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Shrestha H, McCulloch K, Chisholm RH, Armoo SK, Veriegh F, Sirwani N, Crawford KE, Osei-Atweneboana MY, Grant WN, Hedtke SM. Synthesizing environmental, epidemiological and vector and parasite genetic data to assist decision making for disease elimination. Mol Ecol 2024; 33:e17357. [PMID: 38683054 DOI: 10.1111/mec.17357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 02/27/2024] [Accepted: 04/05/2024] [Indexed: 05/01/2024]
Abstract
We present a framework for identifying when conditions are favourable for transmission of vector-borne diseases between communities by incorporating predicted disease prevalence mapping with landscape analysis of sociological, environmental and host/parasite genetic data. We explored the relationship between environmental features and gene flow of a filarial parasite of humans, Onchocerca volvulus, and its vector, blackflies in the genus Simulium. We generated a baseline microfilarial prevalence map from point estimates from 47 locations in the ecological transition separating the savannah and forest in Ghana, where transmission of O. volvulus persists despite onchocerciasis control efforts. We generated movement suitability maps based on environmental correlates with mitochondrial population structure of 164 parasites from 15 communities and 93 vectors from only four sampling sites, and compared these to the baseline prevalence map. Parasite genetic distance between sampling locations was significantly associated with elevation (r = .793, p = .005) and soil moisture (r = .507, p = .002), while vector genetic distance was associated with soil moisture (r = .788, p = .0417) and precipitation (r = .835, p = .0417). The correlation between baseline prevalence and parasite resistance surface maps was stronger than that between prevalence and vector resistance surface maps. The centre of the study area had high prevalence and suitability for parasite and vector gene flow, potentially contributing to persistent transmission and suggesting the importance of re-evaluating transmission zone boundaries. With suitably dense sampling, this framework can help delineate transmission zones for onchocerciasis and would be translatable to other vector-borne diseases.
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Affiliation(s)
- Himal Shrestha
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Karen McCulloch
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Rebecca H Chisholm
- Department of Mathematical and Physical Sciences, La Trobe University, Bundoora, Victoria, Australia
- Melbourne School of Population and Global Health, The University of Melbourne, Melbourne, Victoria, Australia
| | - Samuel K Armoo
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Accra, Ghana
| | - Francis Veriegh
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Accra, Ghana
| | - Neha Sirwani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Katie E Crawford
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | | | - Warwick N Grant
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Shannon M Hedtke
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
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Wong MTJ, Anuar NS, Noordin R, Tye GJ. Generation of IgG antibodies against Strongyloides stercoralis in mice via immunization with recombinant antigens A133 and Ss-IR. Acta Trop 2024; 251:107122. [PMID: 38246399 DOI: 10.1016/j.actatropica.2024.107122] [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: 07/24/2023] [Revised: 11/16/2023] [Accepted: 01/13/2024] [Indexed: 01/23/2024]
Abstract
Strongyloidiasis, caused by the nematode Strongyloides stercoralis, remains a threat to global public health, and a vaccine would be useful to control the disease, especially in developing countries. This study aimed to evaluate the efficacy of recombinant proteins, A133 and Ss-IR, as potential vaccine candidates against strongyloidiasis by investigating the humoral and cellular immune responses in immunized mice. Respective antigens were adjuvanted with Complete Freund's Adjuvant (prime) and Incomplete Freund's Adjuvant (boost) and administered intraperitoneally (prime) and subcutaneously (boost) to female BALB/c mice. For antigen-only doses, only antigens were injected without adjuvants. Altogether, 1 prime dose, 4 booster doses, and 2 antigen-only doses were administered successively. ELISAs were conducted to assess the antibody responses, along with flow cytometry and cytokine ELISA to elucidate the cellular immune responses. Results showed that A133 and Ss-IR induced the production of IgG1 and IgG2a, with A133 generating more robust IgG2a responses than Ss-IR. Flow cytometry findings indicated that effector CD8+T-cells and memory B-cells activity were upregulated significantly for A133 only, whereas cytokine ELISA demonstrated that a Th1/Th2/Th17 mixed cell responses were triggered upon vaccination with either antigen. This preliminary study illustrated the good potential of recombinant A133 and Ss-IR as vaccine candidates against S. stercoralis. It provided information on the probable immune mechanism involved in host defence and the elicitation of protection against S. stercoralis.
