Prevalence and intensity of Onchocerca volvulus infection and efficacy of ivermectin in endemic communities in Ghana: a two-phase epidemiological study

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dc.contributor.author Osei-Atweneboana, M.Y.
dc.contributor.author Eng, J.K.
dc.contributor.author Boakye, D.A.
dc.contributor.author Gyapong, J.O.
dc.contributor.author Prichard, R.K.
dc.date.accessioned 2013-09-27T11:42:22Z
dc.date.accessioned 2017-10-16T12:31:00Z
dc.date.available 2013-09-27T11:42:22Z
dc.date.available 2017-10-16T12:31:00Z
dc.date.issued 2007-06
dc.identifier.citation Osei-Atweneboana, M. Y., Eng, J. K., Boakye, D. A., Gyapong, J. O., & Prichard, R. K. (2007). Prevalence and intensity of onchocerca volvulus infection and efficacy of ivermectin in endemic communities in ghana: A two-phase epidemiological study. Lancet, 369(9578), 2021-2029. en_US
dc.identifier.issn 01406736
dc.identifier.uri http://197.255.68.203/handle/123456789/4389
dc.description.abstract Background: Ivermectin has been used for onchocerciasis control since 1987. Because of the long-term use of this drug and the development of resistance in other nematodes, we have assessed Onchocerca volvulus burdens, effectiveness of ivermectin as a microfilaricide, and its effect on adult female worm reproduction. Methods: For the first phase of the study, 2501 individuals in Ghana, from 19 endemic communities who had received six to 18 annual rounds of ivermectin and one ivermectin naive community, were assessed for microfilarial loads 7 days before the 2004 yearly ivermectin treatment, by means of skin snips, and 30 days after treatment to assess the ivermectin microfilaricidal action. For the second phase, skin snips were taken from 342 individuals from ten communities, who were microfilaria positive at pretreatment assessment, on days 90 and 180 after treatment, to identify the effects of ivermectin on female worm fertility, assessed by microfilaria repopulation. Findings: 487 (19%) of the 2501 participants were microfilaria positive. The microfilaria prevalence and community microfilarial load in treated communities ranged from 2·2% to 51·8%, and 0·06 microfilariae per snip to 2·85 microfilariae per snip, respectively. Despite treatment, the prevalence rate doubled between 2000 and 2005 in two communities. Microfilaria assessment 30 days after ivermectin treatment showed 100% clearance of microfilaria in more than 99% of people. At day 90 after treatment, four of ten communities had significant microfilaria repopulation, from 7·1% to 21·1% of pretreatment counts, rising to 53·9% by day 180. Interpretation: Ivermectin remains a potent microfilaricide. However, our results suggest that resistant adult parasite populations, which are not responding as expected to ivermectin, are emerging. A high rate of repopulation of skin with microfilariae will allow parasite transmission, possibly with ivermectin-resistant O volvulus, which could eventually lead to recrudescence of the disease. en_US
dc.language.iso en en_US
dc.publisher Elsevier Ltd. en_US
dc.subject EMTREE drug terms: ivermectin en_US
dc.subject EMTREE medical terms: adult; aged; article; drug efficacy; drug mechanism; human; infection prevention; major clinical study; microfilaria (nematode larva); Onchocerca volvulus; onchocerciasis; parasite transmission; priority journal en_US
dc.subject MeSH: Adolescent; Adult; Aged; Animals; Epidemiologic Methods; Female; Filaricides; Ghana; Humans; Ivermectin; Middle Aged; Multicenter Studies; Onchocerca volvulus; Onchocerciasis, Ocular; Prevalence; Severity of Illness Index; Skin en_US
dc.title Prevalence and intensity of Onchocerca volvulus infection and efficacy of ivermectin in endemic communities in Ghana: a two-phase epidemiological study en_US
dc.type Article en_US


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