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Mutono N, Basáñez MG, James A, Stolk WA, Makori A, Kimani TN, Hollingsworth TD, Vasconcelos A, Dixon MA, de Vlas SJ, Thumbi SM. Elimination of transmission of onchocerciasis (river blindness) with long-term ivermectin mass drug administration with or without vector control in sub-Saharan Africa: a systematic review and meta-analysis. Lancet Glob Health 2024; 12:e771-e782. [PMID: 38484745 PMCID: PMC11009120 DOI: 10.1016/s2214-109x(24)00043-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 01/11/2024] [Accepted: 01/19/2024] [Indexed: 04/15/2024]
Abstract
BACKGROUND WHO has proposed elimination of transmission of onchocerciasis (river blindness) by 2030. More than 99% of cases of onchocerciasis are in sub-Saharan Africa. Vector control and mass drug administration of ivermectin have been the main interventions for many years, with varying success. We aimed to identify factors associated with elimination of onchocerciasis transmission in sub-Saharan Africa. METHODS For this systematic review and meta-analysis we searched for published articles reporting epidemiological or entomological assessments of onchocerciasis transmission status in sub-Saharan Africa, with or without vector control. We searched MEDLINE, PubMed, Web of Science, Embase, Cochrane Central Register of Controlled Trials, African Index Medicus, and Google Scholar databases for all articles published from database inception to Aug 19, 2023, without language restrictions. The search terms used were "onchocerciasis" AND "ivermectin" AND "mass drug administration". The three inclusion criteria were (1) focus or foci located in Africa, (2) reporting of elimination of transmission or at least 10 years of ivermectin mass drug administration in the focus or foci, and (3) inclusion of at least one of the following assessments: microfilarial prevalence, nodule prevalence, Ov16 antibody seroprevalence, and blackfly infectivity prevalence. Epidemiological modelling studies and reviews were excluded. Four reviewers (NM, AJ, AM, and TNK) extracted data in duplicate from the full-text articles using a data extraction tool developed in Excel with columns recording the data of interest to be extracted, and a column where important comments for each study could be highlighted. We did not request any individual-level data from authors. Foci were classified as achieving elimination of transmission, being close to elimination of transmission, or with ongoing transmission. We used mixed-effects meta-regression models to identify factors associated with transmission status. This study is registered in PROSPERO, CRD42022338986. FINDINGS Of 1525 articles screened after the removal of duplicates, 75 provided 282 records from 238 distinct foci in 19 (70%) of the 27 onchocerciasis-endemic countries in sub-Saharan Africa. Elimination of transmission was reported in 24 (9%) records, being close to elimination of transmission in 86 (30%) records, and ongoing transmission in 172 (61%) records. I2 was 83·3% (95% CI 79·7 to 86·3). Records reporting 10 or more years of continuous mass drug administration with 80% or more therapeutic coverage of the eligible population yielded significantly higher odds of achieving elimination of transmission (log-odds 8·5 [95% CI 3·5 to 13·5]) or elimination and being close to elimination of transmission (42·4 [18·7 to 66·1]) than those with no years achieving 80% coverage or more. Reporting 15-19 years of ivermectin mass drug administration (22·7 [17·2 to 28·2]) and biannual treatment (43·3 [27·2 to 59·3]) were positively associated with elimination and being close to elimination of transmission compared with less than 15 years and no biannual mass drug administration, respectively. Having had vector control without vector elimination (-42·8 [-59·1 to -26·5]) and baseline holoendemicity (-41·97 [-60·6 to -23·2]) were associated with increased risk of ongoing transmission compared with no vector control and hypoendemicity, respectively. Blackfly disappearance due to vector control or environmental change contributed to elimination of transmission. INTERPRETATION Mass drug administration duration, frequency, and coverage; baseline endemicity; and vector elimination or disappearance are important determinants of elimination of onchocerciasis transmission in sub-Saharan Africa. Our findings underscore the importance of improving and sustaining high therapeutic coverage and increasing treatment frequency if countries are to achieve elimination of onchocerciasis transmission. FUNDING The Bill & Melinda Gates Foundation and Neglected Tropical Diseases Modelling Consortium, UK Medical Research Council, and Global Health EDCTP3 Joint Undertaking. TRANSLATIONS For the Swahili, French, Spanish and Portuguese translations of the abstract see Supplementary Materials section.
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Affiliation(s)
- Nyamai Mutono
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA.
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Ananthu James
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Wilma A Stolk
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - Anita Makori
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA
| | - Teresia Njoki Kimani
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA; Ministry of Health Kenya, Kiambu Town, Kenya
| | | | | | - Matthew A Dixon
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK; London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, UK
| | - Sake J de Vlas
- Department of Public Health, Erasmus MC, University Medical Center Rotterdam, Rotterdam, Netherlands
| | - S M Thumbi
- Centre for Epidemiological Modelling and Analysis, University of Nairobi, Nairobi, Kenya; Paul G Allen School for Global Health, Washington State University, Pullman, WA, USA; Institute of Immunology and Infection Research, University of Edinburgh, Edinburgh, UK
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Mansour A, Rodriguez L, Mansour H, Yehia M, Battaglia Parodi M. Presumed Onchocerciasis Chorioretinitis Spilling over into North America, Europe and Middle East. Diagnostics (Basel) 2023; 13:3626. [PMID: 38132210 PMCID: PMC10743067 DOI: 10.3390/diagnostics13243626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 11/26/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND Newer generation ophthalmologists practicing in the developed world are not very familiar with some tropical ocular diseases due to the absence of reports in the ophthalmic literature over the past thirty years. Because of world globalization or due to influx of immigrants from sub-Saharan Africa, exotic retinal diseases are being encountered more often in ophthalmology clinics. METHODS A multicenter case series of chorioretinitis or optic neuritis with obscure etiology that used serial multimodal imaging. RESULTS Four cases qualified with the diagnosis of presumed ocular onchocerciasis based on their residence near fast rivers in endemic areas, multimodal imaging, long term follow-up showing progressive disease and negative workup for other diseases. Characteristic findings include peripapillary choroiditis with optic neuritis or atrophy, subretinal tracts of the microfilaria, progressive RPE atrophy around heavily pigmented multifocal chorioretinal lesions of varying shapes, subretinal white or crystalline dots, and response to ivermectin. Typical skin findings are often absent in such patients with chorioretinitis rendering the diagnosis more challenging. CONCLUSIONS Familiarity with the myriad ocular findings of onchocerciasis, and a high-degree of suspicion in subjects residing in endemic areas can help in the correct diagnosis and implementation of appropriate therapy. Onchocercal chorioretinitis is a slow, insidious, progressive, and prolonged polymorphous disease.