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Affiliation(s)
- Matthew Tze Jian Wong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Nor Suhada Anuar
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia
| | - Rahmah Noordin
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia; Department of Parasitology and Medical Entomology, Faculty of Medicine, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
| | - Gee Jun Tye
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Pulau Pinang, Malaysia.
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Crawford KE, Hedtke SM, Doyle SR, Kuesel AC, Armoo S, Osei-Atweneboana MY, Grant WN. Genome-based tools for onchocerciasis elimination: utility of the mitochondrial genome for delineating Onchocerca volvulus transmission zones. Int J Parasitol 2024; 54:171-183. [PMID: 37993016 DOI: 10.1016/j.ijpara.2023.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 09/21/2023] [Accepted: 11/13/2023] [Indexed: 11/24/2023]
Abstract
National programs in Africa have expanded their objectives from control of onchocerciasis (river blindness) as a public health problem to elimination of parasite transmission, motivated by the reduction of Onchocerca volvulus infection prevalence in many African meso- and hyperendemic areas due to mass drug administration of ivermectin (MDAi). Given the large, contiguous hypo-, meso-, and hyperendemic areas, sustainable elimination of onchocerciasis in sub-Saharan Africa requires delineation of geographic boundaries for parasite transmission zones, so that programs can consider the risk of parasite re-introduction through vector or human migration from areas with ongoing transmission when making decisions to stop MDAi. We propose that transmission zone boundaries can be delineated by characterising the parasite genetic population structure within and between potential zones. We analysed whole mitochondrial genome sequences of 189 O. volvulus adults to determine the pattern of genetic similarity across three West African countries: Ghana, Mali, and Côte d'Ivoire. Population genetic structure indicates that parasites from villages near the Pru, Daka, and Black Volta rivers in central Ghana belong to one parasite population, indicating that the assumption that river basins constitute individual transmission zones is not supported by the data. Parasites from Mali and Côte d'Ivoire are genetically distinct from those from Ghana. This research provides the basis for developing tools for elimination programs to delineate transmission zones, to estimate the risk of parasite re-introduction via vector or human movement when intervention is stopped in one area while transmission is ongoing in others, to identify the origin of infections detected post-treatment cessation, and to investigate whether persisting prevalence despite ongoing interventions in one area is due to parasites imported from others.
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Affiliation(s)
- Katie E Crawford
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Shannon M Hedtke
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Environment and Genetics, La Trobe University, Bundoora, Victoria, Australia.
