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Khainza AT, Soita D, Okia D, Okello F, Matovu JKB, Lubaale Y, Byamukama E, Okibure A, Alunyo JP, Nantale R, Wanume B, Ogutu D, Mukunya D, Olupot-Olupot P. Community Involvement in Onchocerciasis Post-elimination Surveillance in Bududa District, Eastern Uganda: A cross-sectional study. PLoS Negl Trop Dis 2024; 18:e0012270. [PMID: 39012847 PMCID: PMC11251607 DOI: 10.1371/journal.pntd.0012270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 06/04/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND Globally, there are an estimated 20.9 million cases of onchocerciasis, with Africa bearing the greatest burden. The World Health Organization (WHO) has targeted the disease for elimination by 2030. As of August 2023, there were 15 foci in 37/48 (76%) districts and one city in Uganda that had reached the elimination phase. However, there is a paucity of data on community involvement in post-elimination surveillance (PES) activities. The communities in the post-elimination phase are expected to maintain surveillance, provide health education, refer cases for treatment, and participate in surveillance. However, it is not clear whether this is being done. In this study, we assessed the feasibility of community involvement in post-elimination surveillance activities in Bududa District, Eastern Uganda, to draw key generalisable lessons for similar settings. METHODS This was a cross-sectional study employing rigorous mixed methods of data collection. We used a semi-structured questionnaire to collect quantitative data on randomly sampled study participants in two sub-countries in the district. Community involvement in post-elimination surveillance (PES) was our dependent variable, measured using Yes or No questions, and our independent variables were measured on different scales. Computations of proportions and associations were done using Stata 15 software. Conversely, qualitative data were collected via focus group discussions (FGDs) for community participants and key informant interviews (KIIs) for local leaders. For the qualitative component, we had 2 FGDs, each consisting of 8 gender-balanced participants per group and 8 KIIs. Qualitative data analyses were done using a robust thematic framework approach, ensuring the reliability and validity of our findings. RESULTS A total of 422 participants with a mean age of 51.4 years (SD = 15.8) participated in the study. Community involvement in post-elimination surveillance was low (14%). Factors associated with involvements were district support [Adjusted odd ratio AOR 14, 95 CI = (2.5, 81.7)], seeing black flies in the environment in a week preceding the survey [AOR 8, 95% CI = (1.5, 42.5)], in one month [AOR 3.8, 95% CI = (1.1, 13.2)], and being a community volunteer in the Ivermectin treatment program [AOR 4.3, 95% CI = (1.03, 17.9)]. Lack of funding, poor motivation, poor program sustainability planning, and a lack of drugs at health facilities were key challenges affecting community involvement in post-elimination surveillance. CONCLUSION Community involvement in onchocerciasis post-elimination surveillance activities in Bududa District in Eastern Uganda was low but could be improved by increased district support, funding, community motivation and sensitisation.
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Affiliation(s)
- Annet Tabitha Khainza
- Department of Community and Public Health, Busitema University, Mbale, Uganda
- The Carter Center, Kampala, Uganda
| | - David Soita
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - David Okia
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - Francis Okello
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - Joseph KB Matovu
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - Yovani Lubaale
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | | | - Ambrose Okibure
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | | | - Ritah Nantale
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - Benon Wanume
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | | | - David Mukunya
- Department of Community and Public Health, Busitema University, Mbale, Uganda
| | - Peter Olupot-Olupot
- Department of Community and Public Health, Busitema University, Mbale, Uganda
- Department of Research, Mbale Clinical Research Institute, Mbale, Uganda
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Mutono N, Basáñez MG, James A, Stolk WA, Makori A, Kimani TN, Hollingsworth TD, Vasconcelos A, Dixon MA, de Vlas SJ, Thumbi SM. Elimination of transmission of onchocerciasis (river blindness) with long-term ivermectin mass drug administration with or without vector control in sub-Saharan Africa: a systematic review and meta-analysis. Lancet Glob Health 2024; 12:e771-e782. [PMID: 38484745 PMCID: PMC11009120 DOI: 10.1016/s2214-109x(24)00043-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 04/15/2024]
Abstract
BACKGROUND WHO has proposed elimination of transmission of onchocerciasis (river blindness) by 2030. More than 99% of cases of onchocerciasis are in sub-Saharan Africa. Vector control and mass drug administration of ivermectin have been the main interventions for many years, with varying success. We aimed to identify factors associated with elimination of onchocerciasis transmission in sub-Saharan Africa. METHODS For this systematic review and meta-analysis we searched for published articles reporting epidemiological or entomological assessments of onchocerciasis transmission status in sub-Saharan Africa, with or without vector control. We searched MEDLINE, PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials, African Index Medicus, and Google Scholar databases for all articles published from database inception to Aug 19, 2023, without language restrictions. The search terms used were "onchocerciasis" AND "ivermectin" AND "mass drug administration". The three inclusion criteria were (1) focus or foci located in Africa, (2) reporting of elimination of transmission or at least 10 years of ivermectin mass drug administration in the focus or foci, and (3) inclusion of at least one of the following assessments: microfilarial prevalence, nodule prevalence, Ov16 antibody seroprevalence, and blackfly infectivity prevalence. Epidemiological modelling studies and reviews were excluded. Four reviewers (NM, AJ, AM, and TNK) extracted data in duplicate from the full-text articles using a data extraction tool developed in Excel with columns recording the data of interest to be extracted, and a column where important comments for each study could be highlighted. We did not request any individual-level data from authors. Foci were classified as achieving elimination of transmission, being close to elimination of transmission, or with ongoing transmission. We used mixed-effects meta-regression models to identify factors associated with transmission status. This study is registered in PROSPERO, CRD42022338986. FINDINGS Of 1525 articles screened after the removal of duplicates, 75 provided 282 records from 238 distinct foci in 19 (70%) of the 27 onchocerciasis-endemic countries in sub-Saharan Africa. Elimination of transmission was reported in 24 (9%) records, being close to elimination of transmission in 86 (30%) records, and ongoing transmission in 172 (61%) records. I2 was 83·3% (95% CI 79·7 to 86·3). Records reporting 10 or more years of continuous mass drug administration with 80% or more therapeutic coverage of the eligible population yielded significantly higher odds of achieving elimination of transmission (log-odds 8·5 [95% CI 3·5 to 13·5]) or elimination and being close to elimination of transmission (42·4 [18·7 to 66·1]) than those with no years achieving 80% coverage or more. Reporting 15-19 years of ivermectin mass drug administration (22·7 [17·2 to 28·2]) and biannual treatment (43·3 [27·2 to 59·3]) were positively associated with elimination and being close to elimination of transmission compared with less than 15 years and no biannual mass drug administration, respectively. Having had vector control without vector elimination (-42·8 [-59·1 to -26·5]) and baseline holoendemicity (-41·97 [-60·6 to -23·2]) were associated with increased risk of ongoing transmission compared with no vector control and hypoendemicity, respectively. Blackfly disappearance due to vector control or environmental change contributed to elimination of transmission. INTERPRETATION Mass drug administration duration, frequency, and coverage; baseline endemicity; and vector elimination or disappearance are important determinants of elimination of onchocerciasis transmission in sub-Saharan Africa. Our findings underscore the importance of improving and sustaining high therapeutic coverage and increasing treatment frequency if countries are to achieve elimination of onchocerciasis transmission. FUNDING The Bill & Melinda Gates Foundation and Neglected Tropical Diseases Modelling Consortium, UK Medical Research Council, and Global Health EDCTP3 Joint Undertaking. TRANSLATIONS For the Swahili, French, Spanish and Portuguese translations of the abstract see Supplementary Materials section.
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Affiliation(s)
- Nyamai Mutono
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA.
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Ananthu James
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Anita Makori
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA
| | - Teresia Njoki Kimani
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA; Ministry of Health Kenya, Kiambu Town, Kenya
| | | | | | - Matthew A Dixon
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - S M Thumbi
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA; Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
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Otabil KB, Basáñez MG, Ankrah B, Bart-Plange EJ, Babae TN, Kudzordzi PC, Darko VA, Raji AS, Datsa L, Boakye AA, Yeboah MT, Fodjo JNS, Schallig HDFH, Colebunders R. Non-adherence to ivermectin in onchocerciasis-endemic communities with persistent infection in the Bono Region of Ghana: a mixed-methods study. BMC Infect Dis 2023; 23:805. [PMID: 37974087 PMCID: PMC10655298 DOI: 10.1186/s12879-023-08806-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Accepted: 11/08/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND The World Health Organization has proposed that onchocerciasis elimination (interruption) of transmission be verified in 12 (approximately a third) endemic countries by 2030. The strategy to reach this goal is based on ivermectin Mass Drug Administration (MDA) with high geographical and therapeutic coverage. In addition to coverage, high levels of treatment adherence are paramount. We investigated factors associated with ivermectin intake in an area of Ghana with persistent Onchocerca volvulus infection. METHODS In August 2021, a cross-sectional mixed-methods study was conducted in 13 onchocerciasis-endemic communities in the Bono Region of Ghana. Individuals aged ≥ 10 years were invited to participate in a questionnaire survey. A total of 48 focus group discussions and in-depth interviews with 10 community drug distributors and 13 community leaders were conducted. RESULTS A total of 510 people participated in the study [median age: 32, interquartile range 30 (20‒50) years]; 274 (53.7%) were females. Of the total, 320 (62.7%) declared that they adhered to each treatment round and 190 (37.3%) admitted they had not taken ivermectin during at least one MDA round, since becoming eligible for treatment. Of 483 participants with complete information, 139 (28.8%) did not take ivermectin during the last round (March 2021), and 24 (5.0%) had never taken ivermectin (systematic non-adherers). Reasons for not taking ivermectin included previous experience/fear of side-effects, being absent during MDA, pregnancy, the desire to drink alcohol, and drug distribution challenges. Being male, having good knowledge and perception of the disease, and not having secondary or higher level of formal education were significantly associated with higher odds of ivermectin intake. CONCLUSIONS A relatively high level of non-adherence to ivermectin treatment was documented. There is a need for targeted educational and behavioural change campaigns to reverse these trends and ensure a steady course toward meeting onchocerciasis elimination targets in Ghana.
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Affiliation(s)
- Kenneth Bentum Otabil
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana.
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana.