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Affiliation(s)
- Ahmad Mansour
- Retina Service, Department of Ophthalmology, American University of Beirut, Beirut 1107, Lebanon
| | - Linnet Rodriguez
- Retina Service, Wills Eye Hospital, Thomas Jefferson Medical Center, Philadelphia, PA 19107, USA; (L.R.); (H.M.)
| | - Hana Mansour
- Retina Service, Wills Eye Hospital, Thomas Jefferson Medical Center, Philadelphia, PA 19107, USA; (L.R.); (H.M.)
| | - Madeleine Yehia
- Retina Service, University of Illinois Chicago, Chicago, IL 60612, USA;
| | - Maurizio Battaglia Parodi
- Retina Service, Department of Ophthalmology, Ospedale San Raffaele, University Vita-Salute, 20132 Milan, Italy;
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Kura K, Milton P, Hamley JID, Walker M, Bakajika DK, Kanza EM, Opoku NO, Howard H, Nigo MM, Asare S, Olipoh G, Attah SK, Mambandu GL, Kennedy KK, Kataliko K, Mumbere M, Halleux CM, Hopkins A, Kuesel AC, Kinrade S, Basáñez MG. Can mass drug administration of moxidectin accelerate onchocerciasis elimination in Africa? Philos Trans R Soc Lond B Biol Sci 2023; 378:20220277. [PMID: 37598705 PMCID: PMC10440165 DOI: 10.1098/rstb.2022.0277] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/11/2023] [Indexed: 08/22/2023] Open
Abstract
Epidemiological and modelling studies suggest that elimination of Onchocerca volvulus transmission (EoT) throughout Africa may not be achievable with annual mass drug administration (MDA) of ivermectin alone, particularly in areas of high endemicity and vector density. Single-dose Phase II and III clinical trials demonstrated moxidectin's superiority over ivermectin for prolonged clearance of O. volvulus microfilariae. We used the stochastic, individual-based EPIONCHO-IBM model to compare the probabilities of reaching EoT between ivermectin and moxidectin MDA for a range of endemicity levels (30 to 70% baseline microfilarial prevalence), treatment frequencies (annual and biannual) and therapeutic coverage/adherence values (65 and 80% of total population, with, respectively, 5 and 1% of systematic non-adherence). EPIONCHO-IBM's projections indicate that biannual (six-monthly) moxidectin MDA can reduce by half the number of years necessary to achieve EoT in mesoendemic areas and might be the only strategy that can achieve EoT in hyperendemic areas. Data needed to improve modelling projections include (i) the effect of repeated annual and biannual moxidectin treatment; (ii) inter- and intra-individual variation in response to successive treatments with moxidectin or ivermectin; (iii) the effect of moxidectin and ivermectin treatment on L3 development into adult worms; and (iv) patterns of adherence to moxidectin and ivermectin MDA. This article is part of the theme issue 'Challenges in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield AL9 7TA, UK
| | - Didier K. Bakajika
- Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN), African Regional Office of the World Health Organization (WHO/AFRO/ESPEN), Brazzaville, Democratic Republic of Congo
| | - Eric M. Kanza
- Programme Nationale de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive (PNLMTN-CTP), Ministère de la Santé Publique, Kinshasa, Democratic Republic of the Congo
| | - Nicholas O. Opoku
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Hayford Howard
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Maurice M. Nigo
- Institut Supérieur des Techniques Médicales de Nyankunde, Bunia, Democratic Republic of the Congo
| | | | - George Olipoh
- Precious Minerals Marketing Company, National Assay Centre, Technical Department, Diamond House, Accra, GA-143-2548, Ghana
| | - Simon K. Attah
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, Accra, Ghana
| | - Germain L. Mambandu
- Inspection Provinciale de la Santé de la Tshopo, Kisangani, Democratic Republic of the Congo
| | - Kambale Kasonia Kennedy
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Kambale Kataliko
- Centre de Santé CECA 20 de Mabakanga, Beni, Nord Kivu, Democratic Republic of the Congo
| | - Mupenzi Mumbere
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Christine M. Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Gravesend, Kent DA11 OSL, UK
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Sally Kinrade
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
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Dorkenoo AM, Phillips AE, Klein L, Lack F, Ataba E, Yakpa K, Tagba AE, Assoti BE, Sossou E, Tchalim M, Datagni G, Seim A, Milord MD, Kassankogno Y. Progress from morbidity control to elimination as a public health problem of schistosomiasis and the status of soil-transmitted helminth infection in Togo: a second impact assessment after ten rounds of mass drug administration. Parasit Vectors 2023; 16:314. [PMID: 37667301 PMCID: PMC10478252 DOI: 10.1186/s13071-023-05882-2] [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: 01/12/2023] [Accepted: 07/14/2023] [Indexed: 09/06/2023] Open
Abstract