| | - Stephen R Doyle
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, 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
| | - Samuel Armoo
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Council for Scientific and Industrial Research, Council Close, Accra, Ghana
| | - Mike Y Osei-Atweneboana
- Biomedical and Public Health Research Unit, CSIR-Water Research Institute, Council for Scientific and Industrial Research, Council Close, Accra, Ghana
| | - Warwick N Grant
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Environment and Genetics, La Trobe University, Bundoora, Victoria, Australia
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Gandasegui J, Power RI, Curry E, Lau DCW, O'Neill CM, Wolstenholme A, Prichard R, Šlapeta J, Doyle SR. Genome structure and population genomics of the canine heartworm Dirofilaria immitis. Int J Parasitol 2024; 54:89-98. [PMID: 37652224 DOI: 10.1016/j.ijpara.2023.07.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 07/24/2023] [Accepted: 07/28/2023] [Indexed: 09/02/2023]
Abstract
The heartworm, Dirofilaria immitis, is a filarial parasitic nematode responsible for significant morbidity and mortality in wild and domesticated canids. Resistance to macrocyclic lactone drug prevention represents a significant threat to parasite control and has prompted investigations to understand the genetic determinants of resistance. This study aimed to improve the genomic resources of D. immitis to enable a more precise understanding of how genetic variation is distributed within and between parasite populations worldwide, which will inform the likelihood and rate by which parasites, and in turn, resistant alleles, might spread. We have guided the scaffolding of a recently published genome assembly for D. immitis (ICBAS_JMDir_1.0) using the chromosomal-scale reference genomes of Brugia malayi and Onchocerca volvulus, resulting in an 89.5 Mb assembly composed of four autosomal- and one sex-linked chromosomal-scale scaffolds representing 99.7% of the genome. Publicly available and new whole-genome sequencing data from 32 D. immitis samples from Australia, Italy and the USA were assessed using principal component analysis, nucleotide diversity (Pi) and absolute genetic divergence (Dxy) to characterise the global genetic structure and measure within- and between-population diversity. These population genetic analyses revealed broad-scale genetic structure among globally diverse samples and differences in genetic diversity between populations; however, fine-scale subpopulation analysis was limited and biased by differences between sample types. Finally, we mapped single nucleotide polymorphisms previously associated with macrocyclic lactone resistance in the new genome assembly, revealing the physical linkage of high-priority variants on chromosome 3, and determined their frequency in the studied populations. This new chromosomal assembly for D. immitis now allows for a more precise investigation of selection on genome-wide genetic variation and will enhance our understanding of parasite transmission and the spread of genetic variants responsible for resistance to treatment.
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Affiliation(s)
- Javier Gandasegui
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - University of Barcelona, Barcelona, Spain.
| | - Rosemonde I Power
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Emily Curry
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, Canada.
| | - Daisy Ching-Wai Lau
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Connor M O'Neill
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Adrian Wolstenholme
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Roger Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, Canada.
| | - Jan Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, NSW, Australia.
| | - Stephen R Doyle
- Wellcome Sanger Institute, Cambridgeshire CB10 1SA, United Kingdom.
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Otabil KB, Basáñez MG, Ankrah B, Opoku SA, Kyei DO, Hagan R, Ababio R, Bart-Plange EJ, Babae TN, Kudzordzi PC, Darko VA, Bamfo JG, Ameyaw J, Raji AS, Hadermann A, Schallig HDFH, Colebunders R. Persistence of onchocerciasis and associated dermatologic and ophthalmic pathologies after 27 years of ivermectin mass drug administration in the middle belt of Ghana. Trop Med Int Health 2023; 28:844-854. [PMID: 37846505 DOI: 10.1111/tmi.13937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2023]
Abstract
OBJECTIVES There is a pressing need to regularly evaluate the progress of onchocerciasis elimination programmes to timely identify and mitigate potential risks hindering the reaching of the 2030 targets proposed by the World Health Organization (WHO) in its roadmap on neglected tropical diseases (NTDs). We determined the prevalence of onchocerciasis and associated dermatological and ophthalmological manifestations in six endemic communities in the Bono Region of Ghana after 27 years of ivermectin mass treatment. METHODS In a cross-sectional study, 564 participants aged ≥5 years were enrolled (49.1% females), with a median age of 26 (range: 5-89) years. In 54% and 47%, skin-snip microscopy and Ov16 rapid diagnostic tests were performed, respectively. Skin disease was determined using the WHO Skin NTD App. Visual function assessments included tests of visual acuity. RESULTS The overall microfilarial prevalence was 12.5% (38/305) and Ov16 seroprevalence was 24.2% (64/265). Severe itching was recorded in 24.3%, acute papular onchodermatitis in 52.8%, chronic papular onchodermatitis in 12.5%, lichenified onchodermatitis in 0.7%, skin atrophy in 11.3%, depigmentation in 1.7% and palpable nodules in 5.3%. Of the 301 persons in which visual acuity was examined, 17% were visually impaired and 5.3% were blind and 47.3% presented with cataract. Chronic papular onchodermatitis, lichenified onchodermatitis, depigmentation and visual impairment were significantly associated with the presence of skin microfilariae and Ov16 seropositivity. CONCLUSIONS The persistence of Onchocerca volvulus infection and onchocerciasis-associated dermatological and ophthalmological pathologies after prolonged treatment is of concern. There is a need to include morbidity management in onchocerciasis elimination programmes and understand better patterns of treatment coverage, adherence and actual intake of ivermectin.