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis (MRC GIDA), London Centre for Neglected Tropical Disease Research, School of Public Health, Imperial College London, London, UK
| | - Blessing Ankrah
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Emmanuel John Bart-Plange
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Theophilus Nti Babae
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Prince-Charles Kudzordzi
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Vera Achiaa Darko
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- STU Clinic, Sunyani Technical University, Sunyani, Bono Region, Ghana
| | - Abdul Sakibu Raji
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Lydia Datsa
- Deo Gratias Medical Laboratories, Sunyani, Bono Region, Ghana
| | | | - Michael Tawiah Yeboah
- Ghana Health Service, Regional Neglected Tropical Diseases (RNTD) Office, Regional Health Directorate, Sunyani, Bono Region, Ghana
| | - Joseph Nelson Siewe Fodjo
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Henk D F H Schallig
- Department of Medical Microbiology, Experimental Parasitology Unit, Academic Medical Centre at the University of Amsterdam, Amsterdam University Medical Centres, Amsterdam, The Netherlands
| | - Robert Colebunders
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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Kura K, Milton P, Hamley JID, Walker M, Bakajika DK, Kanza EM, Opoku NO, Howard H, Nigo MM, Asare S, Olipoh G, Attah SK, Mambandu GL, Kennedy KK, Kataliko K, Mumbere M, Halleux CM, Hopkins A, Kuesel AC, Kinrade S, Basáñez MG. Can mass drug administration of moxidectin accelerate onchocerciasis elimination in Africa? Philos Trans R Soc Lond B Biol Sci 2023; 378:20220277. [PMID: 37598705 PMCID: PMC10440165 DOI: 10.1098/rstb.2022.0277] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/11/2023] [Indexed: 08/22/2023] Open
Abstract
Epidemiological and modelling studies suggest that elimination of Onchocerca volvulus transmission (EoT) throughout Africa may not be achievable with annual mass drug administration (MDA) of ivermectin alone, particularly in areas of high endemicity and vector density. Single-dose Phase II and III clinical trials demonstrated moxidectin's superiority over ivermectin for prolonged clearance of O. volvulus microfilariae. We used the stochastic, individual-based EPIONCHO-IBM model to compare the probabilities of reaching EoT between ivermectin and moxidectin MDA for a range of endemicity levels (30 to 70% baseline microfilarial prevalence), treatment frequencies (annual and biannual) and therapeutic coverage/adherence values (65 and 80% of total population, with, respectively, 5 and 1% of systematic non-adherence). EPIONCHO-IBM's projections indicate that biannual (six-monthly) moxidectin MDA can reduce by half the number of years necessary to achieve EoT in mesoendemic areas and might be the only strategy that can achieve EoT in hyperendemic areas. Data needed to improve modelling projections include (i) the effect of repeated annual and biannual moxidectin treatment; (ii) inter- and intra-individual variation in response to successive treatments with moxidectin or ivermectin; (iii) the effect of moxidectin and ivermectin treatment on L3 development into adult worms; and (iv) patterns of adherence to moxidectin and ivermectin MDA. This article is part of the theme issue 'Challenges in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield AL9 7TA, UK
| | - Didier K. Bakajika
- Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN), African Regional Office of the World Health Organization (WHO/AFRO/ESPEN), Brazzaville, Democratic Republic of Congo
| | - Eric M. Kanza
- Programme Nationale de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive (PNLMTN-CTP), Ministère de la Santé Publique, Kinshasa, Democratic Republic of the Congo
| | - Nicholas O. Opoku
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Hayford Howard
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Maurice M. Nigo
- Institut Supérieur des Techniques Médicales de Nyankunde, Bunia, Democratic Republic of the Congo
| | | | - George Olipoh
- Precious Minerals Marketing Company, National Assay Centre, Technical Department, Diamond House, Accra, GA-143-2548, Ghana
| | - Simon K. Attah
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, Accra, Ghana
| | - Germain L. Mambandu
- Inspection Provinciale de la Santé de la Tshopo, Kisangani, Democratic Republic of the Congo
| | - Kambale Kasonia Kennedy
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Kambale Kataliko
- Centre de Santé CECA 20 de Mabakanga, Beni, Nord Kivu, Democratic Republic of the Congo
| | - Mupenzi Mumbere
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Christine M. Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Gravesend, Kent DA11 OSL, UK
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Sally Kinrade
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
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Post RJ, Laudisoit A, Mandro M, Lakwo T, Laemmer C, Pfarr K, Hoerauf A, Tortosa P, Gomard Y, Ukety T, Mande C, Farovitch L, Amazigo U, Bakajika D, Oguttu DW, Awaca N, Colebunders R. Identification of the onchocerciasis vector in the Kakoi-Koda focus of the Democratic Republic of Congo. PLoS Negl Trop Dis 2022; 16:e0010684. [PMID: 36331979 PMCID: PMC9668120 DOI: 10.1371/journal.pntd.0010684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2022] [Revised: 11/16/2022] [Accepted: 10/17/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND The objective of this study was to characterise the vector in a small hyper-endemic focus of onchocerciasis (the Kakoi-Koda focus) which has recently been discovered on the western slopes of the rift valley above Lake Albert. METHODOLOGY/PRINCIPAL FINDINGS Aquatic stages of blackflies were collected by hand from streams and rivers, and anthropophilic adult females were collected by human landing catches. Using a combination of morphotaxonomy and DNA barcoding, the blackflies collected biting humans within the focus were identified as Simulium dentulosum and Simulium vorax, which were also found breeding in local streams and rivers. Simulium damnosum s.l., Simulium neavei and Simulium albivirgulatum were not found (except for a single site in 2009 where crabs were carrying S. neavei). Anthropophilic specimens from the focus were screened for Onchocerca DNA using discriminant qualitative real-time triplex PCR. One specimen of S. vorax was positive for Onchocerca volvulus in the body, and out of 155 S. dentulosum, 30% and 11% were infected and infective (respectively). CONCLUSIONS/SIGNIFICANCE Simulium dentulosum currently appears to be the main vector of human onchocerciasis within the Kakoi-Koda focus, and S. vorax may be a secondary vector. It remains possible that S. neavei was the main (or only) vector in the past having now become rare as a result of the removal of tree-cover and land-use changes. Simulium vorax has previously been shown to support the development of O. volvulus in the laboratory, but this is the first time that S. dentulosum has been implicated as a probable vector of onchocerciasis, and this raises the possibility that other blackfly species which are not generally considered to be anthropophilic vectors might become vectors under suitable conditions. Because S. dentulosum is not a vector in endemic areas surrounding the Kakoi-Koda focus, it is probable that the Kakoi-Koda focus is significantly isolated.
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Affiliation(s)
- Rory J. Post
- Disease Control Department, London School of Hygiene & Tropical Medicine, London, United Kingdom
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
| | - Anne Laudisoit
- EcoHealth Alliance, New York, New York, United States
- Global Health Institute, University of Antwerp, Wilrijk, Belgium
- Evolutionary Ecology group (EVECO), University of Antwerp, Wilrijk, Belgium
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia, Democratic Republic of Congo
| | - Thomson Lakwo
- Division of Vector Borne and Neglected Tropical Diseases Control, Ministry of Health, Kampala, Uganda
| | - Christine Laemmer
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Kenneth Pfarr
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Germany
| | - Pablo Tortosa
- Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", CNRS 9192, INSERM U 1187, IRD 249. Plateforme de Recherche CYROI, Saint-Denis, France
| | - Yann Gomard
- Université de La Réunion, UMR PIMIT "Processus Infectieux en Milieu Insulaire Tropical", CNRS 9192, INSERM U 1187, IRD 249. Plateforme de Recherche CYROI, Saint-Denis, France
| | - Tony Ukety
- Centre de Recherche en Maladies Tropicales (CRMT), Rethy, Democratic Republic of Congo
| | - Claude Mande
- Department of Ecology and Wildlife Management, University of Kisangani, Kisangani, Democratic Republic of Congo
- Biodiversity Monitoring Centre (CSB), University of Kisangani, Kisangani, Democratic Republic of Congo
| | - Lorne Farovitch
- School of Medicine and Dentistry, University of Rochester Medical Center, Rochester New York, United States of America
| | - Uche Amazigo
- Pan-African Community Initiative on Education and Health, Enugu, Nigeria
| | - Didier Bakajika
- Expanded Special Project for Elimination of NTDs, World Health Organization Regional Office for Africa, Brazzaville, Republic of Congo
| | - David W. Oguttu
- Division of Vector Borne and Neglected Tropical Diseases Control, Ministry of Health, Kampala, Uganda
| | - Naomi Awaca
- Ministry of Health, National Programme for Neglected Tropical Diseases & Preventive Chemotherapy, Kinshasa, Democratic Republic of Congo
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Wilrijk, Belgium
- * E-mail:
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Schmidt CA, Cromwell EA, Hill E, Donkers KM, Schipp MF, Johnson KB, Pigott DM, Hay SI. The prevalence of onchocerciasis in Africa and Yemen, 2000-2018: a geospatial analysis. BMC Med 2022; 20:293. [PMID: 36068517 PMCID: PMC9449300 DOI: 10.1186/s12916-022-02486-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 07/14/2022] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Onchocerciasis is a disease caused by infection with Onchocerca volvulus, which is transmitted to humans via the bite of several species of black fly, and is responsible for permanent blindness or vision loss, as well as severe skin disease. Predominantly endemic in parts of Africa and Yemen, preventive chemotherapy with mass drug administration of ivermectin is the primary intervention recommended for the elimination of its transmission. METHODS A dataset of 18,116 geo-referenced prevalence survey datapoints was used to model annual 2000-2018 infection prevalence in Africa and Yemen. Using Bayesian model-based geostatistics, we generated spatially continuous estimates of all-age 2000-2018 onchocerciasis infection prevalence at the 5 × 5-km resolution as well as aggregations to the national level, along with corresponding estimates of the uncertainty in these predictions. RESULTS As of 2018, the prevalence of onchocerciasis infection continues to be concentrated across central and western Africa, with the highest mean estimates at the national level in Ghana (12.2%, 95% uncertainty interval [UI] 5.0-22.7). Mean estimates exceed 5% infection prevalence at the national level for Cameroon, Central African Republic, Democratic Republic of the Congo (DRC), Guinea-Bissau, Sierra Leone, and South Sudan. CONCLUSIONS Our analysis suggests that onchocerciasis infection has declined over the last two decades throughout western and central Africa. Focal areas of Angola, Cameroon, the Democratic Republic of the Congo, Ethiopia, Ghana, Guinea, Mali, Nigeria, South Sudan, and Uganda continue to have mean microfiladermia prevalence estimates exceeding 25%. At and above this level, the continuation or initiation of mass drug administration with ivermectin is supported. If national programs aim to eliminate onchocerciasis infection, additional surveillance or supervision of areas of predicted high prevalence would be warranted to ensure sufficiently high coverage of program interventions.