BACKGROUND Due to the burden of schistosomiasis (SCH) and soil-transmitted helminths (STH), Togo Ministry of Health launched a program for Preventive Chemotherapy Neglected Tropical Diseases (PC-NTDs) in 2009, initiating integrated mass drug administration (MDA) the following year for the three PC-NTDs: SCH, STH and onchocerciasis. Significant reduction of infection across the country was noted in 2015 during the first impact assessment, following 5 years of high-coverage MDA implemented at the sub-district level for SCH and district level for STH. After another 5 years of effective MDA, a second survey was conducted in 2021 to re-evaluate the situation of SCH and STH. METHODS A cross-section of school-aged children was taken across ten districts of Togo. A total of 302 schools in 92 sub-districts were sampled, with 24 school-aged children per school resulting in 7248 children surveyed. Urine samples were tested by haemastix® for Schistosoma haematobium, with urine filtration for the presence of eggs conducted on haematuria-positive samples. Stool samples were collected in a subset of 34 sub-districts in seven out of the ten surveyed districts, where STH and Schistosoma mansoni endemicity was high during the 2015 impact assessment. Duplicate (two) Kato-Katz analysis was performed for each stool sample. Sociodemographic and school-level water, sanitation and hygiene information was also collected. RESULTS Overall, SCH prevalence was 5.90% (95% CI: 5.4-6.5), with 5.09% (95% CI: 4.64-5.67) for S. haematobium and 2.56% (95% CI: 1.98-3.29) for S. mansoni. STH prevalence was 19.7% (95% CI: 18.2-21.4), with 19.6% (95% CI: 18.1-21.3) hookworm, 0.08% (95% CI: 2.2-5.8) Trichuris trichiura and 0.04% (95% CI: 0.01-0.33) Ascaris lumbricoides. Compared to baseline, a significant reduction in both SCH (22.2% to 5.90%) and STH (29.2% t0 19.7%) prevalence was observed. Children aged 5-9 years were less infected than older peers aged 10-14 years: 4.76% vs. 7.53% (P < 0.01) for SCH and 17.2% vs. 23.0% (P < 0.01) for STH. CONCLUSIONS After 10 years of high coverage integrated MDA, Togo has achieved low prevalence SCH infection through the sub-district MDA implementation with considerable infection heterogeneity within sub-districts. As STH infection has not reached a level where the infections are not a public health problem, the sub-district treatment strategy could also be adopted in addition to improvement of treatment coverage among preschool age children and hygiene and sanitation practices.
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Affiliation(s)
- Ameyo M Dorkenoo
- National Program for the Control of NTDs, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo.
- Department of Biological and Basic Sciences, Faculty of Health Sciences, University of Lomé, Lomé, Togo.
| | | | - Luke Klein
- Family Health International 360, Washington, DC, USA
| | - Fiali Lack
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Essoham Ataba
- Programme National de Lute Contre le Paludisme, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Kossi Yakpa
- Programme National de Lute Contre le Paludisme, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Atna-Edi Tagba
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Bozi-Esso Assoti
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Efoe Sossou
- Centre Hospitalier Universitaire Sylvanus Olympio, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | - Mawèké Tchalim
- National Program for the Control of NTDs, Ministry of Health, Public Hygiene and Universal Health Coverage, Lomé, Togo
| | | | - Anders Seim
- Health and Development International, Fjellstrand, Norway
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Siewe Fodjo JN, Van Cutsem G, Amaral LJ, Colebunders R. Mortality among persons with epilepsy in onchocerciasis-endemic and non-endemic areas of sub-Saharan Africa: A systematic review and meta-analysis. Seizure 2023; 110:253-261. [PMID: 37451075 DOI: 10.1016/j.seizure.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2023] [Revised: 07/03/2023] [Accepted: 07/10/2023] [Indexed: 07/18/2023] Open
Abstract
PURPOSE To document epilepsy-related mortality in sub-Saharan Africa (SSA) and investigate possible associations with onchocerciasis endemicity. METHODS Systematic review with meta-analysis. Searches were performed in PubMed and Google Scholar (search terms: 'epilepsy'; 'mortality/death'; 'sub-Saharan Africa'). Included studies were classified as high-risk or low-risk for onchocerciasis based on documented endemicity data. Pooled mortality rates and annual case fatality rates (CFR) were calculated, and risk factors for mortality among persons with epilepsy (PWE) were investigated using meta-regression analysis. RESULTS The 28 eligible studies reported 30 epilepsy surveys, of which 9 (30.0%) were conducted in onchocerciasis high-risk sites. The pooled epilepsy mortality rate was 20.9 (95% CI: 5.9-74.4) per 100,000 person-years, and the pooled CFR was 36.2 (95% CI: 23.9-54.4) per 1,000 PWE per year, albeit with substantial between-study heterogeneity. Compared to onchocerciasis low-risk sites, high-risk sites had higher pooled mortality (342.9 versus 10.0 per 100,000 PY; p<0.001) and CFR (57.0 versus 26.6 per 1,000 PWE per year; p = 0.001). Mortality of PWE was almost five-fold that of people without epilepsy (mortality risk ratio: 4.9; 95% CI: 3.5-6.8). Studies in onchocerciasis high-risk sites and the study which recruited only PWE with nodding syndrome were associated with higher CFR (p = 0.044 and p = 0.002, respectively). The leading causes of epilepsy-related death were status epilepticus (58.5%), drowning (15.7%), and sudden unexpected death in epilepsy (10.1%). CONCLUSION Epilepsy mortality remains high in SSA. Most reported causes of death among PWE might be averted by improving seizure control. Better epilepsy prevention and care are urgently needed, particularly in onchocerciasis-endemic settings.
