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Katabarwa MN, Eyamba A, Nwane P, Enyong P, Yaya S, Baldiagaï J, Madi TK, Yougouda A, Andze GO, Richards FO. Seventeen years of annual distribution of ivermectin has not interrupted onchocerciasis transmission in North Region, Cameroon. Am J Trop Med Hyg 2011; 85:1041-9. [PMID: 22144441 PMCID: PMC3225149 DOI: 10.4269/ajtmh.2011.11-0333] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 08/02/2011] [Indexed: 11/07/2022] Open
Abstract
We studied onchocerciasis transmission and impact on ocular morbidity in three health districts in North Region, Cameroon, where annual mass ivermectin treatment has been provided for 12-17 years. The studies, which took place from 2008 to 2010, consisted of skin snips for microfilariae (mf), palpation examinations for nodules, slit lamp examinations for mf in the eye, and Simulium vector dissections for larval infection rates. Adults had mf and nodule rates of 4.8% and 13.5%, respectively, and 5.5% had mf in the anterior chamber of the eye. Strong evidence of ongoing transmission was found in one health district, where despite 17 years of annual treatments, the annual transmission potential was 543 L3/person per year; additionally, children under 10 years of age had a 2.6% mf prevalence. Halting ivermectin treatments in North Cameroon now might risk recrudescence of transmission and ocular disease.
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African Programme for Onchocerciasis Control: meeting of National Task Forces, September 2011. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2011; 86:541-549. [PMID: 22128386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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InterAmerican Conference on Onchocerciasis, 2010: progress towards eliminating river blindness in the WHO Region of the Americas. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2011; 86:417-423. [PMID: 21969940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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Babalola OE, Ogbuagu FK, Maegga BT, Braide EI, Magimbi C, Zoure H, Yameogo L, Seketeh A. African programme for Onchoceriasis control: ophthalmological findings in Bushenyi, Uganda. West Afr J Med 2011; 30:104-109. [PMID: 21984457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND The overall prevalence of blindness from Onchoceriasis in Bushenyi is relatively low, most of which is to be found in the elderly. Onchoceriasis is a major health problem in Africa. The Community-Directed treatment with invermectin is a control strategy to address the problem, but baseline data are generally lacking in several countries. OBJECTIVE To describe baseline ophthalmological data in order to assess the impact of Community-Directed with Ivermectin (CDTI) in Uganda. METHODS The study site was in Bushenyi, Western Uganda. In a cross-sectional study, 367 persons aged 10 years or older from seven selected villages received eye examination using a standardised protocol and Wu-Jones Motion Sensitivity Testing (MSST). Besides MSST, other information sought included visual acuity, slit lamp examination, testicular opacities and intraocular presence. RESULTS Of the 367 subjects, 219(57.2%) were males. Subjects less than 25 years of age were 104(28.3). The prevalence of blindness were 1.9% while 4.1% was visually impaired by acuity criteria alone. A further 9.1% had moderate visual field loss while 2.8% had severe field loss. There was no case of anterior chamber microfilaria but dead microfilariae were seen in two cases. Punctate keratitis was present in 1.8% with sclerosing keratitis was twice as common at 3.8%. Optic atrophy was also relatively common at 12.4%, while chorioretinitis was present in 3.3%. CONCLUSION There was an apparent paucity of acute onchocerciasis-related lesions but a significant presence of irreversible onchocerciasis-related lesions. The most significant problem requiring intervention would appear to be cataract.
