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Guiguemde KT, Sawadogo PM, Zida A, Kima A, Bougma RW, Serme M, Sangaré I, Bougouma C, Bamba S. Situation of onchocerciasis transmission in 2020 in the Cascades region of Burkina Faso. Parasitol Int 2024; 98:102822. [PMID: 37940035 DOI: 10.1016/j.parint.2023.102822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2023] [Revised: 10/27/2023] [Accepted: 11/05/2023] [Indexed: 11/10/2023]
Abstract
Faced with the focal resurgence of onchocerciasis reported since 2004 in the South-West of Burkina Faso, the Neglected Tropical Diseases Control Program adopted a resumption of biannual community-directed treatment with ivermectin, since 2011 in the Cascades region and since 2013 in the South West region. The objective of this study was to assess the situation of onchocerciasis transmission in the Cascades region, nine years after the resumption of mass drug administration. This cross-sectional and descriptive survey concerned people over 5. The traditional method of skin snip on both iliac crests was performed for the parasitological diagnosis of onchocerciasis. The Ov-16 serological test was carried out in children aged 5 to 9 years. In 22 surveyed villages, the overall prevalence of microfilariae was 0.11% and below the tolerable threshold of 5%. It was less than 5% in all the villages (n = 22), less than 1% in 21 villages (99%) and zero in 19 villages (86.36%). The community microfilarial loads varied from 0.01 to 0.05 mf/b. Out of 946 children tested for OV-16, only one 9-year-old was positive and whose skin snip examination was negative. All the positive cases came from endemical areas in Côte d'Ivoire. Population migration is a risk factor for introducing the parasite into Burkina Faso; it also is risk factor for the effective elimination of onchocerciasis which requires the joint development of a control strategy between neighboring countries.
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Affiliation(s)
| | | | - Adama Zida
- Laboratory of Parasitology-Mycology, UFR SDS, Joseph Ki-Zerbo University, Ouagadougou, Burkina Faso
| | - Apollinaire Kima
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou, Burkina Faso
| | - Roland Windtaré Bougma
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou, Burkina Faso
| | - Mamadou Serme
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou, Burkina Faso
| | - Ibrahim Sangaré
- Department of Parasitology-Mycology, Nazi Boni University, Bobo Dioulasso, Burkina Faso
| | - Clarisse Bougouma
- National Program for the Control of Neglected Tropical Diseases, Ouagadougou, Burkina Faso
| | - Sanata Bamba
- Department of Parasitology-Mycology, Nazi Boni University, Bobo Dioulasso, Burkina Faso
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2
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Buckner M, Montaño M, Vanegas I. Integrating Traditional Midwives into the State Health System: A Critical Case Study from Chiapas, Mexico. Med Anthropol 2022; 41:824-838. [PMID: 36069564 DOI: 10.1080/01459740.2022.2113395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Efforts to integrate traditional midwives into state health systems have not succeeded in reducing perinatal mortality, but have nevertheless continued in many countries, including Mexico. The authors used ethnographic methods to examine an NGO's efforts to integrate traditional midwives into the state health system in the Sierra Madre region of Chiapas, Mexico. We found that most of the traditional midwives in the study area have little to gain by such integration, and ask whether it is possible, practical, and ethical to integrate traditional midwives into health institutions until and unless such policy is grounded in local realities.
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Affiliation(s)
- Margaret Buckner
- Department of Sociology and Anthropology, Missouri State University, Springfield, MO, USA
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3
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Dusabimana A, Siewe Fodjo JN, Ndahura MM, Mmbando BP, Jada SR, Boven A, De Smet E, Ukety T, Njamnshi AK, Laudisoit A, Abrams S, Colebunders R. Surveillance for Onchocerciasis-Associated Epilepsy and OV16 IgG4 Testing of Children 6-10 Years Old Should Be Used to Identify Areas Where Onchocerciasis Elimination Programs Need Strengthening. Pathogens 2022; 11:281. [PMID: 35335605 PMCID: PMC8949980 DOI: 10.3390/pathogens11030281] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 02/17/2022] [Accepted: 02/18/2022] [Indexed: 01/27/2023] Open
Abstract
To eliminate onchocerciasis-associated morbidity, it is important to identify areas where there is still high ongoing Onchocerca volvulus transmission. Between 2015 and 2021, door-to-door surveys were conducted in onchocerciasis-endemic villages in Cameroon, the Democratic Republic of Congo (DRC), Nigeria, South Sudan, and Tanzania to determine epilepsy prevalence and incidence, type of epilepsy and ivermectin therapeutic coverage. Moreover, children aged between six and 10 years were tested for anti-Onchocerca antibodies using the Ov16 IgG4 rapid diagnostic test (RDT). A mixed-effect binary logistic regression analysis was used to assess significantly associated variables of Ov16 antibody seroprevalence. A high prevalence and incidence of epilepsy was found to be associated with a high Ov16 antibody seroprevalence among 6-10-year-old children, except in the Logo health zone, DRC. The low Ov16 antibody seroprevalence among young children in the Logo health zone, despite a high prevalence of epilepsy, may be explained by a recent decrease in O. volvulus transmission because of a decline in the Simulium vector population as a result of deforestation. In the Central African Republic, a new focus of O. volvulus transmission was detected based on the high Ov16 IgG4 seropositivity among children and the detecting of nodding syndrome cases, a phenotypic form of onchocerciasis-associated epilepsy (OAE). In conclusion, Ov16 IgG4 RDT testing of 6-10-year-old children is a cheap and rapid method to determine the level of ongoing O. volvulus transmission and to assess, together with surveillance for OAE, the performance of onchocerciasis elimination programs.
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Affiliation(s)
- Alfred Dusabimana
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
| | - Joseph Nelson Siewe Fodjo
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
- Brain Research Africa Initiative (BRAIN), Yaoundé P.O. Box 25625, Cameroon;
| | - Michel Mandro Ndahura
- Provincial Health Division Ituri, Ministry of Health, Bunia P.O. Box 57, Ituri, Democratic Republic of the Congo;
| | - Bruno P. Mmbando
- National Institute for Medical Research, Tanga Centre, Tanga P.O. Box 5004, Tanzania;
| | | | - Annelies Boven
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
| | - Eric De Smet
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
| | - Tony Ukety
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Ituri, Democratic Republic of the Congo;
| | - Alfred K. Njamnshi
- Brain Research Africa Initiative (BRAIN), Yaoundé P.O. Box 25625, Cameroon;
- Neuroscience Laboratory, Faculty of Medicine and Biomedical Sciences, The University of Yaoundé I, Yaoundé P.O. Box 25625, Cameroon
- Neurology Department, Yaoundé Central Hospital, Yaoundé P.O. Box 25625, Cameroon
| | - Anne Laudisoit
- EcoHealth Alliance, 520 8th Ave Ste. 1200, New York, NY 10018, USA;
- Evolutionary Ecology Group (EVECO), University of Antwerp, Universiteitsplein 1, 2610 Antwerp, Belgium
| | - Steven Abrams
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
- Interuniversity Institute for Biostatistics and statistical Bioinformatics, Data Science Institute, UHasselt, Agoralaan Building D, 3590 Diepenbeek, Belgium
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.); (A.B.); (E.D.S.); (S.A.)
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4
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Efon Ekangouo A, Nana Djeunga HC, Sempere G, Kamgno J, Njiokou F, Moundipa Fewou P, Geiger A. Bacteriome Diversity of Blackflies' Gut and Association with Onchocerca volvulus, the Causative Agent of Onchocerciasis in Mbam Valley (Center Region, Cameroon). Pathogens 2021; 11:pathogens11010044. [PMID: 35055992 PMCID: PMC8779297 DOI: 10.3390/pathogens11010044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/16/2021] [Accepted: 12/20/2021] [Indexed: 11/19/2022] Open
Abstract
Vector control using larvicides is the main alternative strategy to address limits of preventive chemotherapy using ivermectin for the control of onchocerciasis. However, it remains substantially limited by implementation difficulties, ecological concerns and the resistance of vector populations. Therefore, efficient and environmentally safe alternative control strategies are still needed. This study explores the composition of the blackfly bacteriome and its variability in the presence of Onchocerca volvulus infection, in order to determine their potential as a novel vector control-based approach to fight onchocerciasis. An entomological survey of a collection of samples was performed in the Bafia health district, a historical endemic focus for onchocerciasis in Cameroon. A total of 1270 blackflies were dissected and the infection rate was 10.1%, indicative of ongoing transmission of onchocerciasis in the surveyed communities. Sequencing process of blackflies’ gut DNA for bacteria screening revealed 14 phyla and 123 genera, highlighting the diversity of gut blackflies bacterial communities. Eight bacteria formed the core of blackfly bacteriome and Wolbachia was the predominant genus with 73.4% of relative abundance of blackflies’ gut bacterial communities. Acidomonas and Roseanomas genera were significantly abundant among infected blackflies (p = 0.01), whereas other genera such as Brevibacterium and Fructobacillus were associated with the absence of infection (p = 0.0009). Differences in gut bacterial distribution of blackflies according to their infection status by the parasite suggest a causal relationship between the bacteriome composition and the onset of blackflies’ infection by O. volvulus or vice versa. Blackfly native bacteria are then potentially involved in infection by O. volvulus, either by facilitating or preventing the parasite infestation of the vector. These bacteria represent an interesting potential as a biological tool/target for a novel approach of vector control to fight onchocerciasis.
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Affiliation(s)
- Arnauld Efon Ekangouo
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- Department of Biochemistry, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Hugues C. Nana Djeunga
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- Correspondence: ; Tel.: +237-699-076-499
| | - Guilhem Sempere
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- South Green Bioinformatics Platform, Biodiversity, F-34934 Montpellier, France
- UMR InterTryp, CIRAD (Centre de Coopération Internationale en Recherche Agronomique Pour le Développement), Campus International de Baillarguet, F-34398 Montpellier, France
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé I, Yaoundé, Cameroon
| | - Flobert Njiokou
- Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Paul Moundipa Fewou
- Department of Biochemistry, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
| | - Anne Geiger
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé P.O. Box 5797, Cameroon; (A.E.E.); (J.K.); (A.G.)
- UMR InterTryp, IRD (Institut de Recherche Pour le Développement), University of Montpellier, F-34394 Montpellier, France;
- Department of Animal Biology and Physiology, Faculty of Sciences, University of Yaoundé I, Yaoundé, Cameroon;
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Fernández-Santos NA, Prado-Velasco FG, Damián-González DC, Unnasch TR, Rodríguez-Pérez MA. Historical Review and Cost-Effectiveness Assessment of the Programs to Eliminate Onchocerciasis and Trachoma in Mexico. Res Rep Trop Med 2021; 12:235-245. [PMID: 34737667 PMCID: PMC8558426 DOI: 10.2147/rrtm.s317993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 09/07/2021] [Indexed: 11/29/2022] Open
Abstract
We present a historical review of two neglected tropical diseases (NTD), namely, onchocerciasis and trachoma, both which were successfully eliminated in Mexico. In addition, we present a cost-effectiveness assessment (CEA) demonstrating that these were worthwhile health interventions. Historically, an estimate of $310.68 and $38.92 per person were spent during the period of time the onchocerciasis and trachoma elimination programs operated, respectively.
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Affiliation(s)
- Nadia A Fernández-Santos
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Laboratorio de Biomedicina Molecular, Ciudad Reynosa, Tamaulipas, México
| | - Francisco Gibert Prado-Velasco
- Instituto de Salud del Estado de Chiapas, Programas de Tracoma y Oncocercosis en Chiapas, Tuxtla Gutiérrez, Chiapas, México
| | - Dey Carol Damián-González
- Instituto de Salud del Estado de Chiapas, Programas de Tracoma y Oncocercosis en Chiapas, Tuxtla Gutiérrez, Chiapas, México
| | - Thomas R Unnasch
- Global Health Infectious Disease Research Program, College of Public Health, University of South Florida, Tampa, FL, USA
| | - Mario A Rodríguez-Pérez
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Laboratorio de Biomedicina Molecular, Ciudad Reynosa, Tamaulipas, México
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6
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Mabey D, Agler E, Amuasi JH, Hernandez L, Hollingsworth TD, Hotez PJ, Lammie PJ, Malecela MN, Matendechero SH, Ottesen E, Phillips RO, Reeder JC, Szwarcwald CL, Shott JP, Solomon AW, Steer A, Swaminathan S. Towards a comprehensive research and development plan to support the control, elimination and eradication of neglected tropical diseases. Trans R Soc Trop Med Hyg 2021; 115:196-199. [PMID: 33179054 PMCID: PMC7842110 DOI: 10.1093/trstmh/traa114] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022] Open
Abstract
To maximise the likelihood of success, global health programmes need repeated, honest appraisal of their own weaknesses, with research undertaken to address any identified gaps. There is still much to be learned to optimise work against neglected tropical diseases. To facilitate that learning, a comprehensive research and development plan is required. Here, we discuss how such a plan might be developed.