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Affiliation(s)
- Chris A Schmidt
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA.
| | - Elizabeth A Cromwell
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - Elex Hill
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - Katie M Donkers
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - Megan F Schipp
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - Kimberly B Johnson
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | - David M Pigott
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
| | | | - Simon I Hay
- Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, 98121, USA
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7
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Tirados I, Thomsen E, Worrall E, Koala L, Melachio TT, Basáñez MG. Vector control and entomological capacity for onchocerciasis elimination. Trends Parasitol 2022; 38:591-604. [DOI: 10.1016/j.pt.2022.03.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/17/2022] [Accepted: 03/08/2022] [Indexed: 11/24/2022]
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8
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Hopkins DR, Ijaz K, Weiss A, Roy SL, Ross DA. Reply to: Rethinking disease eradication: putting countries first. Int Health 2021; 13:648-649. [PMID: 34532741 PMCID: PMC8643430 DOI: 10.1093/inthealth/ihab055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/13/2021] [Accepted: 08/24/2021] [Indexed: 11/13/2022] Open
Affiliation(s)
- Donald R Hopkins
- The Carter Center, 453 John Lewis Freedom Parkway, Atlanta, GA 30307, USA
| | - Kashef Ijaz
- The Carter Center, 453 John Lewis Freedom Parkway, Atlanta, GA 30307, USA
| | - Adam Weiss
- The Carter Center, 453 John Lewis Freedom Parkway, Atlanta, GA 30307, USA
| | - Sharon L Roy
- Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop H24-3, Atlanta, GA 30329, USA
| | - David A Ross
- The Task Force for Global Health, 330 W. Ponce de Leon Avenue, Decatur, GA 30030, USA
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9
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The burden of skin disease and eye disease due to onchocerciasis in countries formerly under the African Programme for Onchocerciasis Control mandate for 1990, 2020, and 2030. PLoS Negl Trop Dis 2021; 15:e0009604. [PMID: 34310602 PMCID: PMC8312930 DOI: 10.1371/journal.pntd.0009604] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 06/29/2021] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Onchocerciasis ("river blindness") can cause severe morbidity, including vision loss and various skin manifestations, and is targeted for elimination using ivermectin mass drug administration (MDA). We calculated the number of people with Onchocerca volvulus infection and onchocercal skin and eye disease as well as disability-adjusted life years (DALYs) lost from 1990 through to 2030 in areas formerly covered by the African Programme for Onchocerciasis Control. METHODS Per MDA implementation unit, we collated data on the pre-control distribution of microfilariae (mf) prevalence and the history of control. Next, we predicted trends in infection and morbidity over time using the ONCHOSIM simulation model. DALY estimates were calculated using disability weights from the Global Burden of Disease Study. RESULTS In 1990, prior to MDA implementation, the total population at risk was 79.8 million with 26.0 million (32.5%) mf-positive individuals, of whom 17.5 million (21.9%) had some form of onchocercal skin or eye disease (2.5 million DALYs lost). By 2030, the total population was predicted to increase to 236.1 million, while the number of mf-positive cases (about 6.8 million, 2.9%), people with skin or eye morbidity (4.2 million, 1.8%), and DALYs lost (0.7 million) were predicted to decline. CONCLUSIONS MDA has had a remarkable impact on the onchocerciasis burden in countries previously under the APOC mandate. In the few countries where we predict continued transmission between now and 2030, intensified MDA could be combined with local vector control efforts, or the introduction of new drugs for mopping up residual cases of infection and morbidity.
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10
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Niamsi-Emalio Y, Nana-Djeunga HC, Chesnais CB, Pion SDS, Tchatchueng-Mbougua JB, Boussinesq M, Basáñez MG, Kamgno J. Unusual Localization of Blood-Borne Loa loa Microfilariae in the Skin Depends on Microfilarial Density in the Blood: Implications for Onchocerciasis Diagnosis in Coendemic Areas. Clin Infect Dis 2021; 72:S158-S164. [PMID: 33909066 PMCID: PMC8201578 DOI: 10.1093/cid/ciab255] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Background The diagnostic gold standard for onchocerciasis relies on identification and enumeration of (skin-dwelling) Onchocerca volvulus microfilariae (mf) using the skin snip technique (SST). In a recent study, blood-borne Loa loa mf were found by SST in individuals heavily infected with L. loa, and microscopically misidentified as O. volvulus due to their superficially similar morphology. This study investigates the relationship between L. loa microfilarial density (Loa MFD) and the probability of testing SST positive. Methods A total of 1053 participants from the (onchocerciasis and loiasis coendemic) East Region in Cameroon were tested for (1) Loa MFD in blood samples, (2) O. volvulus presence by SST, and (3) Immunoglobulin (Ig) G4 antibody positivity to Ov16 by rapid diagnostic test (RDT). A Classification and Regression Tree (CART) model was used to perform a supervised classification of SST status and identify a Loa MFD threshold above which it is highly likely to find L. loa mf in skin snips. Results Of 1011 Ov16-negative individuals, 28 (2.8%) tested SST positive and 150 (14.8%) were L. loa positive. The range of Loa MFD was 0–85 200 mf/mL. The CART model subdivided the sample into 2 Loa MFD classes with a discrimination threshold of 4080 (95% CI, 2180–12 240) mf/mL. The probability of being SST positive exceeded 27% when Loa MFD was >4080 mf/mL. Conclusions The probability of finding L. loa mf by SST increases significantly with Loa MFD. Skin-snip polymerase chain reaction would be useful when monitoring onchocerciasis prevalence by SST in onchocerciasis–loiasis coendemic areas.
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Affiliation(s)
- Yannick Niamsi-Emalio
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Hugues C Nana-Djeunga
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Cédric B Chesnais
- Institut de Recherche pour le Développement (IRD), UMI233/INSERM U1175, Université de Montpellier , Montpellier, France
| | - Sébastien D S Pion
- Institut de Recherche pour le Développement (IRD), UMI233/INSERM U1175, Université de Montpellier , Montpellier, France
| | - Jules B Tchatchueng-Mbougua
- Service d'Epidémiologie, Centre Pasteur du Cameroun, Membre du Réseau International des Instituts Pasteur, Yaoundé, Cameroun
| | - Michel Boussinesq
- Institut de Recherche pour le Développement (IRD), UMI233/INSERM U1175, Université de Montpellier , Montpellier, France
| | - María-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Dep artment of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon.,Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
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11
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Stolk WA, Blok DJ, Hamley JID, Cantey PT, de Vlas SJ, Walker M, Basáñez MG. Scaling-Down Mass Ivermectin Treatment for Onchocerciasis Elimination: Modeling the Impact of the Geographical Unit for Decision Making. Clin Infect Dis 2021; 72:S165-S171. [PMID: 33909070 PMCID: PMC8201558 DOI: 10.1093/cid/ciab238] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Background Due to spatial heterogeneity in onchocerciasis transmission, the duration of ivermectin mass drug administration (MDA) required for eliminating onchocerciasis will vary within endemic areas and the occurrence of transmission “hotspots” is inevitable. The geographical scale at which stop-MDA decisions are made will be a key driver in how rapidly national programs can scale down active intervention upon achieving the epidemiological targets for elimination. Methods We used 2 onchocerciasis models (EPIONCHO-IBM and ONCHOSIM) to predict the likelihood of achieving elimination by 2030 in Africa, accounting for variation in preintervention endemicity levels and histories of ivermectin treatment. We explore how decision making at contrasting geographical scales (community vs larger scale “project”) changes projections on populations still requiring MDA or transitioning to post-treatment surveillance. Results The total population considered grows from 118 million people in 2020 to 136 million in 2030. If stop-MDA decisions are made at project level, the number of people requiring treatment declines from 69–118 million in 2020 to 59–118 million in 2030. If stop-MDA decisions are made at community level, the numbers decline from 23–81 million in 2020 to 15–63 million in 2030. The lower estimates in these prediction intervals are based on ONCHOSIM, the upper limits on EPIONCHO-IBM. Conclusions The geographical scale at which stop-MDA decisions are made strongly determines how rapidly national onchocerciasis programs can scale down MDA programs. Stopping in portions of project areas or transmission zones would free up human and economic resources.
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Affiliation(s)
- Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - David J Blok
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Jonathan I D Hamley
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's Campus), Imperial College London, London, United Kingdom.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's Campus), Imperial College London, London, United Kingdom
| | - Paul T Cantey
- Division of Parasitic Diseases and Malaria, US Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's Campus), Imperial College London, London, United Kingdom.,London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield, United Kingdom
| | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's Campus), Imperial College London, London, United Kingdom.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's Campus), Imperial College London, London, United Kingdom
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12
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Brattig NW, Cheke RA, Garms R. Onchocerciasis (river blindness) - more than a century of research and control. Acta Trop 2021; 218:105677. [PMID: 32857984 DOI: 10.1016/j.actatropica.2020.105677] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2020] [Revised: 08/06/2020] [Accepted: 08/21/2020] [Indexed: 12/14/2022]
Abstract
This review summarises more than a century of research on onchocerciasis, also known as river blindness, and its control. River blindness is an infection caused by the tissue filaria Onchocerca volvulus affecting the skin, subcutaneous tissue and eyes and leading to blindness in a minority of infected persons. The parasite is transmitted by its intermediate hosts Simulium spp. which breed in rivers. Featured are history and milestones in onchocerciasis research and control, state-of-the-art data on the parasite, its endobacteria Wolbachia, on the vectors, previous and current prevalence of the infection, its diagnostics, the interaction between the parasite and its host, immune responses and the pathology of onchocerciasis. Detailed information is documented on the time course of control programmes in the afflicted countries in Africa and the Americas, a long road from previous programmes to current successes in control of the transmission of this infectious disease. By development, adjustment and optimization of the control measures, transmission by the vector has been interrupted in foci of countries in the Americas, in Uganda, in Sudan and elsewhere, followed by onchocerciasis eliminations. The current state and future perspectives for control, elimination and eradication within the next 20-30 years are described and discussed. This review contributes to a deeper comprehension of this disease by a tissue-dwelling filaria and it will be helpful in efforts to control and eliminate other filarial infections.