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Affiliation(s)
- Kenneth Bentum Otabil
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - María-Gloria Basáñez
- Department of Infectious Disease Epidemiology, MRC Centre for Global Infectious Disease Analysis (MRC GIDA), and London Centre for Neglected Tropical Disease Research, School of Public Health, Imperial College London, London, UK
| | - Blessing Ankrah
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Stephen Agyemang Opoku
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Dennis Ofori Kyei
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Rhoda Hagan
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Richmond Ababio
- Department of Medical Laboratory Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Emmanuel John Bart-Plange
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Theophilus Nti Babae
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Prince-Charles Kudzordzi
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Vera Achiaa Darko
- Consortium for Neglected Tropical Diseases and One Health, Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
- STU Clinic, Sunyani Technical University, Sunyani, Bono Region, Ghana
| | | | | | - Abdul Sakibu Raji
- Department of Biological Science, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana
| | - Amber Hadermann
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
| | - Henk D F H Schallig
- Department of Medical Microbiology, Experimental Parasitology Unit, Amsterdam University Medical Centres, Academic Medical Centre at the University of Amsterdam, Amsterdam, The Netherlands
| | - Robert Colebunders
- Global Health Institute, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
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Kura K, Milton P, Hamley JID, Walker M, Bakajika DK, Kanza EM, Opoku NO, Howard H, Nigo MM, Asare S, Olipoh G, Attah SK, Mambandu GL, Kennedy KK, Kataliko K, Mumbere M, Halleux CM, Hopkins A, Kuesel AC, Kinrade S, Basáñez MG. Can mass drug administration of moxidectin accelerate onchocerciasis elimination in Africa? Philos Trans R Soc Lond B Biol Sci 2023; 378:20220277. [PMID: 37598705 PMCID: PMC10440165 DOI: 10.1098/rstb.2022.0277] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 04/11/2023] [Indexed: 08/22/2023] Open
Abstract
Epidemiological and modelling studies suggest that elimination of Onchocerca volvulus transmission (EoT) throughout Africa may not be achievable with annual mass drug administration (MDA) of ivermectin alone, particularly in areas of high endemicity and vector density. Single-dose Phase II and III clinical trials demonstrated moxidectin's superiority over ivermectin for prolonged clearance of O. volvulus microfilariae. We used the stochastic, individual-based EPIONCHO-IBM model to compare the probabilities of reaching EoT between ivermectin and moxidectin MDA for a range of endemicity levels (30 to 70% baseline microfilarial prevalence), treatment frequencies (annual and biannual) and therapeutic coverage/adherence values (65 and 80% of total population, with, respectively, 5 and 1% of systematic non-adherence). EPIONCHO-IBM's projections indicate that biannual (six-monthly) moxidectin MDA can reduce by half the number of years necessary to achieve EoT in mesoendemic areas and might be the only strategy that can achieve EoT in hyperendemic areas. Data needed to improve modelling projections include (i) the effect of repeated annual and biannual moxidectin treatment; (ii) inter- and intra-individual variation in response to successive treatments with moxidectin or ivermectin; (iii) the effect of moxidectin and ivermectin treatment on L3 development into adult worms; and (iv) patterns of adherence to moxidectin and ivermectin MDA. This article is part of the theme issue 'Challenges in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.