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Affiliation(s)
- David Mabey
- Clinical Research Department, London School of Hygiene & Tropical Medicine, London WC1E 7HT, UK
| | | | - John H Amuasi
- African Research Network for Neglected Tropical Diseases, Kumasi AK-039-5028, Ghana
| | - Leda Hernandez
- Department of Health, Infectious Disease Office, National Center for Disease Prevention and Control, Manila 1003, Philippines
| | - T Déirdre Hollingsworth
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford OX3 7LF, UK
| | - Peter J Hotez
- Departments of Pediatrics and Molecular Virology & Microbiology, Texas Children's Hospital Center for Vaccine Development, National School of Tropical Medicine, Baylor College of Medicine, Houston, TX 77030s, USA.,Hagler Institute for Advanced Study at Texas A & M University, College Station, TX 77843, USA.,Department of Biology, Baylor University, Waco, TX 76706, USA.,James A. Baker III Institute of Public Policy, Rice University, Houston, TX 77005, USA.,Scowcroft Institute of International Affairs, Bush School of Government and Public Service, Texas A & M University, College Station, TX 77845, USA
| | - Patrick J Lammie
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, GA 30030, USA
| | - Mwelecele N Malecela
- Department of Control of Neglected Tropical Diseases, WHO 1211, Geneva, Switzerland
| | - Sultani H Matendechero
- Division of Communicable Disease Prevention and Control, Neglected Tropical Diseases Unit, Ministry of Health, Nairobi, Kenya
| | - Eric Ottesen
- Neglected Tropical Diseases Support Center, Task Force for Global Health, Decatur, GA 30030, USA
| | - Richard O Phillips
- Kumasi Center for Collaborative Research in Tropical Medicine, Kwame Nkrumah University of Science and Technology, Kumasi AK-039-5028, Ghana
| | - John C Reeder
- UNICEF, UNDP, World Bank, WHO Special Programme for Research and Training in Tropical Disease (TDR), 1211 Geneva 21040-900, Switzerland
| | - Célia Landmann Szwarcwald
- Instituto de Comunicação e Informação Científica e Tecnológica em Saúde, Fundação Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brasil
| | - Joseph P Shott
- Division of Neglected Tropical Diseases, Office of Infectious Diseases, Bureau for Global Health, USAID, Washington, DC 20004, USA
| | - Anthony W Solomon
- Department of Control of Neglected Tropical Diseases, WHO 1211, Geneva, Switzerland
| | - Andrew Steer
- Department of Paediatrics, University of Melbourne, Melbourne, Victoria 3010, Australia.,Department of General Medicine, Royal Children's Hospital, Melbourne, Victoria 3052, Australia.,Tropical Diseases Research Group, Murdoch Children's Research Institute, Melbourne, Victoria 3052, Australia
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7
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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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Izwan-Anas N, Ya'cob Z, Low VL, Lourdes EY, Ramli R, Bolongan G, Takaoka H. Simulium (Gomphostilbia) aziruni: First record of a black fly (Diptera: Simuliidae) attracted to a human in Malaysia. Acta Trop 2021; 218:105904. [PMID: 33775626 DOI: 10.1016/j.actatropica.2021.105904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 11/18/2022]
Abstract
Most female black flies in the genus Simulium are blood-sucking flies and they can cause various parasitic diseases in human and animal. A total of 94 species of black flies have been reported in Malaysia, however, their biting behavior and role as vector of infectious agents remain understudied. To fill in this knowledge gap, we attempted to survey adult black flies from field populations in Peninsular Malaysia. In a survey carried out in 2017 at Tasik Kenyir, Terengganu, three females were caught while attracted and landed on human skin. Further morphological and molecular analyses showed that the specimens were identical to Simulium (Gomphostilbia) aziruni Takaoka, Hashim & Chen of the Simulium gombakense species-group. This is the first report on a black fly species attracted to human in Malaysia which serves as a steppingstone towards in-depth studies for black flies in this region.
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Affiliation(s)
- Noor Izwan-Anas
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Zubaidah Ya'cob
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia.
| | - Van Lun Low
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia.
| | - Emmanuel Y Lourdes
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Rosli Ramli
- Institute of Biological Sciences, Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Gilmoore Bolongan
- Department of Wildlife and Nature Parks Peninsular Malaysia (PERHILITAN), KM 10, Jalan Cheras, Kuala Lumpur 56100, Malaysia
| | - Hiroyuki Takaoka
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
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9
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Bennuru S, Oduro-Boateng G, Osigwe C, Del Valle P, Golden A, Ogawa GM, Cama V, Lustigman S, Nutman TB. Integrating Multiple Biomarkers to Increase Sensitivity for the Detection of Onchocerca volvulus Infection. J Infect Dis 2021; 221:1805-1815. [PMID: 31201416 DOI: 10.1093/infdis/jiz307] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/13/2019] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Serological assessments for human onchocerciasis are based on IgG4 reactivity against the OV-16 antigen, with sensitivities of 60-80%. We have previously identified 7 novel proteins that could improve serodiagnosis. METHODS IgG4 responses to these 7 proteins were assessed by luciferase immunoprecipitation (LIPS) and enzyme-linked immunosorbent (ELISA) immunoassays. RESULTS OVOC10469 and OVOC3261 were identified as the most promising candidates by IgG4-based immunoassays with sensitivities of 53% for rOVOC10469 and 78% for rOVOC3261 while specificity for each was >99%. These 2 antigens in combination with OV-16 increased the sensitivity for patent infections to 94%. The kinetics of appearance of these IgG4 responses based on experimentally infected non-human primates indicated that they were microfilarial- driven. Further, the IgG4 responses to both OVOC10469 and OVOC3261 (as well as to OV-16) drop significantly (p<0.05) following successful treatment for onchocerciasis. A prototype lateral flow rapid diagnostic test to detect IgG4 to both Ov-16 and OVOC3261 was developed and tested demonstrating an overall 94% sensitivity. CONCLUSION The combined use of rOVOC3261 with OV-16 improved serologic assessment of O. volvulus infection, a current unmet need toward the goal of elimination of transmission of O. volvulus.
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Affiliation(s)
- Sasisekhar Bennuru
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Georgiette Oduro-Boateng
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Chinweoke Osigwe
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | - Priscilla Del Valle
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
| | | | - Guilherme Maerschner Ogawa
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Vitaliano Cama
- Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Sara Lustigman
- Laboratory of Molecular Parasitology, Lindsley F. Kimball Research Institute, New York Blood Center
| | - Thomas B Nutman
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
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10
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Estrada-Franco JG, Fernández-Santos NA, Adebiyi AA, López-López MDJ, Aguilar-Durán JA, Hernández-Triana LM, Prosser SWJ, Hebert PDN, Fooks AR, Hamer GL, Xue L, Rodríguez-Pérez MA. Vertebrate-Aedes aegypti and Culex quinquefasciatus (Diptera)-arbovirus transmission networks: Non-human feeding revealed by meta-barcoding and next-generation sequencing. PLoS Negl Trop Dis 2020; 14:e0008867. [PMID: 33382725 PMCID: PMC7806141 DOI: 10.1371/journal.pntd.0008867] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 01/13/2021] [Accepted: 10/09/2020] [Indexed: 01/06/2023] Open
Abstract
Background Aedes aegypti mosquito-borne viruses including Zika (ZIKV), dengue (DENV), yellow fever (YFV), and chikungunya (CHIKV) have emerged and re-emerged globally, resulting in an elevated burden of human disease. Aedes aegypti is found worldwide in tropical, sub-tropical, and temperate areas. The characterization of mosquito blood meals is essential to understand the transmission dynamics of mosquito-vectored pathogens. Methodology/principal findings Here, we report Ae. aegypti and Culex quinquefasciatus host feeding patterns and arbovirus transmission in Northern Mexico using a metabarcoding-like approach with next-generation deep sequencing technology. A total of 145 Ae. aegypti yielded a blood meal analysis result with 107 (73.8%) for a single vertebrate species and 38 (26.2%) for two or more. Among the single host blood meals for Ae. aegypti, 28.0% were from humans, 54.2% from dogs, 16.8% from cats, and 1.0% from tortoises. Among those with more than one species present, 65.9% were from humans and dogs. For Cx. quinquefasciatus, 388 individuals yielded information with 326 (84%) being from a single host and 63 (16.2%) being from two or more hosts. Of the single species blood meals, 77.9% were from dogs, 6.1% from chickens, 3.1% from house sparrows, 2.4% from humans, while the remaining 10.5% derived from other 12 host species. Among those which had fed on more than one species, 11% were from dogs and humans, and 89% of other host species combinations. Forage ratio analysis revealed dog as the most over-utilized host by Ae. aegypti (= 4.3) and Cx. quinquefasciatus (= 5.6) and the human blood index at 39% and 4%, respectively. A total of 2,941 host-seeking female Ae. aegypti and 3,536 Cx. quinquefasciatus mosquitoes were collected in the surveyed area. Of these, 118 Ae. aegypti pools and 37 Cx. quinquefasciatus pools were screened for seven arboviruses (ZIKV, DENV 1–4, CHIKV, and West Nile virus (WNV)) using qRT-PCR and none were positive (point prevalence = 0%). The 95%-exact upper limit confidence interval was 0.07% and 0.17% for Ae. aegypti and Cx. quinquefasciatus, respectively Conclusions/significance The low human blood feeding rate in Ae. aegypti, high rate of feeding on mammals by Cx. quinquefasciatus, and the potential risk to transmission dynamics of arboviruses in highly urbanized areas of Northern Mexico is discussed. Elucidating arbovirus-vector-host contact networks is critical to understand and control mosquito-borne virus transmission, including pathogens such as ZIKV, DENV 1–4, CHIKV, and WNV. Here, we report the results of metabarcoding of blood meals of two primary pathogen mosquito vectors, Aedes aegypti and Culex quinquefasciatus. We found limited human blood feeding by Ae. aegypti and high preference for feeding on mammals by Cx. quinquefasciatus. Interestingly, blood meal analysis revealed dogs as the most utilized host for both vector species suggesting the potential for zooprophylaxis for human-amplified urban arboviruses. Pools of these vector species were tested for seven arboviruses and all were negative. We calculated vectorial capacity to discuss the potential risk and transmission dynamics of pathogens transmitted by these two important vectors in an urban location in Northern Mexico.
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Affiliation(s)
| | - Nadia A. Fernández-Santos
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Ciudad Reynosa, Tamaulipas, México
| | - Adeniran A. Adebiyi
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Ciudad Reynosa, Tamaulipas, México
| | - María de J. López-López
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Ciudad Reynosa, Tamaulipas, México
| | - Jesús A. Aguilar-Durán
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Ciudad Reynosa, Tamaulipas, México
| | | | | | - Paul D. N. Hebert
- Centre for Biodiversity Genomics, University of Guelph, Ontario, Canada
| | - Anthony R. Fooks
- Animal and Plant Health Agency, Woodham Lane, Addlestone, Surrey, United Kingdom
| | - Gabriel L. Hamer
- Department of Entomology, Texas A&M University, College Station, Texas, United States of America
| | - Ling Xue
- College of Mathematical Sciences, Harbin Engineering University, Harbin, Heilongjiang, P.R. China
| | - Mario A. Rodríguez-Pérez
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Ciudad Reynosa, Tamaulipas, México
- * E-mail: ,
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11
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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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12
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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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13
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Designing antifilarial drug trials using clinical trial simulators. Nat Commun 2020; 11:2685. [PMID: 32483209 PMCID: PMC7264235 DOI: 10.1038/s41467-020-16442-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 05/03/2020] [Indexed: 12/01/2022] Open
Abstract
Lymphatic filariasis and onchocerciasis are neglected tropical diseases (NTDs) targeted for elimination by mass (antifilarial) drug administration. These drugs are predominantly active against the microfilarial progeny of adult worms. New drugs or combinations are needed to improve patient therapy and to enhance the effectiveness of interventions in persistent hotspots of transmission. Several therapies and regimens are currently in (pre-)clinical testing. Clinical trial simulators (CTSs) project patient outcomes to inform the design of clinical trials but have not been widely applied to NTDs, where their resource-saving payoffs could be highly beneficial. We demonstrate the utility of CTSs using our individual-based onchocerciasis transmission model (EPIONCHO-IBM) that projects trial outcomes of a hypothetical macrofilaricidal drug. We identify key design decisions that influence the power of clinical trials, including participant eligibility criteria and post-treatment follow-up times for measuring infection indicators. We discuss how CTSs help to inform target product profiles. Drugs for filariases are under development and clinical trial simulators could help to inform the design of clinical trials. Here, Walker et al. use an individual-based onchocerciasis transmission model to project trial outcomes of a hypothetical macrofilaricidal drug, resolving key design choices.