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13
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Hamley JID, Blok DJ, Walker M, Milton P, Hopkins AD, Hamill LC, Downs P, de Vlas SJ, Stolk WA, Basáñez MG. What does the COVID-19 pandemic mean for the next decade of onchocerciasis control and elimination? Trans R Soc Trop Med Hyg 2021; 115:269-280. [PMID: 33515042 PMCID: PMC7928565 DOI: 10.1093/trstmh/traa193] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/16/2020] [Accepted: 12/29/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Mass drug administration (MDA) of ivermectin for onchocerciasis has been disrupted by the coronavirus disease 2019 (COVID-19) pandemic. Mathematical modelling can help predict how missed/delayed MDA will affect short-term epidemiological trends and elimination prospects by 2030. METHODS Two onchocerciasis transmission models (EPIONCHO-IBM and ONCHOSIM) are used to simulate microfilarial prevalence trends, elimination probabilities and age profiles of Onchocerca volvulus microfilarial prevalence and intensity for different treatment histories and transmission settings, assuming no interruption, a 1-y (2020) interruption or a 2-y (2020-2021) interruption. Biannual MDA or increased coverage upon MDA resumption are investigated as remedial strategies. RESULTS Programmes with shorter MDA histories and settings with high pre-intervention endemicity will be the most affected. Biannual MDA is more effective than increasing coverage for mitigating COVID-19's impact on MDA. Programmes that had already switched to biannual MDA should be minimally affected. In high-transmission settings with short treatment history, a 2-y interruption could lead to increased microfilarial load in children (EPIONCHO-IBM) and adults (ONCHOSIM). CONCLUSIONS Programmes with shorter (annual MDA) treatment histories should be prioritised for remedial biannual MDA. Increases in microfilarial load could have short- and long-term morbidity and mortality repercussions. These results can guide decision-making to mitigate the impact of COVID-19 on onchocerciasis elimination.
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Affiliation(s)
- Jonathan I D Hamley
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK
| | - David J Blok
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK.,London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield AL9 7TA, UK
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK
| | - Adrian D Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Kent, UK
| | - Louise C Hamill
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Philip Downs
- Sightsavers, 35 Perrymount Road, Haywards Heath, RH16 3BW, UK
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK.,MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, Norfolk Place, London W2 1PG, UK
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14
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Cheke RA, Little KE, Young S, Walker M, Basáñez MG. Taking the strain out of onchocerciasis? A reanalysis of blindness and transmission data does not support the existence of a savannah blinding strain of onchocerciasis in West Africa. ADVANCES IN PARASITOLOGY 2021; 112:1-50. [PMID: 34024357 DOI: 10.1016/bs.apar.2021.01.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Onchocerciasis (also known as 'river blindness'), is a neglected tropical disease (NTD) caused by the (Simulium-transmitted) filarial nematode Onchocerca volvulus. The occurrence of 'blinding' (savannah) and non-blinding (forest) parasite strains and the existence of corresponding, locally adapted Onchocerca-Simulium complexes were postulated to explain greater blindness prevalence in savannah than in forest foci. As a result, the World Health Organization (WHO) Onchocerciasis Control Programme in West Africa (OCP) focused anti-vectorial and anti-parasitic interventions in savannah endemic areas. In this paper, village-level data on blindness prevalence, microfilarial prevalence, and transmission intensity (measured by the annual transmission potential, the number of infective, L3, larvae per person per year) were extracted from 16 West-Central Africa-based publications, and analysed according to habitat (forest, forest-savannah mosaic, savannah) to test the dichotomous strain hypothesis in relation to blindness. When adjusting for sample size, there were no statistically significant differences in blindness prevalence between the habitats (one-way ANOVA, P=0.68, mean prevalence for forest=1.76±0.37 (SE); mosaic=1.49±0.38; savannah=1.89±0.26). The well-known relationship between blindness prevalence and annual transmission potential for savannah habitats was confirmed and shown to hold for (but not to be statistically different from) forest foci (excluding data from southern Côte d'Ivoire, in which blindness prevalence was significantly lower than in other West African forest communities, but which had been the focus of studies leading to the strain-blindness hypothesis that was accepted by OCP planners). We conclude that the evidence for a savannah blinding onchocerciasis strain in simple contrast with a non-blinding forest strain is equivocal. A re-appraisal of the strain hypothesis to explain patterns of ocular disease is needed to improve understanding of onchocerciasis epidemiology and disease burden estimates in the light of the WHO 2030 goals for onchocerciasis.
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Affiliation(s)
- Robert A Cheke
- Natural Resources Institute, Department of Agriculture, Health & Environment, University of Greenwich at Medway, Kent, United Kingdom; London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom
| | | | - Stephen Young
- Natural Resources Institute, Department of Agriculture, Health & Environment, University of Greenwich at Medway, Kent, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Populations Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom; MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, London, United Kingdom.
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15
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Progress towards onchocerciasis elimination in Côte d'Ivoire: A geospatial modelling study. PLoS Negl Trop Dis 2021; 15:e0009091. [PMID: 33566805 PMCID: PMC7875389 DOI: 10.1371/journal.pntd.0009091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 01/01/2021] [Indexed: 11/19/2022] Open
Abstract
Background Côte d’Ivoire has had 45 years of intervention for onchocerciasis by vector control (from 1975 to 1991), ivermectin mass drug administration (MDA) (from 1992 to 1994) and community directed treatment with ivermectin (CDTi) from 1995 to the present. We modeled onchocerciasis endemicity during two time periods that correspond to the scale up of vector control and ivermectin distribution, respectively. This analysis illustrates progress towards elimination during these periods, and it has identified potential hotspots areas that are at risk for ongoing transmission. Methods and findings The analysis used Ministry of Health skin snip microfilaria (MF) prevalence and intensity data collected between 1975 and 2016. Socio-demographic and environmental factors were incorporated into a predictive, machine learning algorithm to create continuous maps of onchocerciasis endemicity. Overall predicted mean MF prevalence decreased from 51.8% circa 1991 to 3.9% circa 2016. The model predicted infection foci with higher prevalence in the southern region of the country. Predicted mean community MF load (CMFL) decreased from 10.1MF/snip circa 1991 to 0.1MF/snip circa 2016. Again, the model predicts foci with higher Mf densities in the southern region. For assessing model performance, the root mean squared error and R2 values were 1.14 and 0.62 respectively for a model trained with data collected prior to 1991, and 1.28 and 0.57 for the model trained with infection survey data collected later, after the introduction of ivermectin. Finally, our models show that proximity to permanent inland bodies of water and altitude were the most informative variables that correlated with onchocerciasis endemicity. Conclusion/Significance This study further documents the significant reduction of onchocerciasis infection following widespread use of ivermectin for onchocerciasis control in Côte d’Ivoire. Maps produced predict areas at risk for ongoing infection and transmission. Onchocerciasis might be eliminated in Côte d’Ivoire in the future with a combination of sustained CDTi with high coverage, active surveillance, and close monitoring for persistent infection in previously hyper-endemic areas. Côte d’Ivoire is endemic for onchocerciasis (also known as “river blindness”). This neglected tropical disease is transmitted by biting black flies that breed in fast flowing rivers. From 1975 to 1991, onchocerciasis control was based on weekly aerial spraying of the insecticide temephos, on black fly breeding sites. Vector control, however, was mostly focused on the northern and central parts of the country. From 1992 to present, mass treatment with ivermectin was implemented in all endemic areas, including forested regions in the south. Here we present the first geospatial estimates of onchocerciasis endemicity over time. Using the machine learning algorithm quantile regression forest, we implemented models to: identify important socio-demographic and environmental factors that correlate with onchocerciasis infection; predict the prevalence and density of infection in areas without ground-truth data; delineate remaining infection hotspots. Our results show that Côte d’Ivoire has made very significant progress in reducing infection parameters over time, and they may help to inform future interventions to achieve the goal of onchocerciasis elimination in Côte d’Ivoire.
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16
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Katabarwa MN, Habomugisha P, Khainza A, Oguttu D, Byamukama E, Katamanywa J, Isingooma T, Bwenume F, Nahabwe C, Ngabirano M, Akampurira P, Bernard L, Unnasch TR, Richards F. Elimination of Simulium neavei-Transmitted Onchocerciasis in Wambabya-Rwamarongo Focus of Western Uganda. Am J Trop Med Hyg 2020; 103:1135-1142. [PMID: 32588807 PMCID: PMC7470550 DOI: 10.4269/ajtmh.20-0195] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Wambabya–Rwamarongo onchocerciasis focus is one of the eight foci Uganda verified using the WHO verification guidelines. The approach for elimination was twice yearly treatment with ivermectin for every round, treating at least 90% of all the eligible population. This was in combination with vector elimination using Abate® (BASF SE, Limburgerhof, Germany) since elimination nationwide policy was launched. From 2008 to 2013, the program distributed ivermectin with a mean treatment coverage of the ultimate treatment goal (UTG) or eligible population of 91.2%, with a range of 85–96%. In 2009, vector elimination based on ground larviciding had a dramatic impact on the Simulium vectors, as the last fly was observed in October 2009. No more Simulium vectors were observed during a period of at least 7 years, including the 3-year posttreatment surveillance (PTS) until the focus was reclassified as eliminated in August 2017. During the PTS period, none of the 10,578 trapped crabs were found infested with the aquatic stages of the vector. The last infested crab was observed in March 2010, and for at least 7 years, no infested crabs were observed. Serological surveys showed that of 2,978 young children examined in 2013, only one was OV16 positive (0.0%; 95% CI: 0–0.21). In 2017, after the PTS period, all 3,079 young children examined were negative for OV16 (95% CI: 0–0.16). Therefore, entomological and serological results provided evidence that resulted in the reclassification of Wambabya–Rwamarongo focus from “transmission interrupted” to “transmission eliminated” with no possibility of recrudescence.
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Affiliation(s)
| | | | | | - David Oguttu
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | | | | | | | | | - Paul Akampurira
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | - Thomas R Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
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17
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Lakwo T, Oguttu D, Ukety T, Post R, Bakajika D. Onchocerciasis Elimination: Progress and Challenges. Res Rep Trop Med 2020; 11:81-95. [PMID: 33117052 PMCID: PMC7548320 DOI: 10.2147/rrtm.s224364] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 08/16/2020] [Indexed: 01/08/2023] Open
Abstract
Onchocerciasis is a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted through the bites of black flies of the genus Similium that breed in rivers and streams. The impact of mass treatment with ivermectin and supplemented by vector control in some countries has changed the global scene of onchocerciasis. There has been reported progress made in elimination of onchocerciasis in central and southern American countries and in some localities in Africa. The target for elimination in the Americas has been set at 2022 while for 12 countries in Africa this is expected in 2030. This review was conducted to examine the current status of onchocerciasis elimination at the global level and report on progress made. Literature searches were made through PubMed, articles in English or English abstracts, reports and any other relevant articles related to the subject. The global burden of onchocerciasis is progressively reducing and is no longer a public health problem in some regions. However, programs are challenged with a range of issues: cross-border transmission, diagnostic tools, Loa loa co-endemicity, limited workforce in entomology and maintaining enthusiasm among community drug distributors. More concerted effort using appropriate tools is required to overcome the challenges.