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Affiliation(s)
- Klodeta Kura
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield AL9 7TA, UK
| | - Didier K. Bakajika
- Expanded Special Project for Elimination of Neglected Tropical Diseases (ESPEN), African Regional Office of the World Health Organization (WHO/AFRO/ESPEN), Brazzaville, Democratic Republic of Congo
| | - Eric M. Kanza
- Programme Nationale de Lutte contre les Maladies Tropicales Négligées à Chimiothérapie Préventive (PNLMTN-CTP), Ministère de la Santé Publique, Kinshasa, Democratic Republic of the Congo
| | - Nicholas O. Opoku
- Department of Epidemiology and Biostatistics, School of Public Health, University of Health and Allied Sciences, Hohoe, Ghana
| | - Hayford Howard
- Liberia Institute for Biomedical Research (LIBR), Monrovia, Liberia
| | - Maurice M. Nigo
- Institut Supérieur des Techniques Médicales de Nyankunde, Bunia, Democratic Republic of the Congo
| | | | - George Olipoh
- Precious Minerals Marketing Company, National Assay Centre, Technical Department, Diamond House, Accra, GA-143-2548, Ghana
| | - Simon K. Attah
- Department of Medical Microbiology, University of Ghana Medical School, College of Health Sciences, Accra, Ghana
| | - Germain L. Mambandu
- Inspection Provinciale de la Santé de la Tshopo, Kisangani, Democratic Republic of the Congo
| | - Kambale Kasonia Kennedy
- Department of Clinical Research, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Kambale Kataliko
- Centre de Santé CECA 20 de Mabakanga, Beni, Nord Kivu, Democratic Republic of the Congo
| | - Mupenzi Mumbere
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Christine M. Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Gravesend, Kent DA11 OSL, UK
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1211 Geneva 27, Switzerland
| | - Sally Kinrade
- Medicines Development for Global Health, 18 Kavanagh Street, Southbank, Victoria 3006, Australia
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, UK
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Hedtke SM, Kode A, Ukety TO, Mande JL, Abhafule GM, Raciu AA, Uvon CB, Jada SR, Hotterbeekx A, Siewe Fodjo JN, Mitreva M, Sebit W, Colebunders R, Grant WN, Kuesel AC. Procedure for Handling and Storage of Onchocerca volvulus Microfilariae Obtained from Skin Snips for Downstream Genetic Work. Trop Med Infect Dis 2023; 8:445. [PMID: 37755906 PMCID: PMC10536066 DOI: 10.3390/tropicalmed8090445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Revised: 09/04/2023] [Accepted: 09/07/2023] [Indexed: 09/28/2023] Open
Abstract
WHO and endemic countries target elimination of transmission of Onchocerca volvulus, the parasite causing onchocerciasis. Population genetic analysis of O. volvulus may provide data to improve the evidence base for decisions on when, where, and for how long to deploy which interventions and post-intervention surveillance to achieve elimination. Development of necessary methods and tools requires parasites suitable for genetic analysis. Based on our experience with microfilariae obtained from different collaborators, we developed a microfilariae transfer procedure for large-scale studies in the Democratic Republic of Congo (DRC) comparing safety and efficacy of ivermectin, the mainstay of current onchocerciasis elimination strategies, and moxidectin, a new drug. This procedure is designed to increase the percentage of microfilariae in skin snips suitable for genetic analysis, improve assignment to metadata, and minimize time and materials needed by the researchers collecting the microfilariae. Among 664 microfilariae from South Sudan, 35.7% and 39.5% failed the mitochondrial and nuclear qPCR assay. Among the 576 microfilariae from DRC, 16.0% and 16.7% failed these assays, respectively. This difference may not only be related to the microfilariae transfer procedure but also to other factors, notably the ethanol concentration in the tubes in which microfilariae were stored (64% vs. ≥75%).