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14
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Oforka LC, Adeleke MA, Anikwe JC, Hardy NB, Mathias DK, Makanjuola WA, Fadamiro HY. Biting Rates and Onchocerca Infectivity Status of Black Flies from the Simulium damnosum Complex (Diptera: Simuliidae) in Osun State, Nigeria. JOURNAL OF MEDICAL ENTOMOLOGY 2020; 57:901-907. [PMID: 31901168 DOI: 10.1093/jme/tjz250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Indexed: 06/10/2023]
Abstract
The Simulium damnosum Theobald complex transmits Onchocerca volvulus Leuckart (Spirurida: Onchocercidae), the causative agent of onchocerciasis. Recent evidence suggests that control efforts have strongly suppressed parasite populations, but vector surveillance is needed in parts of Africa where the disease remains endemic. Here, studies on biting rates and infectivity status of suspected vector species were conducted in three onchocerciasis-endemic areas, namely Iwo, Ede, and Obokun, in Osun State, Nigeria. A total of 3,035 black flies were collected between October 2014 and September 2016, and examined for parity and parasites using standard methods. A separate collection of 2,000 black flies was pool-screened for infectivity using polymerase chain reaction (PCR) amplification of the O-150 marker. Results showed that parous flies were significantly less common than nulliparous flies with overall parous rates of 8.02% in Iwo and 35.38% in Ede at the end of the study period. Obokun had a parous rate of 22.22% obtained in the first year only. None of the dissected parous flies were infected with O. volvulus and PCR assays showed no amplification of O-150 O. volvulus-specific repeats in head and body pools. However, annual biting rates exceeded the World Health Organization threshold of 1,000 bites/person/yr. Thus it appears that, with such high rates of biting, even low levels of vector infection can sustain onchocerciasis in African communities.
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Affiliation(s)
- Linda C Oforka
- Department of Zoology, University of Lagos, Akoka, Yaba, 101017, Lagos, Nigeria
| | - Monsuru A Adeleke
- Department of Zoology, Osun State University, P.M.B 4494, Osogbo, Nigeria
| | - Joseph C Anikwe
- Department of Zoology, University of Lagos, Akoka, Yaba, 101017, Lagos, Nigeria
| | - Nate B Hardy
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL
| | - Derrick K Mathias
- Florida Medical Entomology Laboratory, Institute of Food and Agricultural Sciences, University of Florida, Vero Beach, FL
| | | | - Henry Y Fadamiro
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL
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15
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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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16
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Fernández-Santos NA, Unnasch TR, Rodríguez-Luna IC, Prado-Velasco FG, Adeniran AA, Martínez-Montoya H, Rodríguez-Pérez MA. Post-elimination surveillance in formerly onchocerciasis endemic focus in Southern Mexico. PLoS Negl Trop Dis 2020; 14:e0008008. [PMID: 31999704 PMCID: PMC7012445 DOI: 10.1371/journal.pntd.0008008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 02/11/2020] [Accepted: 12/19/2019] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND All formerly endemic communities of the Southern Chiapas focus of onchocerciasis in Mexico were treated with ivermectin until parasite transmission was eliminated by 2015. Transmission of onchocerciasis did not resume during a period of three years (2012-2014) following the final distribution of ivermectin in 2011; it was thus concluded that transmission remained undetectable without intervention. WHO thus declared the elimination of transmission of onchocerciasis from Mexico in 2015. METHODOLOGY/PRINCIPAL FINDINGS From 2016 to the present, post-elimination surveillance (PES) based on examination for suspected onchocercomas was performed in the former Southern Chiapas focus. Each year, over 60% of the total population (range = 85,347-104,106 individuals) of the formerly endemic communities were examined for onchocercomas. Thirty-four individuals were found harboring suspected onchocercomas in the PES surveys conducted from 2016-2019. Of these, one female of 7 years of age who had immigrated from a formerly endemic focus, harbored an infertile (sterile) female in the suspected onchocercoma; all others were negative. Skin biopsy assessments were performed from March through May 2017 in three communities where the female resided. None of the 83 individuals of the three communities examined by skin biopsy were mf positive. Similarly, none of the biopsies from the individuals were found to contain parasite DNA when tested by polymerase chain reaction-enzyme-linked immunosorbent assay (PCR-ELISA). CONCLUSIONS/SIGNIFICANCE These provide support to the conclusion that onchocerciasis has been eliminated from Mexico.
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Affiliation(s)
| | - Thomas R. Unnasch
- Center for Global Health Infectious Diseases Research, University of South Florida, Tampa, Florida, United States of America
| | | | | | - Adebiyi A. Adeniran
- Instituto Politécnico Nacional, Centro de Biotecnología Genómica, Reynosa, Tamaulipas, México
| | - Humberto Martínez-Montoya
- Unidad Académica Multidisciplinaria Reynosa Aztlan—Universidad Autónoma de Tamaulipas, Reynosa, Tamaulipas, México
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17
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Cupp E, Sauerbrey M, Cama V, Eberhard M, Lammie PJ, Unnasch TR. Elimination of onchocerciasis in Africa by 2025: the need for a broad perspective. Infect Dis Poverty 2019; 8:50. [PMID: 31303176 PMCID: PMC6628485 DOI: 10.1186/s40249-019-0557-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 05/28/2019] [Indexed: 12/16/2022] Open
Abstract
Background In response to the recent publication “Is onchocerciasis elimination in Africa feasible by 2025: a perspective based on lessons learnt from the African control programmes” by Dadzie et al., it is important to clarify and highlight the positive and unequivocal research and operational contributions from the American experience towards the worldwide elimination of human onchocerciasis (river blindness). Main text The strategies of twice or more rounds of mass drug administration (MDA) of ivermectin per year, as well as the use of OV-16 serology have allowed four American countries to be verified by World Health Organization to have eliminated transmission of Onchocerca volvulus, the etiological agent. These advances were also implemented in Sudan and Uganda; currently, both are the only African countries where ivermectin MDA was safely stopped in several transmission zones. Conclusions Programmatic treatment and evaluation approaches, pioneered in the Americas, are the most efficient among the existing tools for elimination, and their broader use could catalyze the successful elimination of this disease in Africa. Electronic supplementary material The online version of this article (10.1186/s40249-019-0557-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ed Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL, 36849, USA
| | - Mauricio Sauerbrey
- Onchocerciasis Elimination Program for the Americas, 14 Calle 3-51 Zona 10, Edificio Murano Center, Oficina, 1401, Guatemala City, Guatemala
| | - Vitaliano Cama
- Centers for Disease Control and Prevention, 1600 Clifton Rd, MS D-65, Atlanta, GA, 30329, USA
| | - Mark Eberhard
- Centers for Disease Control and Prevention, 1600 Clifton Rd, MS D-65, Atlanta, GA, 30329, USA
| | - Patrick J Lammie
- Task Force for Global Health, 330 W. Ponce de Leon Ave, Decatur, GA, 30030, USA
| | - Thomas R Unnasch
- Center for Global Health Infectious Diseases, University of South Florida College of Public Health, 3720 Spectrum Blvd, Suite 304, Tampa, FL, 33612, USA.
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Cantey PT, Roy SL, Boakye D, Mwingira U, Ottesen EA, Hopkins AD, Sodahlon YK. Transitioning from river blindness control to elimination: steps toward stopping treatment. Int Health 2019; 10:i7-i13. [PMID: 29471338 PMCID: PMC5881257 DOI: 10.1093/inthealth/ihx049] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 10/31/2017] [Indexed: 11/18/2022] Open
Abstract
The transition from onchocerciasis control to elimination requires country programmes to rethink their approach to a variety of activities as they move from addressing morbidity to addressing transmission of the parasite. Although the 2016 WHO guidelines provide extensive recommendations, it was beyond the scope of the document to provide guidance on all aspects of the transition. This paper will discuss some of the important issues that programmes are grappling with as they transition to elimination and provide some potential approaches that programmes can use to address them. Although there are some data to support some aspects of the suggested approaches, operational research will be needed to generate data to support these approaches further and to determine how programmes could best tailor them to their own unique epidemiological challenges. Good communication between the national programmes and the broader global programme will facilitate the clear articulation of programmatic challenges and the development of the evidence to support programme decision-making.
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Affiliation(s)
- Paul T Cantey
- Department of Neglected Tropical Diseases, World Health Organization, Geneva 1211, Switzerland
| | - Sharon L Roy
- Division of Parasitic Diseases and Malaria, U.S. Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
| | - Daniel Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, LG581, Ghana
| | - Upendo Mwingira
- Neglected Tropical Diseases Control Programme, Ministry of Health, Community Development, Gender, Elderly and Children, Dar es Salaam 11478, Tanzania.,National Institute for Medical Research, Dar es Salaam 11101, Tanzania
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19
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Sauerbrey M, Rakers LJ, Richards FO. Progress toward elimination of onchocerciasis in the Americas. Int Health 2019; 10:i71-i78. [PMID: 29471334 DOI: 10.1093/inthealth/ihx039] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 11/30/2017] [Indexed: 11/14/2022] Open
Abstract
The Onchocerciasis Elimination Program for the Americas (OEPA) is a regional initiative and international partnership that has made considerable progress toward its goal since it was launched in 1993. Its strategy is based on mass drug administration of ivermectin (Mectizan, donated by MSD, also known as Merck & Co., Inc., Kenilworth, NJ, USA), twice or four times per year, with at least 85% coverage of eligible populations. From 1989 to 2016, 11 741 276 ivermectin treatments have been given in the Americas, eliminating transmission in 11 of 13 foci. The OEPA's success has had a great influence on programs in Africa, especially Sudan and Uganda, which moved from a control to an elimination strategy in 2006 and 2007, respectively. The successes in the Americas have also greatly influenced WHO guidelines for onchocerciasis transmission elimination. With four of the six originally endemic American countries now WHO verified as having eliminated onchocerciasis transmission, and 95% of ivermectin treatments in the region halted, the regional focus is now on the remaining active transmission zone, called the Yanomami Area, on the border between Venezuela and Brazil. Both countries have difficult political climates that hinder the elimination task in this remote and relatively neglected region. As with other elimination efforts, 'the final inch' is often the most difficult task of all.
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Affiliation(s)
- Mauricio Sauerbrey
- Onchocerciasis Elimination Program for the Americas, Guatemala City, Guatemala
| | - Lindsay J Rakers
- Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA 30307, USA
| | - Frank O Richards
- Carter Center, One Copenhill, 453 Freedom Parkway, Atlanta, GA 30307, USA
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20
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Oforka LC, Adeleke MA, Anikwe JC, Makanjuola WA. Population Fluctuations and Effect of Climatic Factors on the Relative Abundance of Simulium damnosum Complex (Diptera: Simuliidae). ENVIRONMENTAL ENTOMOLOGY 2019; 48:284-290. [PMID: 30715252 DOI: 10.1093/ee/nvz004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Indexed: 06/09/2023]
Abstract
Simulium damnosum (Theobald) sensu lato (s.l.) is a complex of many species of black flies that transmit Onchocerca volvulus (Leuckart) to varying capacities based on their ecological zones in Africa. The presence of three ecological zones in Osun, an onchocerciasis endemic state in Nigeria, is the basis of this study that is aimed at determining the population dynamics of S. damnosum s.l. in the state. Adult S. damnosum s.l. were collected fortnightly in the wet and dry seasons for 2 yr between October 2014 and September 2016 in the Guinea savanna (Iwo), derived savannah (Ede), and rainforest (Obokun) zones. Temperature, relative humidity, and rainfall of the study area were measured. The results showed that in the first year, Ede had 62.8% of the total black fly population while Obokun had the lowest (1.5%). In the second year, Iwo had 94.1% of the total black fly population while Obokun had the least population. The black fly population was significantly higher during the wet season than dry season in Iwo and Ede, but was not significant in Obokun. The results further showed that black fly populations were strongly correlated with ambient temperature and rainfall in Iwo, whereas no relationships were recorded for Ede and Obokun. The results suggest that abundance of black flies during the wet season was due to increased rainfall which in turn created rapids and conditions suitable for development of preimaginal stages into adults. These vector surveillance findings will guide control decisions necessary for endemic communities to meet elimination targets.