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Affiliation(s)
| | - Gilles Van Cutsem
- Global Health Institute, University of Antwerp, Belgium; Translational Neurosciences, University of Luxembourg, Luxembourg; Centre for Infectious Disease Epidemiology and Research, University of Cape Town, South Africa
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Johanns SI, Gantin RG, Wangala B, Komlan K, Halatoko WA, Banla M, Karabou P, Luty AJF, Schulz-Key H, Köhler C, Soboslay PT. Onchocerca volvulus-specific antibody and cellular responses in onchocerciasis patients treated annually with ivermectin for 30 years and exposed to parasite transmission in central Togo. PLoS Negl Trop Dis 2022; 16:e0010340. [PMID: 35503786 PMCID: PMC9064110 DOI: 10.1371/journal.pntd.0010340] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Accepted: 03/20/2022] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Annual mass drug administrations (MDA) of ivermectin will strongly reduce Onchocerca volvulus microfilariae (mf) in the skin and in the onchocerciasis patients' eyes. Ivermectin treatment will also affect the expression of immunity in patients, such that activated immune defenses may help control and contribute to clearance of mf of O. volvulus. Longitudinal surveys are a prerequisite to determining the impact of ivermectin on the status of anti-parasite immunity, notably in risk zones where parasite transmission and active O. volvulus infections persist. METHODOLOGY/PRINCIPAL FINDINGS Onchocerciasis patients were treated annually with ivermectin and their Onchocerca volvulus antigen (OvAg) specific IgG and cellular responses were investigated before and at 30 years post initial ivermectin treatment (30yPT). Repeated annual ivermectin treatments eliminated persisting O. volvulus microfilariae (mf) from the skin of patients and abrogated patent infections. The OvAg-specific IgG1 and IgG4 responses were diminished at 30yPT to the levels observed in endemic controls. Prior to starting ivermectin treatment, OvAg-induced cellular productions of IL-10, IFN-γ, CCL13, CCL17 and CCL18 were low in patients, and at 30yPT, cellular cytokine and chemokine responses increased to the levels observed in endemic controls. In contrast, mitogen(PHA)- induced IL-10, IFN-γ, CCL17 and CCL18 cellular production was diminished. This divergent response profile thus revealed increased parasite antigen-specific but reduced polyclonal cellular responsiveness in patients. The transmission of O. volvulus continued at the patients' location in the Mô river basin in central Togo 2018 and 2019 when 0.58% and 0.45%, respectively, of Simulium damnosum s.l. vector blackflies carried O. volvulus infections. CONCLUSIONS/SIGNIFICANCE Repeated annual ivermectin treatment of onchocerciasis patients durably inhibited their patent O. volvulus infections despite ongoing low-level parasite transmission in the study area. Repeated MDA with ivermectin affects the expression of immunity in patients. O. volvulus parasite-specific antibody levels diminished to levels seen in infection-free endemic controls. With low antibody levels, antibody-dependent cellular cytotoxic responses against tissue-dwelling O. volvulus larvae will weaken. O. volvulus antigen inducible cytokine and chemokine production increased in treated mf-negative patients, while their innate responsiveness to mitogen declined. Such lower innate responsiveness in elderly patients could contribute to reduced adaptive immune responses to parasite infections and vaccines. On the other hand, increased specific cellular chemokine responses in mf-negative onchocerciasis patients could reflect effector cell activation against tissue invasive larval stages of O. volvulus. The annual Simulium damnosum s.l. biting rate observed in the Mô river basin was similar to levels prior to initiation of MDA with ivermectin, and the positive rtPCR results reported here confirm ongoing O. volvulus transmission.
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Affiliation(s)
- Saskia I. Johanns
- University Clinics Tübingen, Institute for Tropical Medicine, Eberhard-Karls University, Tübingen, Germany
| | - Richard G. Gantin
- Onchocerciasis Reference Laboratory, Institut National d’Hygiene, Centre Hospitalier Regional, Sokode, Togo
| | - Bawoubadi Wangala
- Onchocerciasis Reference Laboratory, Institut National d’Hygiene, Centre Hospitalier Regional, Sokode, Togo
| | | | | | - Meba Banla
- Centre Hospitalier Universitaire, Université de Lomé, Lomé, Togo
| | | | - Adrian JF Luty
- Université de Paris, Institut de Recherche pour le Développement, Paris, France
| | - Hartwig Schulz-Key
- University Clinics Tübingen, Institute for Tropical Medicine, Eberhard-Karls University, Tübingen, Germany
| | - Carsten Köhler
- University Clinics Tübingen, Institute for Tropical Medicine, Eberhard-Karls University, Tübingen, Germany
| | - Peter T. Soboslay
- University Clinics Tübingen, Institute for Tropical Medicine, Eberhard-Karls University, Tübingen, Germany
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Anti-Th17 and anti-Th2 responses effects of hydro-ethanolic extracts of Aframomum melegueta, Khaya senegalensis and Xylopia aethiopica in hyperreactive onchocerciasis individuals’ peripheral blood mononuclear cells. PLoS Negl Trop Dis 2022; 16:e0010341. [PMID: 35468134 PMCID: PMC9071127 DOI: 10.1371/journal.pntd.0010341] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Revised: 05/05/2022] [Accepted: 03/18/2022] [Indexed: 12/04/2022] Open
Abstract
Hyperreactive onchocerciasis (HO) is characterized by a severe skin inflammation with elevated Th17-Th2 combined responses. We previously demonstrated the anthelminthic activity of Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS) used by traditional healers to treat helminthiasis in the endemic area of Togo. However, their effect on severe onchocerciasis is poorly investigated. The present study aimed to investigate the anti-Th17 and anti-Th2 effects of hydro-ethanolic extracts of AM, XA and KS during HO. Onchocerca volvulus-infected individuals were recruited in the Central region of Togo in 2018. Isolated peripheral blood mononuclear cells (PBMCs) from both generalized onchocerciasis (GEO) and HO forms were activated with anti-CD3 and anti-CD28 monoclonal antibodies in the presence or absence of the hydro-ethanolic extracts of AM, XA and KS as well as their delipidated, deproteinized and deglycosylated fractions. After 72 hours, cytokines were assayed from cell culture supernatants. Then, flow cytometry was used to investigate the effects of the extracts on cell activation, proliferation, intracellular cytokines and T cells transcription factors. The production of both Th17 and Th2 cytokines IL-17A and IL-5 were significantly inhibited upon T-cell receptor (TCR) activation in the presence of the hydro-ethanolic extracts of AM, XA and KS in HO individuals’ PBMCs in vitro. AM and XA inhibited CD4+RORC2+IL-17A+ and CD4+GATA3+IL-4+ cell populations induction. This inhibition was not Th1 nor Treg-dependent since both IFN-γ and IL-10 were also inhibited by the extracts. AM and XA did not interfere with T cell activation and proliferation for their inhibitory pathways. Lipid and protein compounds from AM and XA were associated with the inhibition of IL-17A. This study showed that in addition to their anthelminthic effects, hydro-ethanolic extracts of Aframomum melegueta, Xylopia aethiopica and Khaya senegalensis could downregulate both Th17 and Th2 responses and prevent the severe skin disorder observed. Severe form of human onchocerciasis also called hyperreactive onchocerciasis (HO) is characterized by skin disorders such as dermatitis. Our previous study showed that concomitant Th2 and Th17 responses play a role in the pathophysiology of the disease. In Onchocerca volvulus endemic areas such as Togo, traditional healers (TH) used to treat this disease with medicinal plants such as Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS). Mass drug administration including ivermectin and albendazole has been used over the past decade to control and eradicate helminths infections. Despite its successes, resistance to ivermectin has been reported and therefore, alternative drugs are urgently needed. We previously confirmed in vitro the anthelminthic effects of Aframomum melegueta (AM), Xylopia aethiopica (XA) and Khaya senegalensis (KS). However, their effect on severe onchocerciasis has not been demonstrated. Here, the anti-Th17 and anti-Th2 effects of hydro-ethanolic extracts of AM, XA and KS during HO were investigated. The data showed that in addition to their helminth-killing effects, plant-derived molecules AM, XA and KS downregulated Th2 and Th17 profiles and therefore, could be candidates for the development of new drugs not only for the treatment of helminth-induced inflammatory pathologies but also auto-immune Th2/Th17-dependent inflammatory diseases in general.