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Affiliation(s)
- Thomson Lakwo
- Neglected Tropical Disease Control Program, Vector Control Division, Ministry of Health, Kampala, Uganda
| | - David Oguttu
- Neglected Tropical Disease Control Program, Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Tony Ukety
- Centre de Recherche pour les Maladies Tropicales, Rethy, Ituri Province, The Democratic Republic of the Congo
| | - Rory Post
- Disease Control Department, London School of Hygiene & Tropical Medicine, London, UK.,School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| | - Didier Bakajika
- Expanded Special Project for Elimination of Neglected Tropical Diseases, WHO Regional Office for Africa, Brazzaville, Congo
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Katabarwa MN, Habomugisha P, Khainza A, Oguttu DW, Byamukama E, Katamanywa J, Nahabwe C, Ngabirano M, Akampurira P, Bernard L, Unnasch TR, Richards F. Historical Elimination of Onchocerciasis from Victoria Nile Focus in Central Uganda Verified Using WHO Criteria. Am J Trop Med Hyg 2020; 102:1411-1416. [PMID: 32228786 DOI: 10.4269/ajtmh.20-0064] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Uganda has verified elimination of seven onchocerciasis foci since 2007 when the nationwide onchocerciasis elimination policy was launched. However, the Victoria Nile focus (which was eliminated in the early 1970s) had not been verified. The objective of this study was to verify this focus to the WHO verification guidelines and bring it in line with recently eliminated foci. Vector control with dichlorodiphenyltrichloroethane was the main intervention used at the Victoria Nile from the 1950s to the 1970s. Historical fly collection sites along River Nile were identified for recent fly collection. Relevant health workers near the sites were trained to supervise fly collection activity. With support from communities, fly collectors were identified, trained, and equipped to collect Simulium flies for at least a year. A total of 854 Simulium flies were collected and analyzed by polymerase chain reaction to detect Onchocerca volvulus DNA. The communities and their leaders provided consent for the collection of dry blood spots (DBS) from children younger than 10 years for investigation of recent exposure to the disease. A total of 2,953 DBS were collected and analyzed by OV16 ELISA to detect the presence of IgG4 antibodies recognizing the OV16 antigen. The results showed that none of the flies carried O. volvulus DNA. Similarly, all the children were OV16 negative, showing no exposure to onchocerciasis. All the flies collected were identified as Simulium adersi, which is not a known vector for O. volvulus. The results confirmed that onchocerciasis and its vector Simulium damnosum had been eliminated in the Victoria Nile focus.
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Affiliation(s)
| | | | | | - David W Oguttu
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | | | | | - Paul Akampurira
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | - Thomas R Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
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19
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Cozart D, Lakwo T, Liu C, Loum D, Jacob B, Cupp EW, Unnasch TR. Identification of Human-Derived Attractants to Simulium damnosum Sensu Stricto in the Madi-Mid North Onchocerciasis Focus of Uganda. Am J Trop Med Hyg 2020; 103:1563-1568. [PMID: 32748783 DOI: 10.4269/ajtmh.20-0505] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Human landing collections (HLCs) have been the standard method for the collection of black flies that serve as vectors for Onchocerca volvulus, the causative agent of onchocerciasis or river blindness. However, HLCs are inefficient and may expose collectors to vector-borne pathogens. The Esperanza window trap (EWT) has been shown to be a potential alternative to HLCs for the collection of Simulium damnosum, the principal vector of O. volvulus in Africa. To improve the performance of the EWT, sweat from individuals highly attractive or less attractive to S. damnosum sensu stricto was examined by gas chromatography and mass spectroscopy. Twelve compounds were identified which were solely present or present in increased amounts in the sweat of the highly attractive individuals. Two of these compounds (naphthalene and tert-hexadecyl mercaptan) were found to be attractive to S. damnosum s.s. in behavioral assays. Traps baited with these compounds outperformed those baited with the current standard bait of worn socks. Using these newly identified compounds as baits will make the EWT more efficient in collecting vector black flies and may enhance the potential utility of the EWT as a local vector control measure.
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Affiliation(s)
- Devon Cozart
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
| | - Thomson Lakwo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | - Canhui Liu
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
| | - Denis Loum
- Nwoya District Local Government, Nwoya, Uganda
| | - Benjamin Jacob
- College of Public Health, University of South Florida, Tampa, Florida
| | - Eddie W Cupp
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
| | - Thomas R Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
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20
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Tsapi EM, Todjom FG, Gamago GA, Pone JW, Teukeng FFD. Prevalence of onchocerciasis after seven years of continuous community-directed treatment with ivermectin in the Ntui health district, Centre region, Cameroon. Pan Afr Med J 2020; 36:180. [PMID: 32952824 PMCID: PMC7467880 DOI: 10.11604/pamj.2020.36.180.20765] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 02/23/2020] [Indexed: 11/18/2022] Open
Abstract
Introduction onchocerciasis is one of the major infectious diseases caused by Onchocerca volvulus. This parasite is responsible for chronic cutaneous and ocular diseases affecting more than 37 million people of whom 99% are in Africa. The study was conducted in the health district of Ntui from June to September 2016 to determine the prevalence of O. volvulus infection after seven years of massive administration of ivermectin. Methods two cutaneous snips were made at the iliac crests level in volunteers. These tissues were incubated in physiological saline water and were examined for parasitological investigations in the laboratory. Results a total of 310 participants were randomly selected, of whom 170 (54.8%) were women and 140 (45.1%) were men aged 6 to 83 years, thus giving a sex ratio of 1.2 in favour of women. After parasitological analysis, 26 participants had microfilaraemia, of whom 15 (10.7%) were men and 11 (6.4%) were women. The most infected age group was 16 to 26 years (12.5%). The highest infection rates were found among farmers (11%) and participants living in the village of Essougly (26.6%). No significant differences in prevalence values between the different groups were noted, whatever the parameter considered. Conclusion the prevalence of onchocerciasis in the health district of Ntui has declined from a hyperendemic to a hypoendemic state after seven years of massive administration of ivermectin. However, careful monitoring of onchocerciasis should be continued to prevent the area from returning to its original hyperendemicity.
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Affiliation(s)
| | - Françoise Guemgne Todjom
- Research Unit of Biology and Applied Ecology, Faculty of Science, University of Dschang, Dschang, Cameroon
| | - Guy-Armand Gamago
- Faculté des Sciences de la Santé, Université des Montagnes, Bangangté, Cameroon
| | - Josué Wabo Pone
- Faculté des Sciences de la Santé, Université des Montagnes, Bangangté, Cameroon
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21
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Romo ML. Novel evidence to motivate onchocerciasis elimination. THE LANCET. INFECTIOUS DISEASES 2020; 20:1223-1224. [PMID: 32598870 DOI: 10.1016/s1473-3099(20)30284-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 04/03/2020] [Indexed: 11/25/2022]
Affiliation(s)
- Matthew L Romo
- Institute for Implementation Science in Population Health and Graduate School of Public Health and Health Policy, City University of New York, NY 10027, USA; Program in Global Health and Development, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
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22
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Gumisiriza N, Kaiser C, Asaba G, Onen H, Mubiru F, Kisembo D, Siewe Fodjo JN, Colebunders R. Changes in epilepsy burden after onchocerciasis elimination in a hyperendemic focus of western Uganda: a comparison of two population-based, cross-sectional studies. THE LANCET. INFECTIOUS DISEASES 2020; 20:1315-1323. [PMID: 32598869 DOI: 10.1016/s1473-3099(20)30122-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Revised: 01/13/2020] [Accepted: 02/13/2020] [Indexed: 02/04/2023]
Abstract
BACKGROUND In 1994, prevalence and incidence of epilepsy were high in the Itwara onchocerciasis focus (western Uganda), and cases of nodding and Nakalanga syndrome were documented. Onchocerciasis transmission was interrupted successfully in 2001. 17 years later, we re-investigated the epilepsy burden in this area. METHODS From Dec 11 to Dec 15, 2018, a door-to-door survey was done in the three villages (Kabende Centre, Masongora South, and Rwesenene) with the highest epilepsy rates in 1994 to identify people with suspected epilepsy. Epilepsy diagnoses were confirmed by an interview and physical examination by a study clinician. The prevalence and incidence of epilepsy were measured using methods consistent with those used in 1994. Results from 2018 were compared with those from 1994. FINDINGS The overall crude prevalence of epilepsy in the study villages decreased from 3·0% (35 of 1169) in 1994 to 1·2% (27 of 2325) in 2018 (p=0·0002), with a concomitant decrease in the proportion of people with epilepsy with unknown cause (p=0·037). Between 1994 and 2018, the overall incidence of epilepsy decreased from 418 cases per 100 000 person-years (95% CI 265-626) to 73 new cases per 100 000 person-years (32-114; p<0·0001); this reduction was more pronounced for cases having the first seizure between ages 3 years and 18 years (p<0·0001). No new case of nodding or Nakalanga syndromes had occurred since the interruption of onchocerciasis transmission. INTERPRETATION Our findings support the existence of a negative association between onchocerciasis elimination and epilepsy burden in previously hyperendemic areas. Therefore, onchocerciasis elimination efforts should be intensified in endemic regions with a high prevalence of epilepsy, which might reduce the burden of epilepsy. FUNDING Flemish University Development Cooperation and the European Research Council.