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Affiliation(s)
- Linda C Oforka
- Department of Zoology, University of Lagos, Lagos, Nigeria
| | - Monsuru A Adeleke
- Department of Biological Sciences, Osun State University, Osogbo, Nigeria
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Walker M, Stolk WA, Dixon MA, Bottomley C, Diawara L, Traoré MO, de Vlas SJ, Basáñez MG. Modelling the elimination of river blindness using long-term epidemiological and programmatic data from Mali and Senegal. Epidemics 2018; 18:4-15. [PMID: 28279455 PMCID: PMC5340858 DOI: 10.1016/j.epidem.2017.02.005] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 02/03/2017] [Accepted: 02/07/2017] [Indexed: 11/11/2022] Open
Abstract
Onchocerciasis is earmarked for elimination in some African countries by 2020/2025. 15+ years of ivermectin treatment drove infection prevalence to zero in areas of Mali & Senegal. Data-driven model projections are used to evaluate the risk of infection resurgence. Latent infections can initiate slow resurgence in communities with high transmission propensity. Highly sensitive and long-term surveillance will be necessary to verify elimination.
The onchocerciasis transmission models EPIONCHO and ONCHOSIM have been independently developed and used to explore the feasibility of eliminating onchocerciasis from Africa with mass (annual or biannual) distribution of ivermectin within the timeframes proposed by the World Health Organization (WHO) and endorsed by the 2012 London Declaration on Neglected Tropical Diseases (i.e. by 2020/2025). Based on the findings of our previous model comparison, we implemented technical refinements and tested the projections of EPIONCHO and ONCHOSIM against long-term epidemiological data from two West African transmission foci in Mali and Senegal where the observed prevalence of infection was brought to zero circa 2007–2009 after 15–17 years of mass ivermectin treatment. We simulated these interventions using programmatic information on the frequency and coverage of mass treatments and trained the model projections using longitudinal parasitological data from 27 communities, evaluating the projected outcome of elimination (local parasite extinction) or resurgence. We found that EPIONCHO and ONCHOSIM captured adequately the epidemiological trends during mass treatment but that resurgence, while never predicted by ONCHOSIM, was predicted by EPIONCHO in some communities with the highest (inferred) vector biting rates and associated pre-intervention endemicities. Resurgence can be extremely protracted such that low (microfilarial) prevalence between 1% and 5% can be maintained for 3–5 years before manifesting more prominently. We highlight that post-treatment and post-elimination surveillance protocols must be implemented for long enough and with high enough sensitivity to detect possible residual latent infections potentially indicative of resurgence. We also discuss uncertainty and differences between EPIONCHO and ONCHOSIM projections, the potential importance of vector control in high-transmission settings as a complementary intervention strategy, and the short remaining timeline for African countries to be ready to stop treatment safely and begin surveillance in order to meet the impending 2020/2025 elimination targets.
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Affiliation(s)
- Martin Walker
- Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, Norfolk Place, W2 1 PG, London, UK; Department of Pathobiology and Population Sciences and London Centre for Neglected Tropical Disease Research, Royal Veterinary College, Hawkshead Lane, Hatfield, AL9 7TA, UK.
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - Matthew A Dixon
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands; MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK; Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, Norfolk Place, W2 1 PG, London, UK
| | - Christian Bottomley
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands; MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK
| | - Lamine Diawara
- Inter-Country Support Team for West Africa, World Health Organization 158, Place de l'Indépendance 03 BP 7019, Ouagadougou 03, Burkina Faso
| | - Mamadou O Traoré
- Programme National de Lutte contre l'Onchocercose (PNLO), Direction Nationale de la Santé (DNS), B.P. 233, Bamako, Mali
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands
| | - María-Gloria Basáñez
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands; MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, UK; Department of Infectious Disease Epidemiology and London Centre for Neglected Tropical Disease Research, Imperial College London, Norfolk Place, W2 1 PG, London, UK
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Nicholls RS, Duque S, Olaya LA, López MC, Sánchez SB, Morales AL, Palma GI. Elimination of onchocerciasis from Colombia: first proof of concept of river blindness elimination in the world. Parasit Vectors 2018; 11:237. [PMID: 29642939 PMCID: PMC5896109 DOI: 10.1186/s13071-018-2821-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 03/26/2018] [Indexed: 11/22/2022] Open
Abstract
Background Onchocerciasis is a chronic parasitic infection originally endemic in 13 discrete regional foci distributed among six countries of Latin America (Brazil, Colombia, Ecuador, Guatemala, Mexico and Venezuela). In Colombia, this disease was discovered in 1965 in the Pacific Coast of the country. The National Onchocerciasis Elimination Program was established in 1993 with the aim of eliminating disease morbidity and infection transmission. In 2013, the World Health Organization (WHO) verified Colombia as free of onchocerciasis, becoming the first country in the world to reach such a goal. This report provides the empirical evidence of the elimination of Onchocerca volvulus transmission by Simulium exiguum (s.l.) after 12 years of 6-monthly mass drug administration of Mectizan® (ivermectin) to all the eligible residents living in this endemic area. Methods From 1996 onwards, a biannual community-based mass ivermectin administration programme was implemented, complemented by health education and community participation. In-depth parasitological, serological and entomological surveys were conducted periodically between 1998 and 2007 to evaluate the impact of ivermectin treatment according to the 2001 WHO guidelines. When the interruption of parasite transmission was demonstrated, the drug distribution ceased and a three-year post-treatment surveillance (PTS) period (2008–2010) was initiated. Results After 23 rounds of treatment, parasitological and ophthalmological assessments showed absence of microfilariae in skin and anterior chamber of the eyes. Serological tests proved lack of antibodies against O. volvulus in children under 10 years-old. A total of 10,500 S. exiguum flies tested by PCR had no L3 infection (infectivity rate = 0.0095%; 95% CI: 0.0029–0.049) during 2004, indicating interruption of parasite transmission. However, biannual ivermectin treatments continued until 2007 followed by a 3-year PTS period at the end of which 13,481 flies were analyzed and no infective flies were found (infectivity rate = 0%; 95% CI: 0.0–0.014). Conclusions These results fulfilled the WHO criteria for onchocerciasis elimination. Consequently, in 2013 Colombia was verified as free of onchocerciasis, demonstrating that elimination of this neglected tropical disease is an achievable goal and paving the way for an elimination agenda to be followed by other endemic countries in Latin America and Africa.
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Affiliation(s)
- Rubén Santiago Nicholls
- Grupo de Parasitología, Instituto Nacional de Salud, Avenida Calle 26 No. 51-20, Bogotá, DC CP 111321, Colombia.
| | - Sofía Duque
- Grupo de Parasitología, Instituto Nacional de Salud, Avenida Calle 26 No. 51-20, Bogotá, DC CP 111321, Colombia
| | - Luz Adriana Olaya
- Laboratorio Departamental de Salud Pública, Secretaría Departamental de Salud del Cauca, Calle 5 No. 15-57, Popayán, Cauca, CP 190003, Colombia
| | - Myriam Consuelo López
- Departamento de Salud Pública, Facultad de Medicina, Universidad Nacional de Colombia, Ciudad Universitaria, Bogotá, DC CP 111321, Colombia
| | - Sol Beatriz Sánchez
- Consultant Health Education, Colombian Onchocerciasis Elimination Program, Carrera 93 # 16-90, Cali, CP 760032, Colombia
| | - Alba Lucía Morales
- Onchocerciasis Elimination Program for the Americas (OEPA), 14 calle 3-51, zona 10, Edificio Murano Center, CP 01010, Guatemala, Guatemala
| | - Gloria Inés Palma
- Departamento de Microbiologia, Facultad de Salud, Universidad del Valle, Campus San Fernando, Calle 4B No. 36-00, CP 760043, Cali, Colombia
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Komlan K, Vossberg PS, Gantin RG, Solim T, Korbmacher F, Banla M, Padjoudoum K, Karabou P, Köhler C, Soboslay PT. Onchocerca volvulus infection and serological prevalence, ocular onchocerciasis and parasite transmission in northern and central Togo after decades of Simulium damnosum s.l. vector control and mass drug administration of ivermectin. PLoS Negl Trop Dis 2018; 12:e0006312. [PMID: 29494606 PMCID: PMC5849363 DOI: 10.1371/journal.pntd.0006312] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 03/13/2018] [Accepted: 02/12/2018] [Indexed: 11/18/2022] Open
Abstract
Background Mass drug administration (MDA) of ivermectin has become the main intervention to control onchocerciasis or “river blindness”. In Togo, after many years of MDA, Onchocerca volvulus infection has declined dramatically, and elimination appears achievable, but in certain river basins the current situation remains unknown. We have conducted parasitological, serological, ophthalmological, and entomological assessments in northern and central Togo within the river basins of Ôti, Kéran and Mô. Methodology/Principal findings Examinations were completed in 1,455 participants from 11 onchocerciasis sentinel villages, and O. volvulus transmission by Simulium damnosum sensu lato (s.l.) was evaluated. In children (aged 1–10 years), the prevalence of microfilariae (Mf) was 2.3% and in adults it ranged from 5.1 to 13.3%. Positive IgG4 responses to O. volvulus adult (crude) worm antigen (OvAg) and the recombinant Ov16 antigen were in all-ages 48.7% and 34.4%, and 29.1% and 14.9% in children, respectively. In the river basin villages of Kéran, Mô and Ôti, the IgG4 seroprevalences to OvAg in children were 51.7%, 23.5% and 12.7%, respectively, and to the Ov16 antigen 33.3% (Kéran) and 5.2% (Ôti). Onchocerciasis ocular lesions (punctate keratitis, evolving iridocyclitis and chorioretinitis) were observed in children and young adults. O. volvulus-specific DNA (Ov150) was detected by poolscreen in vector samples collected from Tchitchira/Kéran(22.8%), Bouzalo/Mô(11.3%), Baghan/Mô(2.9%) and Pancerys/Ôti(4.9%); prevalences of O. volvulus infection in S. damnosum s.l. were, respectively, 1%, 0.5%, 0.1% and 0.2%. Conclusions/Significance In the northern and central river basins in Togo, interruption of O. volvulus transmission has not yet been attained. Patent O. volvulus infections, positive antibody responses, progressive ocular onchocerciasis were diagnosed, and parasite transmission by S. damnosum s.l. occurred close to the survey locations. Future interventions may require approaches selectively targeted to non-complying endemic populations, to the seasonality of parasite transmission and national onchocerciasis control programs should harmonize cross-border MDA as a coordinated intervention. Mass drug administration (MDA) with ivermectin has become the main tool in the efforts to control and eliminate onchocerciasis (“river blindness”). In some areas, and after many years of MDA, levels of Onchocerca volvulus infection (the causative parasite) have declined greatly, and elimination appears achievable. In certain river basins of northern and central Togo, the present epidemiological situation remains unknown. The guidelines of the World Health Organization recommend that before ivermectin MDA can be stopped, interruption of O. volvulus transmission must be demonstrated. To this end, parasitological, serological, ophthalmological, and entomological assessments were conducted in the Ôti, Kéran and Mô river basins. O. volvulus infections and positive antibody responses were found in children aged ≤10 years and adults. Progressive ocular onchocerciasis was diagnosed, and parasite transmission by Simulium damnosum s.l. (the disease vector) occurred close to the survey locations. Thus, O. volvulus transmission continues in northern and central Togo, and future interventions may require approaches selectively adapted to seasonal migration of non-complying endemic populations in and out of the river basins, as well as seasonal transmission by the vectors. National control programmes should harmonize cross-border MDA as a coordinated intervention.