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Evaluating the diagnostic test accuracy of molecular xenomonitoring methods for characterising the community burden of Onchocerciasis. PLoS Negl Trop Dis 2021; 15:e0009812. [PMID: 34637436 PMCID: PMC8509893 DOI: 10.1371/journal.pntd.0009812] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 09/13/2021] [Indexed: 11/19/2022] Open
Abstract
Background Molecular xenomonitoring (MX), the detection of parasite nucleic acid in the vector population, is recommended for onchocerciasis surveillance in elimination settings. However, the sensitivity of MX for detecting onchocerciasis-positive communities has not previously been evaluated. MX may have additional applications for control programmes but its utility is restricted by a limited understanding of the relationship between MX results and human prevalence. Methods We conducted a systematic review of studies reporting the prevalence of Onchocerca volvulus DNA in wild-caught Simulium spp. flies (MX rate) and corresponding prevalence of microfilaria (mf) in humans. We evaluated the sensitivity of MX for detecting onchocerciasis-positive communities and describe the characteristics of studies with reduced sensitivity. We conducted a linear regression to evaluate the relationship between mf prevalence and MX rate. Results We identified 15 relevant studies, with 13 studies comprising 34 study communities included in the quantitative analyses. Most communities were at advanced stages towards elimination and had no or extremely low human prevalence. MX detected positive flies in every study area with >1% mf prevalence, with the exception of one study conducted in the Venezuelan Amazonian focus. We identified a significant relationship between the two measurements, with mf prevalence accounting for half of the variation in MX rate (R2 0.50, p<0.001). Conclusion MX is sensitive to communities with ongoing onchocerciasis transmission. It has potential to predict human mf prevalence, but further data is required to understand this relationship, particularly from MX surveys conducted earlier in control programmes before transmission has been interrupted. Traditional surveillance of onchocerciasis relies on the detection of Onchocerca volvulus microfilaria or antibodies in human skin or blood samples. Molecular xenomonitoring, the detection of parasite nucleic acid in vector insects, provides a non-invasive alternative. The sensitivity of molecular xenomonitoring to areas where infected people are found has not previously been evaluated and the extent to which xenomonitoring can be used to predict human prevalence is unknown. We searched for previous studies that reported the infection rates in humans and detection rates in black flies, finding 15 studies comprising 34 study communities that contributed to our analyses. Studies were conducted across Africa and the Americas, mostly in areas of very low prevalence. The findings show molecular xenomonitoring was sensitive to areas with greater than 1% microfilaria prevalence in the human population, indicating that molecular xenomonitoring is effective at detecting ongoing transmission. We further found evidence that infection rates in humans and detection rates in flies were related, providing scope for the use of xenomonitoring to predict human prevalence. With further research to better understand this relationship, control programmes may be able to use xenomonitoring for other purposes such as identifying areas that require intervention and monitoring the impact of treatments.
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Dusabimana A, Bhwana D, Mandro M, Mmbando BP, Siewe Fodjo JN, Colebunders R. OV16 Seroprevalence among Persons with Epilepsy in Onchocerciasis Endemic Regions: A Multi-Country Study. Pathogens 2020; 9:pathogens9100847. [PMID: 33081184 PMCID: PMC7650690 DOI: 10.3390/pathogens9100847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 11/16/2022] Open
Abstract
There is growing epidemiological evidence that onchocerciasis may induce epilepsy. High prevalence of onchocerciasis has been reported in onchocerciasis-meso and hyper-endemic regions. We aimed to determine the OV16 antibody prevalence in persons with epilepsy (PWE) in four onchocerciasis-endemic regions. PWE were identified during studies in Mahenge area (Tanzania), Kitgum and Pader districts (Uganda), the Mbam and Sanaga river valleys (Cameroon), and the Logo health zone (Democratic Republic of Congo). Exposure to Onchocerca volvulus was assessed by testing PWE for OV16 IgG4 antibodies using a rapid diagnostic test. The OV16 seroprevalence among PWE in the four onchocerciasis-endemic study sites ranged from 35.2% to 59.7%. OV16 seroprevalence increased with age until the age of 39 years, after which it decreased drastically. Our study suggests that, in onchocerciasis-endemic regions, epilepsy in young people is often associated with onchocerciasis, while epilepsy in older persons seems unrelated to O. volvulus exposure.