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Affiliation(s)
- Shannon M Hedtke
- Department of Environment and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
| | - Anusha Kode
- Department of Environment and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
| | - Tony O Ukety
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Democratic Republic of the Congo
| | - Jöel L Mande
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Democratic Republic of the Congo
| | - Germain M Abhafule
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Democratic Republic of the Congo
| | - Anuarite A Raciu
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Democratic Republic of the Congo
| | - Claude B Uvon
- Centre de Recherche en Maladies Tropicales (CRMT), Bunia P.O. Box 143, Democratic Republic of the Congo
| | | | - An Hotterbeekx
- Global Health Institute, University of Antwerp, 2610 Antwerp, Belgium
| | | | - Makedonka Mitreva
- Department of Medicine, Washington University in St. Louis and McDonnell Genome Institute, St. Louis, MO 63108, USA
| | - Wilson Sebit
- National Public Health Laboratory, Juba P.O. Box 88, South Sudan
| | | | - Warwick N Grant
- Department of Environment and Genetics, La Trobe University, Bundoora, VIC 3086, Australia
| | - Annette C Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, CH-1211 Geneva, Switzerland
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8
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Hedtke SM, Choi YJ, Kode A, Chalasani GC, Sirwani N, Jada SR, Hotterbeekx A, Mandro M, Siewe Fodjo JN, Amambo GN, Abong RA, Wanji S, Kuesel AC, Colebunders R, Mitreva M, Grant WN. Assessing Onchocerca volvulus Intensity of Infection and Genetic Diversity Using Mitochondrial Genome Sequencing of Single Microfilariae Obtained before and after Ivermectin Treatment. Pathogens 2023; 12:971. [PMID: 37513818 PMCID: PMC10385737 DOI: 10.3390/pathogens12070971] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 07/16/2023] [Accepted: 07/17/2023] [Indexed: 07/30/2023] Open
Abstract
Onchocerciasis is a neglected tropical disease targeted for elimination using ivermectin mass administration. Ivermectin kills the microfilariae and temporarily arrests microfilariae production by the macrofilariae. We genotyped 436 microfilariae from 10 people each in Ituri, Democratic Republic of the Congo (DRC), and Maridi County, South Sudan, collected before and 4-5 months after ivermectin treatment. Population genetic analyses identified 52 and 103 mitochondrial DNA haplotypes among the microfilariae from DRC and South Sudan, respectively, with few haplotypes shared between people. The percentage of genotype-based correct assignment to person within DRC was ~88% and within South Sudan ~64%. Rarefaction and extrapolation analysis showed that the genetic diversity in DRC, and even more so in South Sudan, was captured incompletely. The results indicate that the per-person adult worm burden is likely higher in South Sudan than DRC. Analyses of haplotype data from a subsample (n = 4) did not discriminate genetically between pre- and post-treatment microfilariae, confirming that post-treatment microfilariae are not the result of new infections. With appropriate sampling, mitochondrial haplotype analysis could help monitor changes in the number of macrofilariae in a population as a result of treatment, identify cases of potential treatment failure, and detect new infections as an indicator of continuing transmission.
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Affiliation(s)
- Shannon M. Hedtke
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Young-Jun Choi
- Department of Medicine, Washington University in St. Louis and McDonnell Genome Institute, St. Louis, MO 63108, USA; (Y.-J.C.); (M.M.)
| | - Anusha Kode
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Gowtam C. Chalasani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | - Neha Sirwani
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
| | | | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia P.O. Box 57, Democratic Republic of the Congo;
| | - Joseph N. Siewe Fodjo
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Glory Ngongeh Amambo
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
| | - Raphael A. Abong
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
- Research Foundation for Tropical Diseases and Environment (REFOTDE), Buea P.O. Box 474, Cameroon
| | - Samuel Wanji
- Parasites and Vectors Research Unit, Department of Microbiology and Parasitology, Faculty of Science, University of Buea, Buea P.O. Box 63, Cameroon; (G.N.A.); (R.A.A.); (S.W.)
- Research Foundation for Tropical Diseases and Environment (REFOTDE), Buea P.O. Box 474, Cameroon
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organization, 1202 Geneva, Switzerland;
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.H.); (J.N.S.F.); (R.C.)
| | - Makedonka Mitreva
- Department of Medicine, Washington University in St. Louis and McDonnell Genome Institute, St. Louis, MO 63108, USA; (Y.-J.C.); (M.M.)
| | - Warwick N. Grant
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, VIC 3086, Australia; (A.K.); (G.C.C.); (N.S.); (W.N.G.)