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Affiliation(s)
- Kossi Komlan
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | - Patrick S. Vossberg
- Institute for Tropical Medicine, University of Tübingen, University Clinics, Tübingen, Germany
| | - Richard G. Gantin
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
- Institute for Tropical Medicine, University of Tübingen, University Clinics, Tübingen, Germany
| | - Tchalim Solim
- Centre Hospitalier Universitaire Campus, Université de Lomé, Lomé, Togo
| | - Francois Korbmacher
- Institute for Tropical Medicine, University of Tübingen, University Clinics, Tübingen, Germany
| | - Méba Banla
- Centre Hospitalier Universitaire Campus, Université de Lomé, Lomé, Togo
| | | | | | - Carsten Köhler
- Institute for Tropical Medicine, University of Tübingen, University Clinics, Tübingen, Germany
| | - Peter T. Soboslay
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
- Institute for Tropical Medicine, University of Tübingen, University Clinics, Tübingen, Germany
- * E-mail:
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Unnasch TR, Golden A, Cama V, Cantey PT. Diagnostics for onchocerciasis in the era of elimination. Int Health 2018; 10:i20-i26. [PMID: 29471336 PMCID: PMC5881263 DOI: 10.1093/inthealth/ihx047] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Revised: 10/19/2017] [Accepted: 11/06/2017] [Indexed: 12/31/2022] Open
Abstract
In the past few years, efforts to eliminate onchocerciasis from Africa have intensified. These efforts are primarily based on the mass distribution of the anti-helminthic drug Mectizan™ (ivermectin). This program has led to the development of new guidelines by the World Health Organization for the verification that transmission has been suppressed and eventually eliminated. The requirements of diagnostic tools for this purpose differ in many ways from tests used to diagnose infection in individuals. In this review, we summarize the progress that has been made to identify diagnostics that meet the specialized requirements needed to verify onchocerciasis elimination, discuss why these tests were selected and summarize the needs that still exist to complete the arsenal of diagnostic tools that will be useful as the goal of elimination is achieved.
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Affiliation(s)
- Thomas R Unnasch
- Center for Global Health Infectious Disease Research, College of Public Health, University of South Florida, 3720 Spectrum Blvd., Suite 304, Tampa, FL 33612, USA
| | | | - Vitaliano Cama
- Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GAUSA
| | - Paul T Cantey
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
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Boussinesq M, Fobi G, Kuesel AC. Alternative treatment strategies to accelerate the elimination of onchocerciasis. Int Health 2018; 10:i40-i48. [PMID: 29471342 PMCID: PMC5881258 DOI: 10.1093/inthealth/ihx054] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 10/30/2017] [Accepted: 11/14/2017] [Indexed: 02/06/2023] Open
Abstract
The use of alternative (or complementary) treatment strategies (ATSs) i.e. differing from annual community-directed treatment with ivermectin (CDTI) is required in some African foci to eliminate onchocerciasis by 2025. ATSs include vector control, biannual or pluriannual CDTI, better timing of CDTI, community-directed treatment with combinations of currently available anthelminthics or new drugs, and 'test-and-treat' (TNT) strategies requiring diagnosis of infection and/or contraindications to treatment for decisions on who to treat with what regimen. Two TNT strategies can be considered. Loa-first TNT, designed for loiasis-endemic areas and currently being evaluated using a rapid test (LoaScope), consists of identifying individuals with levels of Loa microfilaremia associated with a risk of post-ivermectin severe adverse events to exclude them from ivermectin treatment and in treating the rest (usually >97%) of the population safely. Oncho-first TNT consists of testing community members for onchocerciasis before giving treatment (currently ivermectin or doxycycline) to those who are infected. The choice of the ATS depends on the prevalences and intensities of infection with Onchocerca volvulus and Loa loa and on the relative cost-effectiveness of the strategies for the given epidemiological situation. Modelling can help select the optimal strategies, but field evaluations to determine the relative cost-effectiveness are urgently needed.
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Affiliation(s)
- Michel Boussinesq
- IRD UMI 233-INSERM U1175-Montpellier University, 34394 Montpellier, France
| | - Grace Fobi
- African Programme for Onchocerciasis Control, Ouagadougou, Burkina Faso
| | - Annette C Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, Geneva, Switzerland
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Lagatie O, Verheyen A, Nijs E, Van Dorst B, Batsa Debrah L, Debrah A, Supali T, Sartono E, Stuyver LJ. Evaluation of the Diagnostic Performance of Onchocerca volvulus Linear Epitopes in a Peptide Enzyme-Linked Immunosorbent Assay. Am J Trop Med Hyg 2018; 98:779-785. [PMID: 29313477 PMCID: PMC5930915 DOI: 10.4269/ajtmh.17-0756] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Diagnostic tools for the detection of infection with Onchocerca volvulus are presently limited to microfilaria detection in skin biopsies and serological assessment using the Ov16 immunoglobulin G4 (IgG4) rapid test, both of which have limited sensitivity. We have investigated the diagnostic performance of a peptide enzyme-linked immunosorbent assay (ELISA) based on immunodominant linear epitopes previously discovered. Peptides that were used in these assays were designated O. volvulus motif peptides (OvMP): OvMP-1 (VSV-EPVTTQET-VSV), OvMP-2 (VSV-KDGEDK-VSV), OvMP-3 (VSV-QTSNLD-VSV), and the combination of the latter two, OvMP-23 (VSV-KDGEDK-VSV-QTSNLD-VSV). Sensitivity (O. volvulus infection), specificity (non-helminth infections), and cross-reactivity (helminth infections) were determined using several panels of clinical plasma isolates. OvMP-1 was found to be very sensitive (100%) and specific (98.7%), but showed substantial cross-reactivity with other helminths. Of the other peptides, OvMP-23 was the most promising peptide with a sensitivity of 92.7%, a specificity of 100%, and a cross-reactivity of 6%. It was also demonstrated that these peptides were immunoreactive to IgG but not IgG4, and there is no correlation with the Ov16 IgG4 status, making them promising candidates to complement this already available test. Combination of the Ov16 IgG4 rapid test and OvMP-23 peptide ELISA led to a sensitivity of 97.3% for the detection of O. volvulus infection, without compromising specificity and with minimal impact on cross-reactivity. The available results open the opportunity for a “clinical utility use case” discussion for improved O. volvulus epidemiological mapping.
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Affiliation(s)
- Ole Lagatie
- Janssen Diagnostics, Janssen R&D, Beerse, Belgium
| | - Ann Verheyen
- Janssen Diagnostics, Janssen R&D, Beerse, Belgium
| | - Erik Nijs
- Janssen Diagnostics, Janssen R&D, Beerse, Belgium
| | | | - Linda Batsa Debrah
- Kumasi Centre for Collaborative Research into Tropical medicine, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Alex Debrah
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana
| | - Taniawati Supali
- Department of Parasitology, Faculty of Medicine, Universitas Indonesia, Jakarta, Indonesia
| | - Erliyani Sartono
- Department of Parasitology, Leiden University Medical Center, Leiden, The Netherlands
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Targeting Human Onchocerciasis: Recent Advances Beyond Ivermectin. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2018. [DOI: 10.1016/bs.armc.2018.08.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Kobylinski KC, Escobedo-Vargas KS, López-Sifuentes VM, Durand S, Smith ES, Baldeviano GC, Gerbasi RV, Ballard SB, Stoops CA, Vásquez GM. Ivermectin susceptibility, sporontocidal effect, and inhibition of time to re-feed in the Amazonian malaria vector Anopheles darlingi. Malar J 2017; 16:474. [PMID: 29162101 PMCID: PMC5696779 DOI: 10.1186/s12936-017-2125-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/16/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Outdoor malaria transmission hinders malaria elimination efforts in the Amazon region and novel vector control tools are needed. Ivermectin mass drug administration (MDA) to humans kills wild Anopheles, targets outdoor-feeding vectors, and can suppress malaria parasite transmission. Laboratory investigations were performed to determine ivermectin susceptibility, sporontocidal effect and inhibition of time to re-feed for the primary Amazonian malaria vector, Anopheles darlingi. METHODS To assess ivermectin susceptibility, various concentrations of ivermectin were mixed in human blood and fed to An. darlingi. Mosquito survival was monitored daily for 7 days and a non-linear mixed effects model with Probit analysis was used to calculate lethal concentrations of ivermectin that killed 50% (LC50), 25% (LC25) and 5% (LC5) of mosquitoes. To examine ivermectin sporonticidal effect, Plasmodium vivax blood samples were collected from malaria patients and offered to mosquitoes without or with ivermectin at the LC50, LC25 or LC5. To assess ivermectin inhibition of mosquito time to re-feed, concentrations of ivermectin predicted to occur after a single oral dose of 200 μg/kg ivermectin were fed to An. darlingi. Every day for 12 days thereafter, individual mosquitoes were given the opportunity to re-feed on a volunteer. Any mosquitoes that re-blood fed or died were removed from the study. RESULTS Ivermectin significantly reduced An. darlingi survivorship: 7-day-LC50 = 43.2 ng/ml [37.5, 48.6], -LC25 = 27.8 ng/ml [20.4, 32.9] and -LC5 = 14.8 ng/ml [7.9, 20.2]. Ivermectin compound was sporontocidal to P. vivax in An. darlingi at the LC50 and LC25 concentrations reducing prevalence by 22.6 and 17.1%, respectively, but not at the LC5. Oocyst intensity was not altered at any concentration. Ivermectin significantly delayed time to re-feed at the 4-h (48.7 ng/ml) and 12-h (26.9 ng/ml) concentrations but not 36-h (10.6 ng/ml) or 60-h (6.3 ng/ml). CONCLUSIONS Ivermectin is lethal to An. darlingi, modestly inhibits sporogony of P. vivax, and delays time to re-feed at concentrations found in humans up to 12 h post drug ingestion. The LC50 value suggests that a higher than standard dose (400-μg/kg) is necessary to target An. darlingi. These results suggest that ivermectin MDA has potential in the Amazon region to aid malaria elimination efforts.
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Affiliation(s)
- Kevin C Kobylinski
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand. .,Entomology Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA.
| | - Karín S Escobedo-Vargas
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Victor M López-Sifuentes
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Salomón Durand
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Edward S Smith
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - G Christian Baldeviano
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Robert V Gerbasi
- Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, 20910, USA
| | - Sara-Blythe Ballard
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Rm. W5515, Baltimore, MD, 21205, USA
| | - Craig A Stoops
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Gissella M Vásquez
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
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Pilotte N, Unnasch TR, Williams SA. The Current Status of Molecular Xenomonitoring for Lymphatic Filariasis and Onchocerciasis. Trends Parasitol 2017; 33:788-798. [PMID: 28756911 DOI: 10.1016/j.pt.2017.06.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/19/2017] [Accepted: 06/21/2017] [Indexed: 10/19/2022]
Abstract
The capacity of vector insect surveillance to provide estimates of pathogen prevalence and transmission potential has long been recognized within the global communities tasked with eliminating lymphatic filariasis (LF), the underlying cause of elephantiasis and hydrocele, and onchocerciasis (river blindness). Initially restricted to the practice of dissection, the potential of vector monitoring has grown due to the advent of molecular methods capable of increasing the sensitivity and throughput of testing. However, despite such advancement, operational research gaps remain. If insufficiently addressed, these gaps will reduce the utility of molecular xenomonitoring (MX) for onchocerciasis as elimination efforts expand into Africa. Similarly, such shortcomings will limit the programmatic usefulness of MX for LF, resulting in this technique's significant underutilization.
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Affiliation(s)
- Nils Pilotte
- Department of Biological Sciences, Smith College, Northampton, MA, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA, USA; These authors contributed equally to this work
| | - Thomas R Unnasch
- Department of Global Health, University of South Florida, Tampa, FL, USA; These authors contributed equally to this work
| | - Steven A Williams
- Department of Biological Sciences, Smith College, Northampton, MA, USA; Molecular and Cellular Biology Program, University of Massachusetts, Amherst, MA, USA.
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Rodríguez-Pérez MA, Garza-Hernández JA, Salinas-Carmona MC, Fernández-Salas I, Reyes-Villanueva F, Real-Najarro O, Cupp EW, Unnasch TR. The esperanza window trap reduces the human biting rate of Simulium ochraceum s.l. in formerly onchocerciasis endemic foci in Southern Mexico. PLoS Negl Trop Dis 2017; 11:e0005686. [PMID: 28686665 PMCID: PMC5517070 DOI: 10.1371/journal.pntd.0005686] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Revised: 07/19/2017] [Accepted: 06/07/2017] [Indexed: 11/18/2022] Open
Abstract
Background The Esperanza Window Trap (EWT) baited with CO2 and human sweat compounds is attractive to Simulium ochraceum s.l., the primary vector of Onchocerca volvulus in the historically largest endemic foci in México and Guatemala. Methodology/Principal findings The ability of the EWT to locally reduce numbers of questing S. ochraceum s.l. was evaluated in two formerly onchocerciasis endemic communities in Southern México. At each community, two EWTs were placed in or near a school or household and flies were collected sequentially for a total of 10 days. Black fly collections were then carried out for an additional 10 days in the absence of the EWTs. Flies were also collected outside the dwellings to control for variations in the local fly populations. When the EWTs were present, there was a significant reduction in the human biting rate at both the household and school locations at collection sites, with a greater effect observed in the schools. Conclusions/Significance These results indicate that the EWTs not only have potential as a black fly monitoring tool but may be used for reducing personal exposure to fly bites in Mesoamerica. The Esperanza window trap (EWT), when used in large numbers (3-4/household and >90% coverage) and baited with human sweat compounds and CO2, can be used to collect epidemiologically significant numbers of Simulium ochraceum s.l., the primary vector of Onchocerca volvulus in the historically largest endemic foci in México and Guatemala. In the present study, we evaluated the ability of the EWT to reduce the personal biting rate by questing S. ochraceum s.l. in two formerly onchocerciasis endemic communities in Southern México. At each community, two EWTs were placed in or near a school or household and flies were collected sequentially for a total of 10 days. Black fly collections were then carried out for an additional 10 days in the absence of the EWTs. When the EWTs were present, there was a significant reduction in the human biting rate at each of the four collection sites, varying from 14% to 51%. This study demonstrates that the EWTs have potential both as a black fly monitoring and personal exposure reduction tool in Mesoamerica.