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Affiliation(s)
| | | | - George Asaba
- Department of Pediatrics, Regional Referral Hospital, Fort Portal, Uganda
| | - Henry Onen
- Infectious Disease Institute, Makerere University, Kampala, Uganda
| | - Frank Mubiru
- Infectious Disease Institute, Makerere University, Kampala, Uganda
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23
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The Role of the Maridi Dam in Causing an Onchocerciasis-Associated Epilepsy Epidemic in Maridi, South Sudan: An Epidemiological, Sociological, and Entomological Study. Pathogens 2020; 9:pathogens9040315. [PMID: 32344586 PMCID: PMC7238195 DOI: 10.3390/pathogens9040315] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 04/22/2020] [Accepted: 04/23/2020] [Indexed: 11/24/2022] Open
Abstract
Background: An epilepsy prevalence of 4.4% was documented in onchocerciasis-endemic villages close to the Maridi River in South Sudan. We investigated the role of the Maridi dam in causing an onchocerciasis-associated epilepsy epidemic in these villages. Methods: Affected communities were visited in November 2019 to conduct focus group discussions with village elders and assess the OV16 seroprevalence in 3- to 9-year-old children. Entomological assessments to map blackfly breeding sites and determine biting rates around the Maridi River were conducted. Historical data regarding various activities at the Maridi dam were obtained from the administrative authorities. Results: The Maridi dam was constructed in 1954–1955. Village elders reported an increasing number of children developing epilepsy, including nodding syndrome, from the early 1990s. Kazana 2 (the village closest to the dam; epilepsy prevalence 11.9%) had the highest OV16 seroprevalence: 40.0% among children 3–6 years old and 66.7% among children 7–9 years old. The Maridi dam spillway was found to be the only Simulium damnosum breeding site along the river, with biting rates reaching 202 flies/man/h. Conclusion: Onchocerciasis transmission rates are high in Maridi. Suitable breeding conditions at the Maridi dam, coupled with suboptimal onchocerciasis control measures, have probably played a major role in causing an epilepsy (including nodding syndrome) epidemic in the Maridi area.
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24
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Michael E, Smith ME, Singh BK, Katabarwa MN, Byamukama E, Habomugisha P, Lakwo T, Tukahebwa E, Richards FO. Data-driven modelling and spatial complexity supports heterogeneity-based integrative management for eliminating Simulium neavei-transmitted river blindness. Sci Rep 2020; 10:4235. [PMID: 32144362 PMCID: PMC7060237 DOI: 10.1038/s41598-020-61194-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 02/24/2020] [Indexed: 11/28/2022] Open
Abstract
Concern is emerging regarding the challenges posed by spatial complexity for modelling and managing the area-wide elimination of parasitic infections. While this has led to calls for applying heterogeneity-based approaches for addressing this complexity, questions related to spatial scale, the discovery of locally-relevant models, and its interaction with options for interrupting parasite transmission remain to be resolved. We used a data-driven modelling framework applied to infection data gathered from different monitoring sites to investigate these questions in the context of understanding the transmission dynamics and efforts to eliminate Simulium neavei- transmitted onchocerciasis, a macroparasitic disease that causes river blindness in Western Uganda and other regions of Africa. We demonstrate that our Bayesian-based data-model assimilation technique is able to discover onchocerciasis models that reflect local transmission conditions reliably. Key management variables such as infection breakpoints and required durations of drug interventions for achieving elimination varied spatially due to site-specific parameter constraining; however, this spatial effect was found to operate at the larger focus level, although intriguingly including vector control overcame this variability. These results show that data-driven modelling based on spatial datasets and model-data fusing methodologies will be critical to identifying both the scale-dependent models and heterogeneity-based options required for supporting the successful elimination of S. neavei-borne onchocerciasis.
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Affiliation(s)
- Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA.
| | - Morgan E Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Brajendra K Singh
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, 46556, USA
| | - Moses N Katabarwa
- The Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA, 30307, USA
| | - Edson Byamukama
- The Carter Center, Uganda, 15 Bombo Road, P.O. Box, 12027, Kampala, Uganda
| | - Peace Habomugisha
- The Carter Center, Uganda, 15 Bombo Road, P.O. Box, 12027, Kampala, Uganda
| | - Thomson Lakwo
- Vector Control Division, Ministry of Health, 15 Bombo Road, P.O. Box, 1661, Kampala, Uganda
| | - Edridah Tukahebwa
- Vector Control Division, Ministry of Health, 15 Bombo Road, P.O. Box, 1661, Kampala, Uganda
| | - Frank O Richards
- The Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA, 30307, USA
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25
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Prevalence and incidence of nodding syndrome and other forms of epilepsy in onchocerciasis-endemic areas in northern Uganda after the implementation of onchocerciasis control measures. Infect Dis Poverty 2020; 9:12. [PMID: 32114979 PMCID: PMC7050130 DOI: 10.1186/s40249-020-0628-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 01/14/2020] [Indexed: 12/20/2022] Open
Abstract
Background Around 2007, a nodding syndrome (NS) epidemic appeared in onchocerciasis-endemic districts of northern Uganda, where ivermectin mass distribution had never been implemented. This study evaluated the effect of community-directed treatment with ivermectin (CDTI) and ground larviciding of rivers initiated after 2009 and 2012 respectively, on the epidemiology of NS and other forms of epilepsy (OFE) in some districts of northern Uganda. Methods In 2012, a population-based community survey of NS/epilepsy was carried out by the Ugandan Ministry of Health in Kitgum and Pader districts. In August 2017, we conducted a new survey in selected villages of these districts and compared our findings with the 2012 data. In addition, two villages in Moyo district (where CDTI was ongoing since 1993) served as comparative onchocerciasis-endemic sites in which larviciding had never been implemented. The comparison between 2012 and 2017 prevalence and cumulative incidence were done using the Fisher’s and Pearson’s Chi-square tests at 95% level of significance. Results A total of 2138 individuals in 390 households were interviewed. In the selected villages of Kitgum and Pader, there was no significant decrease in prevalence of NS and OFE between 2012 and 2017. However, the cumulative incidence of all forms of epilepsy decreased from 1165 to 130 per 100 000 persons per year (P = 0.002); that of NS decreased from 490 to 43 per 100 000 persons per year (P = 0.037); and for OFE from 675 to 87 per 100 000 persons per year (P = 0.024). The median age of affected persons (NS and OFE) shifted from 13.5 (IQR: 11.0–15.0) years in 2012 to 18.0 (IQR: 15.0–20.3) years in 2017; P < 0.001. The age-standardized prevalence of OFE in Moyo in 2017 was 4.6%, similar to 4.5% in Kitgum and Pader. Conclusions Our findings support the growing evidence of a relationship between infection by Onchocerca volvulus and some types of childhood epilepsy, and suggest that a combination of bi-annual mass distribution of ivermectin and ground larviciding of rivers is an effective strategy to prevent NS and OFE in onchocerciasis-hyperendemic areas.
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26
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Katabarwa MN, Zarroug IMA, Negussu N, Aziz NM, Tadesse Z, Elmubark WA, Shumo Z, Meribo K, Kamal H, Mohammed A, Bitew Y, Seid T, Bekele F, Yilak A, Endeshaw T, Hassen M, Tillahun A, Samuel F, Birhanu H, Asmare T, Boakye D, Feleke SM, Unnasch T, Post R, Higazi T, Griswold E, Mackenzie C, Richards F. The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa. PLoS Negl Trop Dis 2020; 14:e0007830. [PMID: 32027648 PMCID: PMC7004312 DOI: 10.1371/journal.pntd.0007830] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 10/05/2019] [Indexed: 11/18/2022] Open
Abstract
Background Onchocerciasis transmission across international borders is not uncommon, yet a coordinated cross border stops mass drug administration (MDA) decision has not been documented. Methods/Principle findings The Galabat-Metema focus involves neighboring districts on the border between Sudan and Ethiopia. Mass drug administration (MDA) was provided once and subsequently twice per year in this focus, with twice-per-year beginning in Ethiopia’s Metema subfocus in 2016 and in the Sudan’s Galabat subfocus in 2008. Ov16 ELISA-based serosurveys were conducted in 6072 children under 10 years of age in the Metema subfocus in 2014, and 3931 in the Galabat in 2015. Between 2014 and 2016, a total of 27,583 vector Simulium damnosum flies from Metema and 9,148 flies from Galabat were tested by pool screen PCR for Onchocerca volvulus O-150 DNA. Only 8 children were Ov16 seropositive (all in the Metema subfocus); all were negative by skin snip PCR. The upper limit of the 95% confidence interval (UCL) for Ov16 seropositive was <0.1% for the overall focus and 0.14 positive fly heads per 2000 (UCL = 0.39/2000). However, an entomological ‘hotspot’ was detected on the Wudi Gemzu river in Metema district. The hotspot was confirmed when 4 more positive fly pools were found on repeat testing in 2017 (1.04 L3/2000 flies (UCL = 2.26/2000). Information exchange between the two countries led to stopping MDA in a coordinated fashion in 2018, with the exception of the hotspot at Wudi Gemzu, where MDA with ivermectin was increased to every three months to hasten interruption of transmission. Conclusion Coordinated stop MDA decisions were made by Sudan and Ethiopia based on data satisfying the World Health Organization’s criteria for interruption of onchocerciasis transmission. Definitions of entomological ‘hotspots’ and buffer zones around the focus are proposed. Onchocerciasis is a vector-borne tropical disease caused by the parasitc worm, Onchocerca volvulus. The vector is Simulium flies that breed in fast flowing rivers and streams. The infection can cause skin disease and loss of vision, giving risk to the common name of ‘river blindness’ for the condition. Ivermectin (Mectizan) mass drug administration (MDA) given at high coverage for many years can interrupt transmission such that MDA can eventually be stopped. The present paper provides highlights of onchocerciasis transmission interruption in the first known coordinated international cross border focus with ivermectin MDA program in Africa, where 99% of the global onchocerciasis burden exists. This focus known as Galabat-Metema is shared between Ethiopia and Sudan, both of which have established a nationwide policy for elimination of onchocerciasis. The paper provides the history of MDA in the border area and the results leading a coordinated end to MDA in the focus in 2017.
