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. 2014 Jun;90(6):1159-66.
doi: 10.4269/ajtmh.13-0501. Epub 2014 Mar 31.

Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon focus of Eastern Uganda has been interrupted

Moses Katabarwa  1 , Tom Lakwo  2 , Peace Habomugisha  2 , Stella Agunyo  2 , Edson Byamukama  2 , David Oguttu  2 , Richard Ndyomugyenyi  2 , Ephraim Tukesiga  2 , Galex Orukan Ochieng  2 , Francis Abwaimo  2 , Ambrose Onapa  2 , Dennis W K Lwamafa  2 , Frank Walsh  2 , Thomas R Unnasch  2 , Frank O Richards  2
Affiliations

Transmission of Onchocerca volvulus by Simulium neavei in Mount Elgon focus of Eastern Uganda has been interrupted

Moses Katabarwa et al. Am J Trop Med Hyg. 2014 Jun.

Abstract

The study determined that Simulium neavei-transmitted onchocerciasis in Mount Elgon onchocerciasis focus had been interrupted. Annual mass treatment with ivermectin changed to two times per year along with vector elimination in 2007. Then, baseline microfilaria (mf) prevalence data of 1994 in five sentinel communities were compared with follow-up data in 2005 and 2011. Blood spots from 3,051 children obtained in 2009 were analyzed for Onchocerca volvulus immunoglobulin G4 antibodies. Fresh water crab host captures and blackflies collected indicated their infestation with larval stages of S. neavei and presence or absence of the vector, respectively. Mf rates dropped from 62.2% to 0.5%, and 1 (0.03%) of 3,051 children was positive for O. volvulus antibodies. Crab infestation dropped from 41.9% in 2007 to 0%, and S. neavei biting reduced to zero. Both remained zero for the next 3 years, confirming interruption of onchocerciasis transmission, and interventions were halted.

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Figures

Figure 1.
Figure 1.
Map of Mount Elgon onchocerciasis focus of eastern Uganda.
Figure 2.
Figure 2.
Gauging and dosing points as well as fly-catching sites on river systems where S. neavei breeds in Mount Elgon focus.
Figure 3.
Figure 3.
History of mass treatment with ivermectin from 1994 to 2011 in Mount Elgon onchocerciasis focus in Uganda.
Figure 4.
Figure 4.
History of percent treatment coverage with ivermectin annually from 1994 to 2005 (UTG) and two times per year (UTG2) from 2006 to 2011 in Mount Elgon onchocerciasis focus in Uganda.
Figure 5.
Figure 5.
Trend of crab infestation from April of 2007 to September of 2011.
Figure 6.
Figure 6.
Trend of S. neavei adult fly catches from April of 2007 to June of 2011.
See this image and copyright information in PMC

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