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Affiliation(s)
- Mario A. Rodríguez-Pérez
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México
- * E-mail: ,
| | - Javier A. Garza-Hernández
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Reynosa, Tamaulipas, México
- Laboratorio de Biologia Molecular, Universidad Autonoma Agraria Antonio Narro, Unidad Laguna, Torreon, Coahuila. C. P., México
| | | | - Ildefonso Fernández-Salas
- Centro Regional de Investigación en Salud Pública, Instituto Nacional de Salud Pública, Tapachula, Chiapas, México
| | | | - Olga Real-Najarro
- Consejería de Educación, Madrid, España. Calle Maestro 19, Leganés (Madrid) Madrid, España
| | - Eddie W. Cupp
- Department of Entomology and Plant Pathology, Auburn University, Auburn, Alabama, United States of America
| | - Thomas R. Unnasch
- Global Health Infectious Disease Research Program, Department of Global Health, University of South Florida, Tampa, Florida, United States of America
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Babalola OE, Bassi A. Impact assessment study after 27 years of community-directed treatment with ivermectin in Galadimawa, Kaduna State, Nigeria. Niger Postgrad Med J 2017; 24:14-19. [PMID: 28492204 DOI: 10.4103/npmj.npmj_6_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
PURPOSE To assess the impact on blindness after 27 years of community-directed treatment with ivermectin (CDTI) in the Galadimawa community of Kauru Local Government in Kaduna state, Nigeria. The population of Galadimawa constituted about 12% of the total population examined during the ivermectin randomised control trial (RCT) in 1989. The RCT population of 8000 individuals was scattered over 36 villages in Kaduna state. Thus, longitudinal data are available on blindness. MATERIALS AND METHODS After 27 years of dosing with ivermectin, the people in the community of Galadimawa were re-examined for the prevalence and causes of blindness. This was achieved by an examination of the visually disabled. The findings were compared with the situation in 1989 before the dosing commenced. RESULTS The population of the village increased from 711 to 1419. The prevalence of blindness dropped from 4.9 to 0.96%. The most common causes of blindness were now cataract (55.2%) and optic atrophy (27.6%), whereas the most common causes in 1989 were onchocerciasis (28.3%), glaucoma (17.4%) and cataract (10.9%). People with optic atrophy were more likely to have taken fewer doses of ivermectin over the years. The blind people encountered in 2016 were on average 17 years older than those seen in 1989, which suggests that blindness, when it occurs, is delayed by almost two decades. CONCLUSION CDTI has reduced the prevalence of blindness significantly in Galadimawa and may reflect the situation elsewhere in the Kaduna state, which is an oncho-endemic zone.
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Affiliation(s)
- Olufemi E Babalola
- Department of Surgery, College of Health Sciences, Bingham University, Jos; Rachel Eye Center, Garki, Abuja, Nigeria
| | - Amos Bassi
- Department of Community Medicine, College of Health Sciences, Bingham University, Jos, Nigeria
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Affiliation(s)
- Sara Lustigman
- Molecular Parasitology, New York Blood Center, New York, NY, United States of America
- * E-mail:
| | - Alexandra Grote
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, United States of America
| | - Elodie Ghedin
- Center for Genomics and Systems Biology, Department of Biology, New York University, New York, NY, United States of America
- College of Global Public Health, New York University, New York, NY, United States of America
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Cheke RA. Factors affecting onchocerciasis transmission: lessons for infection control. Expert Rev Anti Infect Ther 2017; 15:377-386. [PMID: 28117596 DOI: 10.1080/14787210.2017.1286980] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Onchocerca volvulus infects in excess of 15 million people. The vectors are Simulium blackflies, varieties of which differ in their ecologies, behavior and vectorial abilities. Control of the vectors and mass administrations of ivermectin have succeeded in reducing prevalences with elimination achieved in some foci, particularly in Central and southern America. In Africa, progress towards elimination has been less successful. Areas covered: Even with community directed treatment with ivermectin (CDTI), control has been difficult in African areas with initial prevalences in excess of 55%, especially if only annual treatments are dispensed. This is partly attributable to insufficient coverage, but the appearance of incipiently resistant non-responding parasites and lack of attention to vector biology in modeling and planning outcomes of intervention programmes have also played their parts, with recrudescence now appearing in some treated areas. Expert commentary: The biology of onchocerciasis is complex involving different vectors with differing abilities to transmit parasites, diverse pathologies related to geographical and parasite variations and endosymbionts in both parasite and vector. Modeling to predict epidemiological and control outcomes is addressing this complexity but more attention needs to be given to the vectors' roles to further understanding of where and when control measures will succeed.
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Affiliation(s)
- Robert A Cheke
- a Agriculture, Health and Environment Department, Natural Resources Institute , University of Greenwich at Medway , Kent , UK.,b Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus) , Imperial College London , London , UK
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Abstract
The concept of neglected tropical diseases (NTDs) emerged more than a decade ago and has been recognised as a valid way to categorise diseases that affect the poorest individuals. Substantial progress in control and elimination has been achieved and policy momentum has been generated through continued bilateral, philanthropic, and non-governmental development organisation (NGDO) support, and donations of drugs from pharmaceutical companies. WHO has defined a Roadmap to reach 2020 targets, which was endorsed by member states in a World Health Assembly Resolution in 2013. NTDs have been included within the Sustainable Development Goal targets and are a crucial component of universal health coverage, conceptualised as "leaving no one behind". WHO reported that more than 1 billion people in 88 countries have benefited from preventive chemotherapy in 2014. The research agenda has defined the need for affordable products (diagnostics, drugs and insecticides). However challenges such as insecurity and weak health systems continue to prevail in the poorest countries, inhibiting progress in scaling up and also in achieving Roadmap goals.
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Affiliation(s)
- David H Molyneux
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - Lorenzo Savioli
- Global Schistosomiasis Alliance, Chavannes de Bogis, Switzerland
| | - Dirk Engels
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
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Kamga GR, Dissak-Delon FN, Nana-Djeunga HC, Biholong BD, Mbigha-Ghogomu S, Souopgui J, Zoure HGM, Boussinesq M, Kamgno J, Robert A. Still mesoendemic onchocerciasis in two Cameroonian community-directed treatment with ivermectin projects despite more than 15 years of mass treatment. Parasit Vectors 2016; 9:581. [PMID: 27842567 PMCID: PMC5109673 DOI: 10.1186/s13071-016-1868-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 11/02/2016] [Indexed: 11/10/2022] Open
Abstract
Background After more than a decade of community-directed treatment with ivermectin (CDTI) in Centre and Littoral Regions of Cameroon, onchocerciasis endemicity was still high in some communities according to the 2011 epidemiological evaluations. Some corrective measures were undertaken to improve the CDTI process and therefore reduce the burden of the disease. The objective of the present study was to assess the progress made towards the elimination of onchocerciasis in the Centre 1 and Littoral 2 CDTI projects where the worst performances were found in 2011. To this end, a cross-sectional survey was conducted in April 2015 in eight communities in two health districts (HD), Bafia in Centre 1 and Yabassi in Littoral 2, chosen because assessed at baseline and in 2011. All volunteers living for at least five years in the community, aged five years or more, underwent clinical and parasitological examinations. Individual compliance to ivermectin treatment was also assessed. Analyses of data were weighted proportionally to age and gender distribution in the population. Results In the Bafia and Yabassi HD, 514 and 242 individuals were examined with a mean age of 35.1 (standard deviation, SD: 20.7) and 44.6 (SD: 16.3) years, respectively. In the Bafia HD, the weighted prevalences varied from 24.4 to 57.0 % for microfilaridermia and from 3.6 to 37.4 % for nodule presence across the surveyed communities. The community microfilarial load (CMFL), expressed in microfilariae/skin snip (mf/ss), significantly dropped from 20.84–114.50 mf/ss in 1991 to 0.31–1.62 mf/ss in 2015 in all the surveyed communities. In the Yabassi HD, the weighted prevalences varied from 12.3 to 59.3 % for microfilaridermia and from 1.5 to 3.7 % for nodule presence across the surveyed communities, while a significant drop was observed in CMFL, from 20.40–28.50 mf/ss in 1999 to 0.48–1.74 mf/ss in 2015. The 2014 weighted therapeutic coverage of participants varied from 65.8 % (95 % CI: 58.4–73.2) in Yabassi HD, to 68.0 % (95 % CI: 63.3–72.7) in Bafia HD, with important variations among communities. Conclusions After more than 15 years of CDTI, onchocerciasis is still mesoendemic in the surveyed communities. Further studies targeting therapeutic coverage, socio-anthropological considerations of CDTI implementation and entomological studies would bring more insights to the persistence of the disease as observed in the present study. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1868-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Guy-Roger Kamga
- Ministry of Public Health, N°8, Rue 3038 quartier du Lac, Yaoundé, Cameroon. .,Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), P.O. Box 5797, Yaoundé, Cameroon. .,Institut de Recherche Expérimentale et Clinique, Faculté de santé publique, Université catholique de Louvain, Clos Chapelle-aux-champs 30 bte B1.30.13 BE-1200, Brussels, Belgium.
| | - Fanny N Dissak-Delon
- Ministry of Public Health, N°8, Rue 3038 quartier du Lac, Yaoundé, Cameroon.,Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), P.O. Box 5797, Yaoundé, Cameroon.,Institute of Biology of Molecular Medicine, Université Libre de Bruxelles, Rue des professeurs Jeener et Brachet 12 BE-6041 Gosselies, Brussels, Belgium
| | - Hugues C Nana-Djeunga
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), P.O. Box 5797, Yaoundé, Cameroon.,Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, P.O. Box 1364, Yaoundé, Cameroon
| | | | - Stephen Mbigha-Ghogomu
- Molecular and Cell Biology Laboratory, Department of Biochemistry and Molecular Biology, University of Buea, P.O. Box 63, Buea, Cameroon
| | - Jacob Souopgui
- Institute of Biology of Molecular Medicine, Université Libre de Bruxelles, Rue des professeurs Jeener et Brachet 12 BE-6041 Gosselies, Brussels, Belgium
| | - Honorat G M Zoure
- World Health Organization, African Programme for Onchocerciasis Control (APOC), 01 P.O. Box 549, Ouagadougou 01, Burkina Faso
| | - Michel Boussinesq
- Institut de Recherche pour le Développement (IRD), IRD UMI 233 TransVIHMI - Université Montpellier - INSERM U1175, 911 avenue Agropolis, P.O. Box 64501, 34394, Montpellier Cedex 5, France
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), P.O. Box 5797, Yaoundé, Cameroon.,Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, P.O. Box 1364, Yaoundé, Cameroon
| | - Annie Robert
- Institut de Recherche Expérimentale et Clinique, Faculté de santé publique, Université catholique de Louvain, Clos Chapelle-aux-champs 30 bte B1.30.13 BE-1200, Brussels, Belgium
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Kazura JW. Onchocerciasis Elimination from Africa: One Step in Northern Sudan. Am J Trop Med Hyg 2016; 95:983-984. [PMID: 27698270 PMCID: PMC5094246 DOI: 10.4269/ajtmh.16-0684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 08/24/2016] [Indexed: 11/07/2022] Open
Affiliation(s)
- James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University School of Medicine, Cleveland, Ohio
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Hernández-González A, Moya L, Perteguer MJ, Herrador Z, Nguema R, Nguema J, Aparicio P, Benito A, Gárate T. Evaluation of onchocerciasis seroprevalence in Bioko Island (Equatorial Guinea) after years of disease control programmes. Parasit Vectors 2016; 9:509. [PMID: 27645887 PMCID: PMC5028998 DOI: 10.1186/s13071-016-1779-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Accepted: 08/29/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Onchocerciasis or "river blindness" is a chronic parasitic disease caused by the filarial worm Onchocerca volvulus, transmitted through infected blackflies (Simulium spp.). Bioko Island (Equatorial Guinea) used to show a high endemicity for onchocerciasis. During the last years, the disease control programmes using different larvicides and ivermectin administration have considerably reduced the prevalence and intensity of infection. Based on this new epidemiological scenario, in the present work we aimed to assess the impact of the strategies applied against onchocerciasis in Bioko Island by an evaluation of IgG4 antibodies specific for recombinant Ov-16 in ELISA. METHODS A cross-sectional study was conducted in Bioko Island from mid-January to mid-February, 2014. Twenty communities were randomly selected from rural and urban settings. A total of 140 households were chosen. In every selected household, all individuals aged 5 years and above were recruited; 544 study participants agreed to be part of this work. No previous data on onchocerciasis seroprevalence in the selected communities were available. Blood samples were collected and used in an "ELISA in-house" prepared with recombinant Ov-16, expressed and further purified. IgG4 antibodies specific for recombinant Ov-16 were evaluated by ELISA in all of the participants. RESULTS Based on the Ov-16 ELISA, the onchocerciasis seroprevalence was 7.9 %, mainly concentrated in rural settings; samples from community Catedral Ela Nguema (# 16) were missed during the field work. Among the rural setups, communities Inasa Maule (# 7), Ruiché (# 20) and Barrios Adyacentes Riaba (# 14), had the highest seropositivity percentages (29.2, 26.9 and 23.8 %, respectively). With respect to the urban settings, we did not find any positive case in communities Manzana Casa Bola (# 3), Colas Sesgas (# 6), Getesa (# 8), Moka Bioko (# 9), Impecsa (# 10), Baney Zona Baja (# 12) and Santo Tomás de Aquino (# 1). No onchocerciasis seropositive samples were found in 10-year-old individuals or younger. The IgG4 positive titles increased in older participants. CONCLUSIONS A significant decline in onchocerciasis prevalence was observed in Bioko Island after years of disease-vector control and CDTI strategy. The seroprevalence increased with age, mainly in rural settings that could be due to previous exposure of population to the filarial parasite, eliminated by the control programmes introduced against onchocerciasis. A new Ov-16 serological evaluation with a larger sample size of children below 10 years of age is required to demonstrate the interruption of transmission of O. volvulus in the human population of Bioko Island (Equatorial Guinea) according to the WHO criteria.