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Affiliation(s)
- Moses N. Katabarwa
- Health Programs, The Carter Center, Atlanta, Georgia, United States of America
- * E-mail:
| | | | | | | | | | | | | | - Kadu Meribo
- Federal Ministry of Health, Addis Ababa, Ethiopia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | - Thomas Unnasch
- College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Rory Post
- London School of Hygiene & Tropical Medicine, London, United Kingdom, United Kingdom
| | - Tarig Higazi
- Department of Biological Sciences, Ohio University, Zanesville, Ohio, United States of America
| | - Emily Griswold
- Health Programs, The Carter Center, Atlanta, Georgia, United States of America
| | - Charles Mackenzie
- NTD Support Center, Task Force for Global Health, Atlanta, Georgia, United States of America
| | - Frank Richards
- Health Programs, The Carter Center, Atlanta, Georgia, United States of America
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27
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Smith ME, Bilal S, Lakwo TL, Habomugisha P, Tukahebwa E, Byamukama E, Katabarwa MN, Richards FO, Cupp EW, Unnasch TR, Michael E. Accelerating river blindness elimination by supplementing MDA with a vegetation "slash and clear" vector control strategy: a data-driven modeling analysis. Sci Rep 2019; 9:15274. [PMID: 31649285 PMCID: PMC6813336 DOI: 10.1038/s41598-019-51835-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 10/09/2019] [Indexed: 01/08/2023] Open
Abstract
Attention is increasingly focusing on how best to accelerate progress toward meeting the WHO's 2030 goals for neglected tropical diseases (NTDs). For river blindness, a major NTD targeted for elimination, there is a long history of using vector control to suppress transmission, but traditional larvicide-based approaches are limited in their utility. One innovative and sustainable approach, "slash and clear", involves clearing vegetation from breeding areas, and recent field trials indicate that this technique very effectively reduces the biting density of Simulium damnosum s.s. In this study, we use a Bayesian data-driven mathematical modeling approach to investigate the potential impact of this intervention on human onchocerciasis infection. We developed a novel "slash and clear" model describing the effect of the intervention on seasonal black fly biting rates and coupled this with our population dynamics model of Onchocerca volvulus transmission. Our results indicate that supplementing annual drug treatments with "slash and clear" can significantly accelerate the achievement of onchocerciasis elimination. The efficacy of the intervention is not very sensitive to the timing of implementation, and the impact is meaningful even if vegetation is cleared only once per year. As such, this community-driven technique will represent an important option for achieving and sustaining O. volvulus elimination.
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Affiliation(s)
- Morgan E Smith
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Shakir Bilal
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA
| | - Thomson L Lakwo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | | | | | | | - Eddie W Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, USA
| | - Thomas R Unnasch
- Department of Global Health, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Edwin Michael
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
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Richards FO, Nwoke BEB, Zarroug I, Tukahebwa E, Negussu N, Higazi TB, Oguttu D, Tadesse Z, Miri E, Aziz N, Habomugisha P, Katabarwa M. The positive influence the Onchocerciasis Elimination Program for the Americas has had on Africa programs. Infect Dis Poverty 2019; 8:52. [PMID: 31303175 PMCID: PMC6628490 DOI: 10.1186/s40249-019-0558-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 05/28/2019] [Indexed: 01/28/2023] Open
Abstract
A recent article “Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes” in Infectious Diseases of Poverty claimed that undue influence on African programs by concepts developed by the Onchocerciasis Elimination Program of the Americas (OEPA) is detrimental to stopping mass drug administration (MDA) in Africa. This claim is made despite a record year for MDA stoppage in four African countries of > 3.5 million treatments in 2018, far exceeding any past OEPA or African Program for Onchocerciasis Control (APOC) stop MDA success.
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Affiliation(s)
- Frank O Richards
- The Carter Center, One Copenhill Avenue, 453 Freedom Parkway, Atlanta, GA, 30307, USA.
| | - B E B Nwoke
- Imo State University Owerri, PMB 2000, Owerri, Nigeria
| | - Isam Zarroug
- Sudan Ministry of Health, P.O. Box 303, Khartoum, Sudan
| | - Edridah Tukahebwa
- Uganda Ministry of Health, 15 Bombo Rd., P. O. Box 1661, Kampala, Uganda
| | - Nebiyu Negussu
- Ethiopia Federal Ministry of Health, P. O. Box 1234, Addis Ababa, Ethiopia
| | - T B Higazi
- Ohio University, 1425 Newark Rd, Zanesville, OH, 43701, USA
| | - David Oguttu
- Uganda Ministry of Health, 15 Bombo Rd., P. O. Box 1661, Kampala, Uganda
| | - Zerihun Tadesse
- The Carter Center-Ethiopia, P. O. Box 13373, Bole K. K. Kebele 05, Addis Ababa, Ethiopia
| | - Emmanuel Miri
- The Carter Center-Nigeria, No. 1 Jeka Kadima St, Jos, Plateau State, Nigeria
| | - Nabil Aziz
- The Carter Center-Sudan, P. O. Box 48, Khartoum, Sudan
| | | | - Moses Katabarwa
- The Carter Center, One Copenhill Avenue, 453 Freedom Parkway, Atlanta, GA, 30307, USA
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Gebrezgabiher G, Mekonnen Z, Yewhalaw D, Hailu A. Reaching the last mile: main challenges relating to and recommendations to accelerate onchocerciasis elimination in Africa. Infect Dis Poverty 2019; 8:60. [PMID: 31269966 PMCID: PMC6609392 DOI: 10.1186/s40249-019-0567-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 06/10/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Onchocerciasis (river blindness), caused by the filarial worm species Onchocerca volvulus, is a serious vector-borne neglected tropical disease (NTD) of public health and socioeconomic concern. It is transmitted through the bite of black flies of the genus Simulium, and manifested in dermal and ocular lesions. Ninety-nine percent of the total global risk and burden of onchocerciasis is in Africa. This scoping review examines the key challenges related to the elimination of onchocerciasis by 2020-2025 in Africa, and proposes recommendations to overcome the challenges and accelerate disease elimination. To find relevant articles published in peer-reviewed journals, a search of PubMed and Google Scholar databases was carried out. MAIN TEXT Rigorous regional interventions carried out to control and eliminate onchocerciasis in the past four decades in Africa have been effective in bringing the disease burden under control; it is currently not a public health problem in most endemic areas. Notably, transmission of the parasite is interrupted in some hyperendemic localities. Recently, there has been a policy shift from control to complete disease elimination by 2020 in selected countries and by 2025 in the majority of endemic African countries. The WHO has published guidelines for stopping mass drug administration (MDA) and verifying the interruption of transmission and elimination of human onchocerciasis. Therefore, countries have revised their plans, established a goal of disease elimination in line with an evidence based decision to stop MDA and verify elimination, and incorporated it into their NTDs national master plans. Nevertheless, challenges remain pertaining to the elimination of onchocerciasis in Africa. The challenge we review in this paper are: incomplete elimination mapping of all transmission zones, co-endemicity of onchocerciasis and loiasis, possible emergence of ivermectin resistance, uncoordinated cross-border elimination efforts, conflict and civil unrest, suboptimal program implementation, and technical and financial challenges. This paper also proposes recommendations to overcome the challenges and accelerate disease elimination. These are: a need for complete disease elimination mapping, a need for collaborative elimination activities between national programs, a need for a different drug distribution approach in conflict-affected areas, a need for routine monitoring and evaluation of MDA programs, a need for implementing alternative treatment strategies (ATSs) in areas with elimination anticipated beyond 2025, and a need for strong partnerships and continued funding. CONCLUSIONS National programs need to regularly monitor and evaluate the performance and progress of their interventions, while envisaging the complete elimination of onchocerciasis from their territory. Factors hindering the targeted goal of interruption of parasite transmission need to be identified and remedial actions should be taken. If possible and appropriate, ATSs need to be implemented to accelerate disease elimination by 2025.
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Affiliation(s)
- Gebremedhin Gebrezgabiher
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- College of Veterinary Medicine, Samara University, Samara, Ethiopia
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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Irani J, Rujumba J, Mwaka AD, Arach J, Lanyuru D, Idro R, Gerrets R, Grietens KP, O’Neill S. "Those who died are the ones that are cured". Walking the political tightrope of Nodding Syndrome in northern Uganda: Emerging challenges for research and policy. PLoS Negl Trop Dis 2019; 13:e0007344. [PMID: 31220081 PMCID: PMC6605670 DOI: 10.1371/journal.pntd.0007344] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Revised: 07/02/2019] [Accepted: 03/28/2019] [Indexed: 11/19/2022] Open
Abstract
Background Nodding Syndrome was first reported from Tanzania in the 1960s but appeared as an epidemic in Northern Uganda in the 1990s during the LRA civil war. It is characterized by repetitive head nodding, often followed by other types of seizures, developmental retardation and growth faltering with onset occurring in children aged 5–15 years. More than 50 years after the first reports, the aetiology remains unknown and there is still no cure. The recent hypothesis that Nodding Syndrome is caused by onchocerciasis also increases the relevance of onchocerciasis control. Northern Uganda, with its unique socio-political history, adds challenges to the prevention and treatment for Nodding Syndrome. This article aims to show how and why Nodding Syndrome has been politicised in Uganda; how this politicisation has affected health interventions including research and dissemination; and, the possible implications this can have for disease prevention and treatment. Methodology Ethnographic research methods were used triangulating in-depth interviews, focus group discussions, informal conversations and participant observation, for an understanding of the various stakeholders’ perceptions of Nodding Syndrome and how these perceptions impact future interventions for prevention, treatment and disease control. Principal findings Distrust towards the government was a sentiment that had developed in Northern Uganda over several decades of war and was particularly linked to the political control and ethnic divisions between the north and south. This coincided with the sudden appearance of Nodding Syndrome, an unknown epidemic disease of which the cause could not be clearly identified and optimal treatment had not clearly been established. Additionally, the dissemination of the inconclusive results of research conducted in the area lacked sufficient community involvement which further fueled this political distrust. Disease perceptions revolved around rumours that the entire Acholi ethnic group of the north would be annihilated, or that international researchers were making money by stealing study samples. This discouraged some community members from participating in research or from accepting the mass drug administration of ivermectin for prevention and treatment of onchocerciasis. Such rumour and distrust led to suspicions concerning the integrity of the disseminated results, which may negatively impact future disease management and control interventions. Conclusions and recommendations Trust must be built up gradually through transparency and by de-politicising interventions. This can be done by engaging the community at regular intervals during research and data collection and the dissemination of results in addition to involvement during service delivery for prevention and treatment. Maintaining a regular feedback loop with the community will help control rumours, build trust, and improve the preparations for adequate dissemination. Nodding Syndrome, a form of epilepsy that occurs in onchocerciasis-endemic areas has affected about 3000 children in Northern Uganda where the epidemic emerged at the time of the civil war. Although an association with onchocerciasis has been established, the disease etiology has not yet been identified. In conjunction with the area’s history of war, political conflict and ethnic divides, many affected people were suspicious of government health interventions and scientific studies. Furthermore, ambiguities around the disease etiology leaves room for several interpretations, which in addition to distrust leads to rumours, that may hinder future interventions. In view of improving adherence to health interventions, this article explains the socio-political nature of Nodding Syndrome in Northern Uganda. We show how and why this disease has been politicised in Uganda; how this politicisation has affected research and dissemination; and, the implications this has for disease control. The insights presented will be critical for reducing resistance to research, to treatment and to the dissemination of knowledge which is necessary for the prevention and control of Nodding Syndrome and onchocerciasis in Northern Uganda.