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Affiliation(s)
- Alfred Dusabimana
- Global Health Institute, Gouverneur Kinsbergen Centrum, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.)
| | - Dan Bhwana
- National Institute for Medical Research, Tanga Centre, P.O. Box 5004, Tanga, Tanzania; (D.B.); (B.P.M.)
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia, P.O. Box 57, Ituri, Congo;
| | - Bruno P. Mmbando
- National Institute for Medical Research, Tanga Centre, P.O. Box 5004, Tanga, Tanzania; (D.B.); (B.P.M.)
| | - Joseph N. Siewe Fodjo
- Global Health Institute, Gouverneur Kinsbergen Centrum, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.)
| | - Robert Colebunders
- Global Health Institute, Gouverneur Kinsbergen Centrum, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (J.N.S.F.)
- Correspondence:
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10
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Gebrezgabiher G, Mekonnen Z, Yewhalaw D, Hailu A. Status of parasitological indicators and morbidity burden of onchocerciasis after years of successive implementation of mass distribution of ivermectin in selected communities of Yeki and Asosa districts, Ethiopia. BMC Public Health 2020; 20:1233. [PMID: 32787813 PMCID: PMC7425055 DOI: 10.1186/s12889-020-09344-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Accepted: 08/04/2020] [Indexed: 11/23/2022] Open
Abstract
Background Control and elimination of onchocerciasis requires regular follow-up and evaluation of community directed treatment with ivermectin (CDTi) program implementation. This research was aimed to assess the epidemiological status of onchocerciasis in disease endemic communities of Asosa and Yeki districts of Ethiopia after 5 and 15 years of successive CDTi respectively, and to evaluate the decline in infection and morbidity burden. Methods A community-based cross-sectional study was conducted from August 2017 to January 2018 (i.e. within 2–7 months since the last treatment) using interview, physical and parasitological examinations. Pre-CDTi epidemiological data were obtained from studies conducted prior to the launch of CDTi. Results A total of 3002 individuals (1567 from Asosa and 1435 from Yeki) were included. No infection was detected from Yeki. In Asosa, the prevalence of infection was 1.6%. The geometric mean intensity of infection was 0.02 mf/mg of skin snip. The prevalence rates of dermatitis, depigmentation, nodule, and atrophy in Yeki were 33(2.3%), 57(4%), 37(2.6%) and 11(0.7%), respectively. The prevalence rates of papular dermatitis, depigmentation, palpable nodule, atrophy, and blindness in Asosa were 94(6%), 38(2.4%), 30(1.9%), 28(1.8%) and 2(0.1%), respectively. Five years of CDTi had significantly reduced prevalence and intensity of infection by 91.8% (p < 0.001) and 99.7% (p < 0.001), respectively. Moreover, CDTi reduced prevalence of papular dermatitis by 95.9% (p < 0.001), palpable nodule by 90.5% (p < 0.001), and atrophy by 30% (p = 0.6) in Yeki. Similarly, CDTi reduced prevalence of papular dermatitis by 88.6% (p < 0.001), depigmentation by 90.3% (p < 0.001), atrophy by 89.5% (p < 0.001), and blindness by 90% (p < 0.001) in Asosa. Conclusions Fifteen years of successive CDTi had brought the infection from high to zero in Yeki. However, thorough entomological and serological data need to be generated to ascertain whether complete interruption of parasite transmission has been attained, and for considerations of an evidence-based CDTi cessation. Five years of CDTi in Asosa has significantly reduced the infection and morbidity of onchocerciasis to very low level. We, hereby, recommend biannual CDTi to continue in Asosa and its surroundings until the infection transmission is fully interrupted.
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Affiliation(s)
- Gebremedhin Gebrezgabiher
- College of Veterinary Medicine, Samara University, P.O. Box 132, Samara, Ethiopia. .,School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia.
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, Jimma, Ethiopia.,Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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11
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Milton P, Hamley JID, Walker M, Basáñez MG. Moxidectin: an oral treatment for human onchocerciasis. Expert Rev Anti Infect Ther 2020; 18:1067-1081. [PMID: 32715787 DOI: 10.1080/14787210.2020.1792772] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
INTRODUCTION Moxidectin is a milbemycin endectocide recently approved for the treatment of human onchocerciasis. Onchocerciasis, earmarked for elimination of transmission, is a filarial infection endemic in Africa, Yemen, and the Amazonian focus straddling Venezuela and Brazil. Concerns over whether the predominant treatment strategy (yearly mass drug administration (MDA) of ivermectin) is sufficient to achieve elimination in all endemic foci have refocussed attention upon alternative treatments. Moxidectin's stronger and longer microfilarial suppression compared to ivermectin in both phase II and III clinical trials indicates its potential as a novel powerful drug for onchocerciasis elimination. AREAS COVERED This work summarizes the chemistry and pharmacology of moxidectin, reviews the phase II and III clinical trials evidence on tolerability, safety, and efficacy of moxidectin versus ivermectin, and discusses the implications of moxidectin's current regulatory status. EXPERT OPINION Moxidectin's superior clinical performance has the potential to substantially reduce times to elimination compared to ivermectin. If donated, moxidectin could mitigate the additional programmatic costs of biannual ivermectin distribution because, unlike other alternatives, it can use the existing community-directed treatment infrastructure. A pediatric indication (for children <12 years) and determination of its usefulness in onchocerciasis-loiasis co-endemic areas will greatly help fulfill the potential of moxidectin for the treatment and elimination of onchocerciasis.