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Affiliation(s)
- Ana Hernández-González
- Helminth Unit, Parasitology Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Crtra. Majadahonda-Pozuelo, km 2.2, 28220, Majadahonda, Madrid, Spain.,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain
| | - Laura Moya
- National Centre for Tropical Medicine, Instituto de Salud Carlos III, C/ Sinesio Delgado, 4, 28029, Madrid, Spain.,Jimenez Diaz Foundation University Hospital, Avda. Reyes Católicos, 2, 28040, Madrid, Spain
| | - María J Perteguer
- Helminth Unit, Parasitology Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Crtra. Majadahonda-Pozuelo, km 2.2, 28220, Majadahonda, Madrid, Spain.,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain
| | - Zaida Herrador
- National Centre for Tropical Medicine, Instituto de Salud Carlos III, C/ Sinesio Delgado, 4, 28029, Madrid, Spain.,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain
| | - Rufino Nguema
- Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain.,National Program for Control of Onchocerciasis and other Filariasis, Ministry of Health, Malabo, Equatorial Guinea
| | - Justino Nguema
- Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain.,National Program for Control of Onchocerciasis and other Filariasis, Ministry of Health, Malabo, Equatorial Guinea
| | - Pilar Aparicio
- National Centre for Tropical Medicine, Instituto de Salud Carlos III, C/ Sinesio Delgado, 4, 28029, Madrid, Spain.,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain
| | - Agustín Benito
- National Centre for Tropical Medicine, Instituto de Salud Carlos III, C/ Sinesio Delgado, 4, 28029, Madrid, Spain.,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain
| | - Teresa Gárate
- Helminth Unit, Parasitology Department, Centro Nacional de Microbiología, Instituto de Salud Carlos III, Crtra. Majadahonda-Pozuelo, km 2.2, 28220, Majadahonda, Madrid, Spain. .,Network Biomedical Research on Tropical Diseases (RICET), Madrid, Spain.
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Golden A, Faulx D, Kalnoky M, Stevens E, Yokobe L, Peck R, Karabou P, Banla M, Rao R, Adade K, Gantin RG, Komlan K, Soboslay PT, de Los Santos T, Domingo GJ. Analysis of age-dependent trends in Ov16 IgG4 seroprevalence to onchocerciasis. Parasit Vectors 2016; 9:338. [PMID: 27296630 PMCID: PMC4907250 DOI: 10.1186/s13071-016-1623-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 06/02/2016] [Indexed: 11/30/2022] Open
Abstract
Background Diagnostics provide a means to measure progress toward disease elimination. Many countries in Africa are approaching elimination of onchocerciasis after successful implementation of mass drug administration programs as well as vector control. An understanding of how markers for infection such as skin snip microfilaria and Onchocerca volvulus-specific seroconversion perform in near-elimination settings informs how to best use these markers. Methods All-age participants from 35 villages in Togo were surveyed in 2013 and 2014 for skin snip Onchocerca volvulus microfilaria and IgG4 antibody response by enzyme-linked immunosorbent assay (ELISA) to the Onchocerca volvulus-specific antigen Ov16. A Gaussian mixture model applying the expectation-maximization (EM) algorithm was used to determine seropositivity from Ov16 ELISA data. For a subset of participants (n = 434), polymerase chain reaction (PCR) was performed on the skin snips taken during surveillance. Results Within the 2,005 participants for which there was Ov16 ELISA data, O. volvulus microfilaremia prevalence and Ov16 seroprevalence were, 2.5 and 19.7 %, respectively, in the total population, and 1.6 and 3.6 % in children under 11. In the subset of 434 specimens for which ELISA, PCR, and microscopy data were generated, it was found that in children under 11 years of age, the anti-Ov16 IgG4 antibody response demonstrate a sensitivity and specificity of 80 and 97 %, respectively, against active infections as determined by combined PCR and microscopy on skin snips. Further analysis was performed in 34 of the 35 villages surveyed. These villages were stratified by all-age seroprevalence into three clusters: < 15 %; 15–20 %; and > 20 %. Age-dependence of seroprevalence for each cluster was best reflected by a two-phase force-of-infection (FOI) catalytic model. In all clusters, the lower of the two phases of FOI was associated with a younger age group, as reflected by the seroconversion rates for each phase. The age at which transition from lower to higher seroconversion, between the two phases of FOI, was found to be highest (older) for the cluster of villages with < 15 % seroprevalence and lowest (younger) for the cluster with the highest all-age seroprevalence. Conclusions The anti-Ov16 IgG4 antibody response is an accurate marker for active infection in children under 11 years of age in this population. Applying Ov16 surveillance to a broader age range provides additional valuable information for understanding progression toward elimination and can inform where targeted augmented interventions may be needed. Clustering of villages by all-age sero-surveillance allowed application of a biphasic FOI model to differentiate seroconversion rates for different age groups within the village cluster categories. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1623-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Dunia Faulx
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Eric Stevens
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Roger Peck
- Diagnostics Global Program, PATH, Seattle, WA, USA
| | | | - Méba Banla
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | | | - Kangi Adade
- National Onchocerciasis Control Programme, Kara, Togo
| | - Richard G Gantin
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | - Kossi Komlan
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo
| | - Peter T Soboslay
- Onchocerciasis Reference Laboratory, National Institute of Hygiene, Sokodé, Togo.,Institute of Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
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Kuesel AC. Research for new drugs for elimination of onchocerciasis in Africa. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2016; 6:272-286. [PMID: 27693536 PMCID: PMC5196484 DOI: 10.1016/j.ijpddr.2016.04.002] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/20/2016] [Indexed: 01/12/2023]
Abstract
Onchocerciasis is a parasitic, vector borne disease caused by the filarial nematode Onchocerca volvulus. More than 99% of the population at risk of infection live in Africa. Onchocerciasis control was initiated in West Africa in 1974 with vector control, later complemented by ivermectin mass drug administration and in the other African endemic countries in 1995 with annual community directed treatment with ivermectin (CDTI.) This has significantly reduced infection prevalence. Together with proof-of-concept for onchocerciasis elimination with annual CDTI from foci in Senegal and Mali, this has resulted in targeting onchocerciasis elimination in selected African countries by 2020 and in 80% of African countries by 2025. The challenges for meeting these targets include the number of endemic countries where conflict has delayed or interrupted control programmes, cross-border foci, potential emergence of parasite strains with low susceptibility to ivermectin and co-endemicity of loiasis, another parasitic vector borne disease, which slows down or prohibits CDTI implementation. Some of these challenges could be addressed with new drugs or drug combinations with a higher effect on Onchocerca volvulus than ivermectin. This paper reviews the path from discovery of new compounds to their qualification for large scale use and the support regulatory authorities provide for development of drugs for neglected tropical diseases. The status of research for new drugs or treatment regimens for onchocerciasis along the path to regulatory approval and qualification for large scale use is reviewed. This research includes new regimens and combinations of ivermectin and albendazole, antibiotics targeting the O. volvulus endosymbiont Wolbachia, flubendazole, moxidectin and emodepside and discovery of new compounds.
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Affiliation(s)
- Annette C Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases, 20 Avenue Appia, 1211 Geneva, Switzerland.
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Frempong KK, Walker M, Cheke RA, Tetevi EJ, Gyan ET, Owusu EO, Wilson MD, Boakye DA, Taylor MJ, Biritwum NK, Osei-Atweneboana M, Basáñez MG. Does Increasing Treatment Frequency Address Suboptimal Responses to Ivermectin for the Control and Elimination of River Blindness? Clin Infect Dis 2016; 62:1338-1347. [PMID: 27001801 PMCID: PMC4872292 DOI: 10.1093/cid/ciw144] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 03/10/2016] [Indexed: 11/18/2022] Open
Abstract
The first 3 years of biannual ivermectin distribution in Ghana have substantially reduced Onchocerca volvulus infection levels in 10 sentinel communities, but longitudinal analysis indicates that some communities are still consistently responding suboptimally to treatment, with implications for onchocerciasis elimination. Background. Several African countries have adopted a biannual ivermectin distribution strategy in some foci to control and eliminate onchocerciasis. In 2010, the Ghana Health Service started biannual distribution to combat transmission hotspots and suboptimal responses to treatment. We assessed the epidemiological impact of the first 3 years of this strategy and quantified responses to ivermectin over 2 consecutive rounds of treatment in 10 sentinel communities. Methods. We evaluated Onchocerca volvulus community microfilarial intensity and prevalence in persons aged ≥20 years before the first, second, and fifth (or sixth) biannual treatment rounds using skin snip data from 956 participants. We used longitudinal regression modeling to estimate rates of microfilarial repopulation of the skin in a cohort of 217 participants who were followed up over the first 2 rounds of biannual treatment. Results. Biannual treatment has had a positive impact, with substantial reductions in infection intensity after 4 or 5 rounds in most communities. We identified 3 communities—all having been previously recognized as responding suboptimally to ivermectin—with statistically significantly high microfilarial repopulation rates. We did not find any clear association between microfilarial repopulation rate and the number of years of prior intervention, coverage, or the community level of infection. Conclusions. The strategy of biannual ivermectin treatment in Ghana has reduced O. volvulus microfilarial intensity and prevalence, but suboptimal responses to treatment remain evident in a number of previously and consistently implicated communities. Whether increasing the frequency of treatment will be sufficient to meet the World Health Organization's 2020 elimination goals remains uncertain.