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Affiliation(s)
- Julia Irani
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
- * E-mail:
| | - Joseph Rujumba
- Department of Pediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Amos Deogratius Mwaka
- Department of Medicine, School of Medicine, College of Health Sciences, Makerere University, Kampala, Uganda
- The Ugandan Ministry of Health, Kampala, Uganda
| | - Jesca Arach
- Department of Pediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Denis Lanyuru
- Department of Pediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
| | - Richard Idro
- Department of Pediatrics and Child Health, College of Health Sciences, Makerere University, Kampala, Uganda
- The Ugandan Ministry of Health, Kampala, Uganda
| | - Rene Gerrets
- The Amsterdam Institute for Social Science Research, University of Amsterdam, Amsterdam, Netherlands
| | | | - Sarah O’Neill
- Department of Public Health, Institute of Tropical Medicine, Antwerp, Belgium
- CRISS, Ecole de Santé Publique and LAMC, Faculté de Philosophie et Sciences Sociales, Université Libre de Bruxelles, Brussels, Belgium
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Wangala B, Gantin RG, Voßberg PS, Vovor A, Poutouli WP, Komlan K, Banla M, Köhler C, Soboslay PT. Inflammatory and regulatory CCL and CXCL chemokine and cytokine cellular responses in patients with patent Mansonella perstans filariasis. Clin Exp Immunol 2019; 196:111-122. [PMID: 30561772 DOI: 10.1111/cei.13251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2018] [Indexed: 12/17/2022] Open
Abstract
Mansonella perstans (Mp) filariasis is present in large populations in sub-Saharan Africa, and to what extent patent Mp infection modulates the expression of immunity in patients, notably their cellular cytokine and chemokine response profile, remains not well known. We studied the spontaneous and inducible cellular production of chemokines (C-X-C motif) ligand 9 (CXCL9) [monokine induced by interferon (IFN)-γ (MIG)], CXCL-10 [inducible protein (IP)-10], chemokine (C-C motif) ligand 24 (CCL24) (eotaxin-2), CCL22 [macrophage-derived chemokine (MDC)], CCL13 [monocyte chemotactic protein-4 (MCP-4)], CCL18 [pulmonary and activation-regulated chemokine (PARC)], CCL17 [thymus- and activation-regulated chemokine (TARC)] and interleukin (IL)-27 in mansonelliasis patients (Mp-PAT) and mansonelliasis-free controls (CTRL). Freshly isolated peripheral mononuclear blood cells (PBMC) were stimulated with helminth, protozoan and bacterial antigens and mitogen [phytohaemagglutinin (PHA)]. PBMC from Mp-PAT produced spontaneously (without antigen stimulation) significantly higher levels of eotaxin-2, IL-27, IL-8, MCP-4 and MDC than cells from CTRL, while IFN-γ-IP-10 was lower in Mp-PAT. Helminth antigens activated IL-27 and MCP-4 only in CTRL, while Ascaris antigen, Onchocerca antigen, Schistosoma antigen, Entamoeba antigen, Streptococcus antigen, Mycobacteria antigen and PHA stimulated MIG release in CTRL and Mp-PAT. Notably, Entamoeba antigen and PHA strongly depressed (P < 0·0001) eotaxin-2 (CCL24) production in both study groups. Multiple regression analyses disclosed in Mp-PAT and CTRL dissimilar cellular chemokine and cytokine production levels being higher in Mp-PAT for CCL24, IL-27, IL-8, MCP-4, MDC and PARC (for all P < 0·0001), at baseline (P < 0·0001), in response to Entamoeba histolytica strain HM1 antigen (EhAg) (P < 0·0001), Onchocerca volvulus adult worm-derived antigen (OvAg) (P = 0·005), PHA (P < 0·0001) and purified protein derivative (PPD) (P < 0·0001) stimulation. In Mp-PAT with hookworm co-infection, the cellular chemokine production of CXCL10 (IP-10) was diminished. In summary, the chemokine and cytokine responses in Mp-PAT were in general not depressed, PBMC from Mp-PAT produced spontaneously and selectively inducible inflammatory and regulatory chemokines and cytokines at higher levels than CTRL and such diverse and distinctive reactivity supports that patent M. perstans infection will not polarize innate and adaptive cellular immune responsiveness in patients.
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Affiliation(s)
- B Wangala
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo
| | - R G Gantin
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - P S Voßberg
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - A Vovor
- Centre Hospitalier Universitaire Sylvanus Olympio, Laboratory for Hematology, Université de Lomé, Togo
| | - W P Poutouli
- Faculté de Sciences, Université de Lomé, Lomé, Togo
| | - K Komlan
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo
| | - M Banla
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Centre Hospitalier Universitaire Campus, Université de Lomé, Togo
| | - C Köhler
- Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - P T Soboslay
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
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Hotterbeekx A, Namale Ssonko V, Oyet W, Lakwo T, Idro R. Neurological manifestations in Onchocerca volvulus infection: A review. Brain Res Bull 2018; 145:39-44. [PMID: 30458251 PMCID: PMC6382410 DOI: 10.1016/j.brainresbull.2018.08.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 08/22/2018] [Accepted: 08/25/2018] [Indexed: 11/17/2022]
Abstract
Human onchocerciasis, caused by infection by the filarial nematode Onchocerca volvulus, is a major neglected public health problem that affects millions of people in the endemic regions of sub-Saharan Africa and Latin America. Onchocerciasis is known to be associated with skin and eye disease and more recently, neurological features have been recognized as a major manifestation. Especially the latter poses a severe burden on affected individuals and their families. Although definite studies are awaited, preliminary evidence suggests that neurological disease may include the nodding syndrome, Nakalanga syndrome and epilepsy but to date, the exact pathophysiological mechanisms remain unclear. Currently, the only way to prevent Onchocera volvulus associated disease is through interventions that target the elimination of onchocerciasis through community distribution of ivermectin and larviciding the breeding sites of the Similium or blackfly vector in rivers. In this review, we discuss the epidemiology, potential pathological mechanisms as well as prevention and treatment strategies of onchocerciasis, focusing on the neurological disease.
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Affiliation(s)
- An Hotterbeekx
- University of Antwerp, Global Health Institute, Antwerp, Belgium
| | | | | | - Thomson Lakwo
- Ministry of Health, Division of Vector Control, Kampala, Uganda
| | - Richard Idro
- Makerere University College of Health Sciences, Kampala, Uganda; Centre for Tropical Neuroscience, Kampala, Uganda; University of Oxford, Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford, UK.
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Kaiser C, Asaba G, Rubaale T, Tukesiga E, Kipp W. Onchocerciasis-Associated Epilepsy with Head Nodding Seizures-Nodding Syndrome: A Case Series of 15 Patients from Western Uganda, 1994. Am J Trop Med Hyg 2018; 99:1211-1218. [PMID: 30226148 PMCID: PMC6221207 DOI: 10.4269/ajtmh.18-0511] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 08/05/2018] [Indexed: 11/07/2022] Open
Abstract
Nodding syndrome (NS) is an encephalopathy characterized by the core symptom of epileptic head nodding seizures, affecting children at the age between 3 and 18 years in distinct areas of tropical Africa. A consistent correlation with onchocerciasis was found, but so far, the causation of NS has not been fully clarified. With a systematic analysis of features of a cohort of epilepsy patients examined in the Itwara onchocerciasis focus of western Uganda in 1994, we provide evidence that NS actually occurred in this area at this time, and we demonstrate a correlation between prevalence of NS and that of onchocerciasis in different villages. Following the elimination of onchocerciasis by community-directed treatment with ivermectin and ground larviciding, our data provide a baseline to examine the question whether NS will disappear once its putative cause has been removed.
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Affiliation(s)
- Christoph Kaiser
- Basic Health Services Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - George Asaba
- Basic Health Services Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Tom Rubaale
- Basic Health Services Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Ephraim Tukesiga
- Basic Health Services Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
| | - Walter Kipp
- Basic Health Services Kabarole and Bundibugyo Districts, Fort Portal, Uganda; Vector Control Unit, Ministry of Health, Fort Portal, Uganda; Department of Public Health Sciences, University of Alberta, Edmonton, Canada
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Murdoch ME. Onchodermatitis: Where Are We Now? Trop Med Infect Dis 2018; 3:E94. [PMID: 30274490 PMCID: PMC6160948 DOI: 10.3390/tropicalmed3030094] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Revised: 08/27/2018] [Accepted: 08/28/2018] [Indexed: 02/07/2023] Open
Abstract
Onchocerciasis causes debilitating pruritus and rashes as well as visual impairment and blindness. Prior to control measures, eye disease was particularly prominent in savanna areas of sub-Saharan Africa whilst skin disease was more common across rainforest regions of tropical Africa. Mass drug distribution with ivermectin is changing the global scene of onchocerciasis. There has been successful progressive elimination in Central and Southern American countries and the World Health Organization has set a target for elimination in Africa of 2025. This literature review was conducted to examine progress regarding onchocercal skin disease. PubMed searches were performed using keywords 'onchocerciasis', 'onchodermatitis' and 'onchocercal skin disease' over the past eight years. Articles in English, or with an English abstract, were assessed for relevance, including any pertinent references within the articles. Recent progress in awareness of, understanding and treatment of onchocercal skin disease is reviewed with particular emphasis on publications within the past five years. The global burden of onchodermatitis is progressively reducing and is no longer seen in children in many formerly endemic foci.
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Affiliation(s)
- Michele E Murdoch
- Department of Dermatology, West Herts Hospitals NHS Trust, Vicarage Road, Watford, Hertfordshire WD18 0HB, UK.
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Elhassan E, Zhang Y, Bush S, Molyneux D, Kollmann MKH, Sodahlon Y, Richards F. The role of the NGDO Coordination Group for the Elimination of Onchocerciasis. Int Health 2018; 10:i97-i101. [PMID: 29471339 DOI: 10.1093/inthealth/ihx050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/30/2017] [Indexed: 11/14/2022] Open
Abstract
The NGDO Coordination Group for the Control of Onchocerciasis was launched in 1992, and with the paradigm shift from control of disease to elimination of onchocerciasis transmission, the Group shifted its orientation to that new paradigm in 2013. It also changed its name, replacing 'control' with 'elimination.' In doing so, the Group has repositioned itself to build on the successes of the past to finish the job it began over 25 years ago.
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Affiliation(s)
| | | | | | - David Molyneux
- Liverpool School of Tropical Medicine and Hygiene, Liverpool, UK
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