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Affiliation(s)
- Philip Milton
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Jonathan I D Hamley
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK.,London Centre for Neglected Tropical Disease Research, Department of Pathobiology and Population Sciences, Royal Veterinary College , Hatfield, UK
| | - María-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC GIDA), Department of Infectious Disease Epidemiology, Imperial College London , London, UK
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12
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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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Hedtke SM, Kuesel AC, Crawford KE, Graves PM, Boussinesq M, Lau CL, Boakye DA, Grant WN. Genomic Epidemiology in Filarial Nematodes: Transforming the Basis for Elimination Program Decisions. Front Genet 2020; 10:1282. [PMID: 31998356 PMCID: PMC6964045 DOI: 10.3389/fgene.2019.01282] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 11/21/2019] [Indexed: 11/25/2022] Open
Abstract
Onchocerciasis and lymphatic filariasis are targeted for elimination, primarily using mass drug administration at the country and community levels. Elimination of transmission is the onchocerciasis target and global elimination as a public health problem is the end point for lymphatic filariasis. Where program duration, treatment coverage, and compliance are sufficiently high, elimination is achievable for both parasites within defined geographic areas. However, transmission has re-emerged after apparent elimination in some areas, and in others has continued despite years of mass drug treatment. A critical question is whether this re-emergence and/or persistence of transmission is due to persistence of local parasites-i.e., the result of insufficient duration or drug coverage, poor parasite response to the drugs, or inadequate methods of assessment and/or criteria for determining when to stop treatment-or due to re-introduction of parasites via human or vector movement from another endemic area. We review recent genetics-based research exploring these questions in Onchocerca volvulus, the filarial nematode that causes onchocerciasis, and Wuchereria bancrofti, the major pathogen for lymphatic filariasis. We focus in particular on the combination of genomic epidemiology and genome-wide associations to delineate transmission zones and distinguish between local and introduced parasites as the source of resurgence or continuing transmission, and to identify genetic markers associated with parasite response to chemotherapy. Our ultimate goal is to assist elimination efforts by developing easy-to-use tools that incorporate genetic information about transmission and drug response for more effective mass drug distribution, surveillance strategies, and decisions on when to stop interventions to improve sustainability of elimination.
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Affiliation(s)
- Shannon M. Hedtke
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Annette C. Kuesel
- Unicef/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, Geneva, Switzerland
| | - Katie E. Crawford
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
| | - Patricia M. Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, QLD, Australia
| | - Michel Boussinesq
- Unité Mixte Internationale 233 "TransVIHMI", Institut de Recherche pour le Développement (IRD), INSERM U1175, University of Montpellier, Montpellier, France
| | - Colleen L. Lau
- Department of Global Health, Research School of Population Health, Australian National University, Acton, ACT, Australia
| | - Daniel A. Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Warwick N. Grant
- Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, VIC, Australia
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14
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Gebrezgabiher G, Mekonnen Z, Yewhalaw D, Hailu A. Reaching the last mile: main challenges relating to and recommendations to accelerate onchocerciasis elimination in Africa. Infect Dis Poverty 2019; 8:60. [PMID: 31269966 PMCID: PMC6609392 DOI: 10.1186/s40249-019-0567-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 06/10/2019] [Indexed: 01/04/2023] Open
Abstract
BACKGROUND Onchocerciasis (river blindness), caused by the filarial worm species Onchocerca volvulus, is a serious vector-borne neglected tropical disease (NTD) of public health and socioeconomic concern. It is transmitted through the bite of black flies of the genus Simulium, and manifested in dermal and ocular lesions. Ninety-nine percent of the total global risk and burden of onchocerciasis is in Africa. This scoping review examines the key challenges related to the elimination of onchocerciasis by 2020-2025 in Africa, and proposes recommendations to overcome the challenges and accelerate disease elimination. To find relevant articles published in peer-reviewed journals, a search of PubMed and Google Scholar databases was carried out. MAIN TEXT Rigorous regional interventions carried out to control and eliminate onchocerciasis in the past four decades in Africa have been effective in bringing the disease burden under control; it is currently not a public health problem in most endemic areas. Notably, transmission of the parasite is interrupted in some hyperendemic localities. Recently, there has been a policy shift from control to complete disease elimination by 2020 in selected countries and by 2025 in the majority of endemic African countries. The WHO has published guidelines for stopping mass drug administration (MDA) and verifying the interruption of transmission and elimination of human onchocerciasis. Therefore, countries have revised their plans, established a goal of disease elimination in line with an evidence based decision to stop MDA and verify elimination, and incorporated it into their NTDs national master plans. Nevertheless, challenges remain pertaining to the elimination of onchocerciasis in Africa. The challenge we review in this paper are: incomplete elimination mapping of all transmission zones, co-endemicity of onchocerciasis and loiasis, possible emergence of ivermectin resistance, uncoordinated cross-border elimination efforts, conflict and civil unrest, suboptimal program implementation, and technical and financial challenges. This paper also proposes recommendations to overcome the challenges and accelerate disease elimination. These are: a need for complete disease elimination mapping, a need for collaborative elimination activities between national programs, a need for a different drug distribution approach in conflict-affected areas, a need for routine monitoring and evaluation of MDA programs, a need for implementing alternative treatment strategies (ATSs) in areas with elimination anticipated beyond 2025, and a need for strong partnerships and continued funding. CONCLUSIONS National programs need to regularly monitor and evaluate the performance and progress of their interventions, while envisaging the complete elimination of onchocerciasis from their territory. Factors hindering the targeted goal of interruption of parasite transmission need to be identified and remedial actions should be taken. If possible and appropriate, ATSs need to be implemented to accelerate disease elimination by 2025.