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Affiliation(s)
- Kwadwo K Frempong
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London
| | - Robert A Cheke
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London.,Natural Resources Institute, University of Greenwich at Medway, Chatham Maritime, United Kingdom
| | | | - Ernest Tawiah Gyan
- Council for Scientific and Industrial Research, Water Research Institute, Accra
| | - Ebenezer O Owusu
- Department of Animal Biology and Conservation Science, University of Ghana, Legon
| | - Michael D Wilson
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Daniel A Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon
| | - Mark J Taylor
- Department of Parasitology, Liverpool School of Tropical Medicine, United Kingdom
| | | | | | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London
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Botto C, Basañez MG, Escalona M, Villamizar NJ, Noya-Alarcón O, Cortez J, Vivas-Martínez S, Coronel P, Frontado H, Flores J, Graterol B, Camacho O, Tovar Y, Borges D, Morales AL, Ríos D, Guerra F, Margeli H, Rodriguez MA, Unnasch TR, Grillet ME. Evidence of suppression of onchocerciasis transmission in the Venezuelan Amazonian focus. Parasit Vectors 2016; 9:40. [PMID: 26813296 PMCID: PMC4728794 DOI: 10.1186/s13071-016-1313-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 01/11/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The World Health Organization (WHO) has set goals for onchocerciasis elimination in Latin America by 2015. Most of the six previously endemic countries are attaining this goal by implementing twice a year (and in some foci, quarterly) mass ivermectin (Mectizan®) distribution. Elimination of transmission has been verified in Colombia, Ecuador and Mexico. Challenges remain in the Amazonian focus straddling Venezuela and Brazil, where the disease affects the hard-to-reach Yanomami indigenous population. We provide evidence of suppression of Onchocerca volvulus transmission by Simulium guianense s.l. in 16 previously hyperendemic Yanomami communities in southern Venezuela after 15 years of 6-monthly and 5 years of 3-monthly mass ivermectin treatment. METHODS Baseline and monitoring and evaluation parasitological, ophthalmological, entomological and serological surveys were conducted in selected sentinel and extra-sentinel communities of the focus throughout the implementation of the programme. RESULTS From 2010 to 2012-2015, clinico-parasitological surveys indicate a substantial decrease in skin microfilarial prevalence and intensity of infection; accompanied by no evidence (or very low prevalence and intensity) of ocular microfilariae in the examined population. Of a total of 51,341 S. guianense flies tested by PCR none had L3 infection (heads only). Prevalence of infective flies and seasonal transmission potentials in 2012-2013 were, respectively, under 1% and 20 L3/person/transmission season. Serology in children aged 1-10 years demonstrated that although 26 out of 396 (7%) individuals still had Ov-16 antibodies, only 4/218 (2%) seropositives were aged 1-5 years. CONCLUSIONS We report evidence of recent transmission and morbidity suppression in some communities of the focus representing 75% of the Yanomami population and 70% of all known communities. We conclude that onchocerciasis transmission could be feasibly interrupted in the Venezuelan Amazonian focus.
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Affiliation(s)
- Carlos Botto
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - María-Gloria Basañez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine (St Mary's campus), Imperial College London, London, UK.
| | - Marisela Escalona
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Néstor J Villamizar
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Oscar Noya-Alarcón
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
- Instituto de Medicina Tropical, Facultad de Medicina, Universidad Central de Venezuela, Caracas, Venezuela.
| | - José Cortez
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Sarai Vivas-Martínez
- Cátedra de Salud Pública. Facultad de Medicina (Escuela Luis Razetti), Universidad Central de Venezuela, Caracas, Venezuela.
| | - Pablo Coronel
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Hortencia Frontado
- Instituto de Altos Estudios "Dr. Arnoldo Gabaldón", Ministerio del Poder Popular para la Salud, Maracay, Estado Aragua, Venezuela.
| | - Jorge Flores
- Instituto Geográfico de Venezuela "Simón Bolívar", Caracas, Venezuela.
| | - Beatriz Graterol
- Instituto Nacional de Investigaciones Agrícolas, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Oneida Camacho
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Yseliam Tovar
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Daniel Borges
- Centro Amazónico de Investigación y Control de Enfermedades Tropicales Servicio Autónomo CAICET, Ministerio del Poder Popular para la Salud, Puerto Ayacucho, Estado Amazonas, Venezuela.
| | - Alba Lucia Morales
- Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala.
| | - Dalila Ríos
- Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala.
| | - Francisco Guerra
- Instituto Geográfico de Venezuela "Simón Bolívar", Caracas, Venezuela.
| | - Héctor Margeli
- Onchocerciasis Elimination Program for the Americas (OEPA), Guatemala City, Guatemala.
| | | | - Thomas R Unnasch
- Department of Global Health, University of South Florida, Tampa, FL, USA.
| | - María Eugenia Grillet
- Laboratorio de Biología de Vectores y Parásitos, Instituto de Zoología y Ecología Tropical, Facultad de Ciencias, Universidad Central de Venezuela, Apartado Postal 47072, Caracas, 1041-A, Venezuela.
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Basáñez M, Walker M, Turner H, Coffeng L, de Vlas S, Stolk W. River Blindness: Mathematical Models for Control and Elimination. ADVANCES IN PARASITOLOGY 2016; 94:247-341. [PMID: 27756456 DOI: 10.1016/bs.apar.2016.08.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Human onchocerciasis (river blindness) is one of the few neglected tropical diseases (NTDs) whose control strategies have been informed by mathematical modelling. With the change in focus from elimination of the disease burden to elimination of Onchocerca volvulus, much remains to be done to refine, calibrate and validate existing models. Under the impetus of the NTD Modelling Consortium, the teams that developed EPIONCHO and ONCHOSIM have joined forces to compare and improve these frameworks to better assist ongoing elimination efforts. We review their current versions and describe how they are being used to address two key questions: (1) where can onchocerciasis be eliminated with current intervention strategies by 2020/2025? and (2) what alternative/complementary strategies could help to accelerate elimination where (1) cannot be achieved? The control and elimination of onchocerciasis from the African continent is at a crucial crossroad. The African Programme for Onchocerciasis Control closed at the end of 2015, and although a new platform for support and integration of NTD control has been launched, the disease will have to compete with a myriad of other national health priorities at a pivotal time in the road to elimination. However, never before had onchocerciasis control a better arsenal of intervention strategies as well as diagnostics. It is, therefore, timely to present two models of different geneses and modelling traditions as they come together to produce robust decision-support tools. We start by describing the structural and parametric assumptions of EPIONCHO and ONCHOSIM; we continue by summarizing the modelling of current treatment strategies with annual (or biannual) mass ivermectin distribution and introduce a number of alternative strategies, including other microfilaricidal therapies (such as moxidectin), macrofilaricidal (anti-wolbachial) treatments, focal vector control and the possibility of an onchocerciasis vaccine. We conclude by discussing challenges, opportunities and future directions.
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Hollingsworth TD, Adams ER, Anderson RM, Atkins K, Bartsch S, Basáñez MG, Behrend M, Blok DJ, Chapman LAC, Coffeng L, Courtenay O, Crump RE, de Vlas SJ, Dobson A, Dyson L, Farkas H, Galvani AP, Gambhir M, Gurarie D, Irvine MA, Jervis S, Keeling MJ, Kelly-Hope L, King C, Lee BY, Le Rutte EA, Lietman TM, Ndeffo-Mbah M, Medley GF, Michael E, Pandey A, Peterson JK, Pinsent A, Porco TC, Richardus JH, Reimer L, Rock KS, Singh BK, Stolk W, Swaminathan S, Torr SJ, Townsend J, Truscott J, Walker M, Zoueva A. Quantitative analyses and modelling to support achievement of the 2020 goals for nine neglected tropical diseases. Parasit Vectors 2015; 8:630. [PMID: 26652272 PMCID: PMC4674954 DOI: 10.1186/s13071-015-1235-1] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 12/01/2015] [Indexed: 12/30/2022] Open
Abstract
Quantitative analysis and mathematical models are useful tools in informing strategies to control or eliminate disease. Currently, there is an urgent need to develop these tools to inform policy to achieve the 2020 goals for neglected tropical diseases (NTDs). In this paper we give an overview of a collection of novel model-based analyses which aim to address key questions on the dynamics of transmission and control of nine NTDs: Chagas disease, visceral leishmaniasis, human African trypanosomiasis, leprosy, soil-transmitted helminths, schistosomiasis, lymphatic filariasis, onchocerciasis and trachoma. Several common themes resonate throughout these analyses, including: the importance of epidemiological setting on the success of interventions; targeting groups who are at highest risk of infection or re-infection; and reaching populations who are not accessing interventions and may act as a reservoir for infection,. The results also highlight the challenge of maintaining elimination 'as a public health problem' when true elimination is not reached. The models elucidate the factors that may be contributing most to persistence of disease and discuss the requirements for eventually achieving true elimination, if that is possible. Overall this collection presents new analyses to inform current control initiatives. These papers form a base from which further development of the models and more rigorous validation against a variety of datasets can help to give more detailed advice. At the moment, the models' predictions are being considered as the world prepares for a final push towards control or elimination of neglected tropical diseases by 2020.
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Affiliation(s)
| | - Emily R Adams
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | | | - Katherine Atkins
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Sarah Bartsch
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | | | | | - David J Blok
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Luc Coffeng
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Ron E Crump
- University of Warwick, Coventry, CV4 7AL, UK
| | - Sake J de Vlas
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | - Andy Dobson
- Princeton University, New Jersey, NJ, 08544, USA
| | | | | | | | | | - David Gurarie
- Case Western Reserve University, Cleveland, OH, 44106, USA
| | | | | | | | | | - Charles King
- Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Bruce Y Lee
- Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, 21205, USA
| | - Epke A Le Rutte
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | - Thomas M Lietman
- University of California, San Francisco, San Francisco, CA, 94143, USA
| | | | - Graham F Medley
- London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Edwin Michael
- University of Notre Dame, South Bend, IN, 47556, USA
| | | | | | - Amy Pinsent
- Monash University, Melbourne, VIC, 3800, Australia
| | - Travis C Porco
- University of California, San Francisco, San Francisco, CA, 94143, USA
| | | | - Lisa Reimer
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Kat S Rock
- University of Warwick, Coventry, CV4 7AL, UK
| | | | - Wilma Stolk
- Erasmus University Medical Center, 3015 CE, Rotterdam, Netherlands
| | | | - Steve J Torr
- Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
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Abstract
The twentieth century's arsenal of chemical anthelmintics brought manifold improvement in human health and, more abundantly, in animal health. The benefits were not only in health per se but also in agricultural economics, livestock management, and the overall production of food and fiber to support expanding human populations. Nevertheless, there remains (due in large part to drug resistance and paucity of available vaccines) a great need for new means of controlling disease caused by parasitic worms. Prudence should persuade us to look to our past for lessons that might help in our quest for new drugs. The lessons suggested here derive from the history of ivermectin and other anthelmintics. They deal with the means of finding substances with useful antiparasitic activity and with alternative approaches to drug discovery.
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Affiliation(s)
- William C Campbell
- Research Institute for Scientists Emeriti, Drew University, Madison, New Jersey 07940;
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45
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Stolk WA, Walker M, Coffeng LE, Basáñez MG, de Vlas SJ. Required duration of mass ivermectin treatment for onchocerciasis elimination in Africa: a comparative modelling analysis. Parasit Vectors 2015; 8:552. [PMID: 26489937 PMCID: PMC4618738 DOI: 10.1186/s13071-015-1159-9] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 10/08/2015] [Indexed: 11/16/2022] Open
Abstract
Background The World Health Organization (WHO) has set ambitious targets for the elimination of onchocerciasis by 2020–2025 through mass ivermectin treatment. Two different mathematical models have assessed the feasibility of reaching this goal for different settings and treatment scenarios, namely the individual-based microsimulation model ONCHOSIM and the population-based deterministic model EPIONCHO. In this study, we harmonize some crucial assumptions and compare model predictions on common outputs. Methods Using a range of initial endemicity levels and treatment scenarios, we compared the models with respect to the following outcomes: 1) model-predicted trends in microfilarial (mf) prevalence and mean mf intensity during 25 years of (annual or biannual) mass ivermectin treatment; 2) treatment duration needed to bring mf prevalence below a provisional operational threshold for treatment interruption (pOTTIS, i.e. 1.4 %), and 3) treatment duration needed to drive the parasite population to local elimination, even in the absence of further interventions. Local elimination was judged by stochastic fade-out in ONCHOSIM and by reaching transmission breakpoints in EPIONCHO. Results ONCHOSIM and EPIONCHO both predicted that in mesoendemic areas the pOTTIS can be reached with annual treatment, but that this strategy may be insufficient in very highly hyperendemic areas or would require prolonged continuation of treatment. For the lower endemicity levels explored, ONCHOSIM predicted that the time needed to reach the pOTTIS is longer than that needed to drive the parasite population to elimination, whereas for the higher endemicity levels the opposite was true. In EPIONCHO, the pOTTIS was reached consistently sooner than the breakpoint. Conclusions The operational thresholds proposed by APOC may have to be adjusted to adequately reflect differences in pre-control endemicities. Further comparative modelling work will be conducted to better understand the main causes of differences in model-predicted trends. This is a pre-requisite for guiding elimination programmes in Africa and refining operational criteria for stopping mass treatment. Electronic supplementary material The online version of this article (doi:10.1186/s13071-015-1159-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wilma A Stolk
- 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, Imperial College London, London, UK.
| | - Luc E Coffeng
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
| | - María-Gloria Basáñez
- 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, The Netherlands.
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