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9
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Shaver AO, Wit J, Dilks CM, Crombie TA, Li H, Aroian RV, Andersen EC. Variation in anthelmintic responses are driven by genetic differences among diverse C. elegans wild strains. PLoS Pathog 2023; 19:e1011285. [PMID: 37011090 PMCID: PMC10101645 DOI: 10.1371/journal.ppat.1011285] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 04/13/2023] [Accepted: 03/08/2023] [Indexed: 04/05/2023] Open
Abstract
Treatment of parasitic nematode infections in humans and livestock relies on a limited arsenal of anthelmintic drugs that have historically reduced parasite burdens. However, anthelmintic resistance (AR) is increasing, and little is known about the molecular and genetic causes of resistance for most drugs. The free-living roundworm Caenorhabditis elegans has proven to be a tractable model to understand AR, where studies have led to the identification of molecular targets of all major anthelmintic drug classes. Here, we used genetically diverse C. elegans strains to perform dose-response analyses across 26 anthelmintic drugs that represent the three major anthelmintic drug classes (benzimidazoles, macrocyclic lactones, and nicotinic acetylcholine receptor agonists) in addition to seven other anthelmintic classes. First, we found that C. elegans strains displayed similar anthelmintic responses within drug classes and significant variation across drug classes. Next, we compared the effective concentration estimates to induce a 10% maximal response (EC10) and slope estimates of each dose-response curve of each strain to the laboratory reference strain, which enabled the identification of anthelmintics with population-wide differences to understand how genetics contribute to AR. Because genetically diverse strains displayed differential susceptibilities within and across anthelmintics, we show that C. elegans is a useful model for screening potential nematicides before applications to helminths. Third, we quantified the levels of anthelmintic response variation caused by genetic differences among individuals (heritability) to each drug and observed a significant correlation between exposure closest to the EC10 and the exposure that exhibited the most heritable responses. These results suggest drugs to prioritize in genome-wide association studies, which will enable the identification of AR genes.
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Affiliation(s)
- Amanda O. Shaver
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Janneke Wit
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Clayton M. Dilks
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Timothy A. Crombie
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Hanchen Li
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Raffi V. Aroian
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Erik C. Andersen
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
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10
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Thorn CS, Maness RW, Hulke JM, Delmore KE, Criscione CD. Population genomics of helminth parasites. J Helminthol 2023; 97:e29. [PMID: 36927601 DOI: 10.1017/s0022149x23000123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
Next generation sequencing technologies have facilitated a shift from a few targeted loci in population genetic studies to whole genome approaches. Here, we review the types of questions and inferences regarding the population biology and evolution of parasitic helminths being addressed within the field of population genomics. Topics include parabiome, hybridization, population structure, loci under selection and linkage mapping. We highlight various advances, and note the current trends in the field, particularly a focus on human-related parasites despite the inherent biodiversity of helminth species. We conclude by advocating for a broader application of population genomics to reflect the taxonomic and life history breadth displayed by helminth parasites. As such, our basic knowledge about helminth population biology and evolution would be enhanced while the diversity of helminths in itself would facilitate population genomic comparative studies to address broader ecological and evolutionary concepts.
