Blvd., Suite 304 Tampa, FL 33612. E-mail: tunnasch@usf.edu

Financial support: This study was supported by a grant from the U.S. National Institute of Allergy and Infectious Diseases to T. L. and T. R. U. (Award #1 R01 AI123245-01).

Authors’ addresses: Benjamin Jacob, College of Public Health, Global and Planetary Health, Tampa, FL, E-mail: bjacob1@usf.edu. Denis Loum, Health Department, Nwoya District Local Government, Gulu, Uganda, E-mail: loumdenis2@gmail.com. Denis Munu, Edson Byamukama, and Peace Habomugisha, The Carter Center Uganda, Kampala, Uganda, E-mails: denis.munu@gmail.com, edson.navs@gmail.com, and peace.habo@cartercenter.org. Thomson Lakwo, Vector Control Division, Ministry of Health, Kampala, Uganda, E-mail: tlakwo@gmail.com. Eddie W. Cupp, Center for Global Health Infectious Disease Research, Tampa, FL, E-mail: cuppedd@auburn.edu. Thomas R. Unnasch, Global Health Infectious Disease Program, Tampa, FL, E-mail: tunnasch@usf.edu.

Save