title: The Imaramagambo Onchocerciasis Focus in Southwestern Uganda: Interruption of Transmission After Disappearance of the Vector Simulium neavei and Its Associated Freshwater Crabs.
abstract: It was not until early 1990s that, when the Imaramagambo focus of southwest Uganda was mapped, mass treatment with a single annual dose of ivermectin for onchocerciaisis control commenced. However, comprehensive investigations on its transmission were launched after a nationwide policy for onchocerciasis elimination in 2007. Entomological surveys throughout the focus from 2007 to 2015 have yielded few or no freshwater crabs (Potamonautes aloysiisabaudiae), which serve as the obligate phoretic host of the larvae and pupae of the vector Simulium neavei No S. neavei flies have been observed or collected since 2007. Skin snips (microscopy) from 294 individuals in 2008 were negative for skin microfilariae, and of the 462 persons analyzed by polymerase chain reaction skin snip poolscreen in 2009, only five (1.08%) persons were indicated as infected with onchocerciasis. All five of the positive persons were at least 40 years old. Serosurvey results showed negative exposure among 3,332 children in 2012 and 3,108 children in 2015. Both were within the upper bound of the 95% confidence interval of the prevalence estimate of 0.06%, which confirmed the elimination of onchocerciasis. Treatment coverage in Imaramagambo was generally poor, and transmission interruption of onchocerciasis could not be attributed solely to annual mass treatment with ivermectin. There was sufficient evidence to believe that the possible disappearance of the S. neavei flies, presumed to have been the main vector, may have hastened the demise of onchocerciasis in this focus.
authors.affiliation: Health Programs, The Carter Center, Atlanta, Georgia.
authors.forename: Moses N
authors.initials: MN
authors.lastname: Katabarwa
authors.affiliation: Health Services, Kabarole District, Fort Portal, Uganda.
authors.forename: James
authors.initials: J
authors.lastname: Katamanywa
authors.affiliation: Vector Control Division, Ministry of Health, Kampala, Uganda.
authors.forename: Thomson
authors.initials: T
authors.lastname: Lakwo
authors.affiliation: Health Programs, The Carter Center, Kampala, Uganda.
authors.forename: Peace
authors.initials: P
authors.lastname: Habomugisha
authors.affiliation: Health Programs, The Carter Center, Kampala, Uganda.
authors.forename: Edson
authors.initials: E
authors.lastname: Byamukama
authors.affiliation: Vector Control Division, Ministry of Health, Kampala, Uganda.
authors.forename: David
authors.initials: D
authors.lastname: Oguttu
authors.affiliation: Vector Control Division, Ministry of Health, Kampala, Uganda.
authors.forename: Christine
authors.initials: C
authors.lastname: Nahabwe
authors.affiliation: Vector Control Division, Ministry of Health, Kampala, Uganda.
authors.forename: Monica
authors.initials: M
authors.lastname: Ngabirano
authors.affiliation: Health Services, Kabarole District, Fort Portal, Uganda.
authors.forename: Ephraim
authors.initials: E
authors.lastname: Tukesiga
authors.affiliation: Health Programs, The Carter Center, Kampala, Uganda.
authors.forename: Annet
authors.initials: A
authors.lastname: Khainza
authors.affiliation: Vector Control Division, Ministry of Health, Kampala, Uganda.
authors.forename: Edridah
authors.initials: E
authors.lastname: Tukahebwa
authors.affiliation: University of South Florida, Global Health, Tampa, Florida.
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Unnasch
authors.affiliation: Health Programs, The Carter Center, Atlanta, Georgia.
authors.forename: Frank O
authors.initials: FO
authors.lastname: Richards
authors.affiliation: Tropical Medicine Department, Bernhard Nocht Institute of Tropical Medicine, Hamburg, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Garms
mesh_terms: D000328:Adult; D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use; D003386:Brachyura / Q000469:parasitology; D060740:Disease Eradication; D062665:Epidemiological Monitoring; D005618:Fresh Water / Q000469:parasitology; D006801:Humans; D015994:Incidence; D007303:Insect Vectors / Q000469:parasitology; D007559:Ivermectin / Q000627:therapeutic use; D007814:Larva / Q000472:pathogenicity* / Q000502:physiology; D017181:Onchocerca volvulus / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D009855:Onchocerciasis / Q000175:diagnosis / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission*; D012843:Simuliidae / Q000469:parasitology; D014454:Uganda / Q000453:epidemiology
chemical_list: D000871:Anthelmintics; D007559:Ivermectin