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Report from the 2009 Inter-American Conference on Onchocerciasis: progress towards eliminating river blindness in the Region of the Americas. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2010; 85:321-326. [PMID: 20707042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
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Onchocerciasis (river blindness). Report from the eighteenth InterAmerican Conference on Onchocerciasis, November 2008. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2009; 84:385-389. [PMID: 19764129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Onchocerciasis: elimination is feasible. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2009; 84:382-383. [PMID: 19764128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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Fighting river blindness and other ills. Lancet 2009; 374:91. [PMID: 19595328 DOI: 10.1016/s0140-6736(09)61262-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Babalola OE, Abiose A, Barrie JR. The Problem of Trachoma within an Onchocerciasis-Endemic Zone in Kaduna: Need for a Multilateral Approach? Ophthalmic Epidemiol 2009; 12:311-9. [PMID: 16272051 DOI: 10.1080/09286580591005787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
INTRODUCTION Within the mesoendemic onchocerciasis belt of Kaduna State, Northern Nigeria, there were other causes of ocular morbidity as well. We investigated the contribution of trachoma. METHODS A total of 6831 individuals were examined for eye disease, including signs of trachoma. RESULTS The overall prevalence of trachoma was 4.5% (577 eyes of 310 individuals), making it the second most common cause (1 in 5) of ocular morbidity after cataracts. Of the 577 eyes, 405 (70.2%) had cicatrizing disease while the rest had active disease. Overall, the prevalence of TF was 1.1% (1.3% in those < 10 years of age), TI 0.2%, TS 3%, CO 0.5% and TT 1.1% (4.3% and 3.5% in subjects aged > 55 and > 40 years, respectively). The prevalence of trachoma increased with age. The overall prevalence of blindness in the whole population was 2.7%. Trachoma accounted for 11% of this. On the other hand, onchocerciasis accounted for 3.1% of the overall ocular morbidity (less than trachoma) and 39% of the blindness. CONCLUSIONS There appears to be a clear need to retrain middle cadre ivermectin workers in trachoma rapid assessment and SAFE strategy intervention methods in order to further impact blindness prevention in these 'onchocerciasis-endemic' zones.
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Babalola OE, Maegga B, Katenga S, Ogbuagu FK, Umeh RE, Seketeli E, Braide E. APOC impact assessment studies: baseline ophthalmological findings in Morogoro, Tanzania. AFRICAN JOURNAL OF MEDICINE AND MEDICAL SCIENCES 2008; 37:327-332. [PMID: 19301709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The goal of the African Programme for Onchocerciasis Control (APOC) is to eliminate Onchocerciasis as a disease of public Health significance and an important constraint to socio-economic development in the 19 none OCP (Onchocerciasis Control Project) countries covered through Community-Directed Treatment with Ivermectin, CDTI. In 1998, impact assessment studies were carried out in Morogoro, Tanzania during which baseline ophthalmological parameters were established. The hypothesis being tested is that CDTI will prevent or delay progression of onchocercal eye lesions and blindness. A total of 425 subjects aged 10 years or more from 14 villages within Bwakira district ofMorogoro region in Tanzania were examined for Snellen visual acuity, ocular microfilaria, lens opacities, uveitis and posterior segment disease especially chorioretinitis and optic nerve disease. Motion Sensitivity Screening Test (MSST) was carried out as well. Microfilaria was present in the anterior chamber of nearly half (49.2%) of all subjects examined. Prevalence of blindness was extremely high at 15.2%. Onchocercal lesions were responsible for blindness in 41.5% of these, followed by cataracts (27.7%), glaucoma (10.8%) and trachoma (6.2%). The main pathway to onchocercal blindness in this population was anterior uveitis with or without secondary cataracts. There is an urgent need to get CDTI underway and institute other horizontal primary eye care measures, especially cataract backlog reduction, in order to reduce the excessive burden of avoidable blindness in this community.
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Report from the Inter-American Conference on Onchocerciasis, November 2007. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2008; 83:256-260. [PMID: 18637266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
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Hodgkin C, Molyneux DH, Abiose A, Philippon B, Reich MR, Remme JH, Thylefors B, Traore M, Grepin K. The future of onchocerciasis control in Africa. PLoS Negl Trop Dis 2007; 1:e74. [PMID: 17989787 PMCID: PMC2041822 DOI: 10.1371/journal.pntd.0000074] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Onchocerciasis (river blindness). Report from the sixteenth InterAmerican Conference on Onchocerciasis, Antigua Guatemala, Guatemala. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2007; 82:314-6. [PMID: 17763565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
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Hopkins AD. Onchocerciasis control: impressive achievements not to be wasted. ACTA ACUST UNITED AC 2007; 42:13-5. [PMID: 17361236 DOI: 10.3129/can] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
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Osei-Atweneboana MY, Eng JK, Boakye DA, Gyapong JO, Prichard RK. Prevalence and intensity of Onchocerca volvulus infection and efficacy of ivermectin in endemic communities in Ghana: a two-phase epidemiological study. Lancet 2007; 369:2021-2029. [PMID: 17574093 DOI: 10.1016/s0140-6736(07)60942-8] [Citation(s) in RCA: 298] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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.
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Hopkins AD. Onchocerciasis control: impressive achievements not to be wasted. CANADIAN JOURNAL OF OPHTHALMOLOGY 2007. [PMID: 17361236 DOI: 10.3129/can%20j%20ophthalmol.06-105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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Abstract
The success of the Onchocerciasis Control Programme is undeniable and exemplary, say the authors, but it is too early to claim victory against river blindness.