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Affiliation(s)
- Gebremedhin Gebrezgabiher
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- College of Veterinary Medicine, Samara University, Samara, Ethiopia
| | - Zeleke Mekonnen
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
- Tropical and Infectious Diseases Research Center, Jimma University, Jimma, Ethiopia
| | - Asrat Hailu
- Department of Microbiology, Immunology, and Parasitology, School of Medicine, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia
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15
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Wangala B, Gantin RG, Voßberg PS, Vovor A, Poutouli WP, Komlan K, Banla M, Köhler C, Soboslay PT. Inflammatory and regulatory CCL and CXCL chemokine and cytokine cellular responses in patients with patent Mansonella perstans filariasis. Clin Exp Immunol 2019; 196:111-122. [PMID: 30561772 DOI: 10.1111/cei.13251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2018] [Indexed: 12/17/2022] Open
Abstract
Mansonella perstans (Mp) filariasis is present in large populations in sub-Saharan Africa, and to what extent patent Mp infection modulates the expression of immunity in patients, notably their cellular cytokine and chemokine response profile, remains not well known. We studied the spontaneous and inducible cellular production of chemokines (C-X-C motif) ligand 9 (CXCL9) [monokine induced by interferon (IFN)-γ (MIG)], CXCL-10 [inducible protein (IP)-10], chemokine (C-C motif) ligand 24 (CCL24) (eotaxin-2), CCL22 [macrophage-derived chemokine (MDC)], CCL13 [monocyte chemotactic protein-4 (MCP-4)], CCL18 [pulmonary and activation-regulated chemokine (PARC)], CCL17 [thymus- and activation-regulated chemokine (TARC)] and interleukin (IL)-27 in mansonelliasis patients (Mp-PAT) and mansonelliasis-free controls (CTRL). Freshly isolated peripheral mononuclear blood cells (PBMC) were stimulated with helminth, protozoan and bacterial antigens and mitogen [phytohaemagglutinin (PHA)]. PBMC from Mp-PAT produced spontaneously (without antigen stimulation) significantly higher levels of eotaxin-2, IL-27, IL-8, MCP-4 and MDC than cells from CTRL, while IFN-γ-IP-10 was lower in Mp-PAT. Helminth antigens activated IL-27 and MCP-4 only in CTRL, while Ascaris antigen, Onchocerca antigen, Schistosoma antigen, Entamoeba antigen, Streptococcus antigen, Mycobacteria antigen and PHA stimulated MIG release in CTRL and Mp-PAT. Notably, Entamoeba antigen and PHA strongly depressed (P < 0·0001) eotaxin-2 (CCL24) production in both study groups. Multiple regression analyses disclosed in Mp-PAT and CTRL dissimilar cellular chemokine and cytokine production levels being higher in Mp-PAT for CCL24, IL-27, IL-8, MCP-4, MDC and PARC (for all P < 0·0001), at baseline (P < 0·0001), in response to Entamoeba histolytica strain HM1 antigen (EhAg) (P < 0·0001), Onchocerca volvulus adult worm-derived antigen (OvAg) (P = 0·005), PHA (P < 0·0001) and purified protein derivative (PPD) (P < 0·0001) stimulation. In Mp-PAT with hookworm co-infection, the cellular chemokine production of CXCL10 (IP-10) was diminished. In summary, the chemokine and cytokine responses in Mp-PAT were in general not depressed, PBMC from Mp-PAT produced spontaneously and selectively inducible inflammatory and regulatory chemokines and cytokines at higher levels than CTRL and such diverse and distinctive reactivity supports that patent M. perstans infection will not polarize innate and adaptive cellular immune responsiveness in patients.
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Affiliation(s)
- B Wangala
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo
| | - R G Gantin
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - P S Voßberg
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - A Vovor
- Centre Hospitalier Universitaire Sylvanus Olympio, Laboratory for Hematology, Université de Lomé, Togo
| | - W P Poutouli
- Faculté de Sciences, Université de Lomé, Lomé, Togo
| | - K Komlan
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo
| | - M Banla
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Centre Hospitalier Universitaire Campus, Université de Lomé, Togo
| | - C Köhler
- Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
| | - P T Soboslay
- National Institute of Hygiene, Onchocerciasis Reference Laboratory, Sokodé, Togo.,Institute for Tropical Medicine, University Clinics of Tübingen, Tübingen, Germany
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Mansonella perstans, Onchocerca volvulus and Strongyloides stercoralis infections in rural populations in central and southern Togo. Parasite Epidemiol Control 2018; 3:77-87. [PMID: 29774301 PMCID: PMC5952658 DOI: 10.1016/j.parepi.2018.03.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/12/2018] [Accepted: 03/12/2018] [Indexed: 11/22/2022] Open
Abstract
Background Mansonella perstans, Onchocerca volvulus and Strongyloides stercoralis are widespread helminth parasites in the tropics. Their distribution remains difficult to determine as it may change during national disease control programs and with regional mass drug administration (MDA). Epidemiological surveys are of importance to evaluate the geographical distribution of these helminth parasites and the diseases they may cause, however, up to date epidemiological evaluations on M. perstans and S. stercoralis in Togo are rare, and surveys on O. volvulus are important especially under the aspect of MDA of ivermectin which is performed since decades. Methods Dry blood samples (n = 924) were collected from rural populations in the Régions Central and Plateaux in Togo, and analyzed by parasite-specific real-time PCR and ELISA techniques. Results Dry blood samples from 733 persons where investigated by real-time PCR tested for DNA of blood-circulating M. perstans microfilaria, and a prevalence of 14.9% was detected. Distinct differences were observed between genders, positivity was higher in men increasing with age, and prevalence was highest in the Région Plateaux in Togo. IgG4 responses to O. volvulus antigen (OvAg) were studied in 924 persons and 59% were found positive. The distribution of parasite infestation between age and gender groups was higher in men increasing with age, and regional differences were detected being highest in the Région Plateaux. The diagnostic approach disclosed 64,5% positive IgG4 responses to S. stercoralis infective third-stage larvae-specific antigen (SsL3Ag) in the surveyed regions. Antigen cross reactivity of SsL3Ag with parasite co-infections may limit the calculated prevalence. Singly IgG4 positive for SsL3Ag were 13.9%, doubly positive for OvAg and SsL3Ag were 35.5% and triply positive for M. perstans, O. volvulus and S. stercoralis were 9.9%. Conclusions Mansonelliasis, onchocerciasis and strongyloidiasis remain prevalent in the surveyed regions, yet with local differences. Our observations suggest that transmission of M. perstans, O. volvulus and S. stercoralis may be ongoing. The degree of positive test results in the examined rural communities advocate for the continuation of MDA with ivermectin and albendazole, and further investigations should address the intensity of transmission of these parasites.
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