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Onchocerciasis (river blindness). Report from the fifteenth InterAmerican Conference on Onchocerciasis, Caracas, Venezuela. RELEVE EPIDEMIOLOGIQUE HEBDOMADAIRE 2006; 81:293-6. [PMID: 16874924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
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Katholi CR, Unnasch TR. Important experimental parameters for determining infection rates in arthropod vectors using pool screening approaches. Am J Trop Med Hyg 2006; 74:779-85. [PMID: 16687680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023] Open
Abstract
Measuring transmission of a vector-borne infection is essential to understanding infection dynamics. When infection prevalence in the vector population is low, transmission is often measured by pool screening (also referred to as group testing). Several investigators have developed statistical methods to recover infection prevalence estimates from pool screen data. These are based on models that contain certain assumptions, and a pool screening approach must be designed to take these into account if accurate estimates of infection prevalence are to be obtained. Here we describe these assumptions and discuss appropriate sampling protocols. The sources of error inherent in pool screening are described, and we show that, under most conditions in which one would want to use group testing, most of the error results from sampling and not the pooling process. Issues involved in developing a sampling protocol, including the total number of insects to be screened and optimal pool size, are explored. The meaning of confidence intervals associated with prevalence estimates and the appropriate interpretation of these intervals are discussed.
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Abstract
The donation of ivermectin by Merck and Co. Inc. has led to one of the most effective private-public partnerships controlling a disease of major public health importance particularly in Africa. The up scaling of ivermectin distribution during the last 15 years has been remarkable with almost 40 million people treated in 2003, many already on their regular annual dose. The tools that have been developed particularly by the APOC programme have been instrumental in this increase. However, ivermectin is a microfilaricide and does not kill the adult worms. Distribution will be needed for at least 25 years and latest estimates indicate that 90 million people need annual treatment if onchocerciasis is to be eliminated as a public health problem. In spite of this incredible progress it is difficult to see how the programme will be sustained, especially after the closure of APOC in 2010. A macrofilaricide destroying adult worms and safe for mass distribution would solve the problem of onchocerciasis.
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Stingl P. [Onchocerciasis]. MMW Fortschr Med 2004; 146:44-5. [PMID: 15581105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
Onchocerciasis, which is caused by filarial nematodes, affects roughly 18 million people in tropical Africa and is a major cause of morbidity, with a serious sociomedical impact. Although the present onchocerciasis control strategy comprising antifilarial chemotherapy and vector control is successful, it is associated with logistic problems due to the prolonged treatment duration. Furthermore, fears of drug resistance are on the increase. New approaches involving the use of antibiotics aimed at endobacteria living in symbiosis with filariae appear promising. Recent trials with tetracycline indicate a significant impact on worm viability.
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Little MP, Basanez MG, Breitling LP, Boatin BA, Alley ES. Incidence of blindness during the Onchocerciasis control programme in western Africa, 1971-2002. J Infect Dis 2004; 189:1932-41. [PMID: 15122532 DOI: 10.1086/383326] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2003] [Accepted: 10/02/2003] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Infection with Onchocerca volvulus is associated with the prevalence of severe visual impairment and blindness. However, longitudinal studies of the incidence of blindness caused by onchocerciasis are scarce. METHODS The relationship, at the individual level, between infection with O. volvulus microfilariae and bilateral blindness was examined, by use of data collected, during the Onchocerciasis Control Programme in western Africa (OCP), from 2315 villages in 11 countries. The data were analyzed by Poisson maximum-likelihood techniques with adjustment for overdispersion. RESULTS A total of 297,756 persons were eligible for follow-up in the cohort, and, during 1971-2001, these persons accumulated 367,788 person-years of follow-up without blindness. A total of 673 bilateral cases of blindness occurred during this period; 29.7% were caused by onchocerciasis. After ivermectin therapy was introduced (during 1988-2001), only 19.6% of cases were caused by onchocerciasis. The incidence of blindness was significantly and positively associated with increasing microfilarial burden (P<.001). Overall, female subjects had an ~40% lower risk of becoming blind than did male subjects (P<.001). After an initially high incidence of blindness at the beginning of the OCP, the rate of blindness from causes other than onchocerciasis remained approximately constant during follow-up. CONCLUSIONS We demonstrate, in a comprehensive data set and in both sexes, a direct relationship between microfilarial load and the incidence of blindness.
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