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Affiliation(s)
- C S Thorn
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - R W Maness
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - J M Hulke
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - K E Delmore
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - C D Criscione
- Department of Biology, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
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11
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Hong WD, O’Neill PM, Taylor MJ, Turner JD, Ward SA, Gusovsky F, Benayoud F, Shibuguchi N, Girish D, Fang FG, Talabhakthla RK, Vaddi A, Challa C, Reddy KSA, Kalla V, Srinivasa Rao S, Nagireddi DMK, Patel J, Khile AS. Transformation of the Manufacturing Process from Discovery to Kilogram Scale for AWZ1066S: A Highly Specific Anti- Wolbachia Drug Candidate for a Short-Course Treatment of Filariasis. Org Process Res Dev 2023. [DOI: 10.1021/acs.oprd.2c00167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- W. David Hong
- Department of Chemistry, University of Liverpool, L69 7ZD Liverpool, United Kingdom
| | - Paul M. O’Neill
- Department of Chemistry, University of Liverpool, L69 7ZD Liverpool, United Kingdom
| | - Mark J. Taylor
- Research Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Joseph D. Turner
- Research Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Stephen A. Ward
- Research Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, United Kingdom
| | - Fabian Gusovsky
- G2D2 Eisai Inc., 35 Cambridgepark Drive, Cambridge, Massachusetts 02140, United States
| | - Farid Benayoud
- Eisai AiM Institute, Eisai, Inc., Andover, Massachusetts 01810, United States
| | - Nao Shibuguchi
- Analytical Research, Pharmaceutical Science & Technology, CFU, Medicine Development Center, Eisai Co. Ltd., 5-1-3-Tokodai, Tsukuba-shi, Ibaraki 300-2635, Japan
| | - Dixit Girish
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Francis Gerard Fang
- Eisai AiM Institute, Eisai, Inc., Andover, Massachusetts 01810, United States
| | - Ravi Kumar Talabhakthla
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Anand Vaddi
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Chiranjeevi Challa
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Karri Satya Ammi Reddy
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Vijay Kalla
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Sugandham Srinivasa Rao
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Durga Mahesh Kumar Nagireddi
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Jayesh Patel
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
| | - Anil Shahaji Khile
- Eisai Pharmaceuticals India Pvt. Ltd., Ramky Pharma City, (SEZ), Plot Nos.96, 97, 98,124 &126, Parawada, Visakhapatnam, Andhra Pradesh 531019, India
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12
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Gandasegui J, Onwuchekwa C, Krolewiecki AJ, Doyle SR, Pullan RL, Enbiale W, Kepha S, Hatherell HA, van Lieshout L, Cambra-Pellejà M, Escola V, Muñoz J. Ivermectin and albendazole coadministration: opportunities for strongyloidiasis control. THE LANCET. INFECTIOUS DISEASES 2022; 22:e341-e347. [PMID: 35850127 DOI: 10.1016/s1473-3099(22)00369-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 05/24/2022] [Accepted: 05/27/2022] [Indexed: 06/15/2023]
Abstract
In 2020, WHO recognised the importance of strongyloidiasis alongside soil-transmitted helminths (STH) in their 2021-30 roadmap, which aspires to target Strongyloides stercoralis with preventive chemotherapy by use of ivermectin. Combination treatment with both albendazole, the primary drug used to treat STH, and ivermectin, would improve the efficiency of mass drug administration targeting both STH and S stercoralis. In this Personal View, we discuss the challenges and opportunities towards the development of an efficient control programme for strongyloidiasis, particularly if it is to run concurrently with STH control. We argue the need to define the prevalence threshold to implement preventive chemotherapy for S stercoralis, the target populations and optimal dosing schedules, and discuss the added benefits of a fixed-dose coformulation of ivermectin and albendazole. Implementation of an efficient control programme will require improvements to current diagnostics, and validation of new diagnostics, to target and monitor S stercoralis infections, and consideration of the challenges of multispecies diagnostics for S stercoralis and STH control. Finally, the evolution of ivermectin resistance represents a credible risk to control S stercoralis; we argue that genome-wide approaches, together with improved genome resources, are needed to characterise and prevent the emergence of resistance. Overcoming these challenges will help to reduce strongyloidiasis burden and enhance the feasibility of controlling it worldwide.
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Affiliation(s)
- Javier Gandasegui
- Barcelona Institute for Global Health, Hospital Clínic Universitat de Barcelona, Barcelona, Spain
| | - Chukwuemeka Onwuchekwa
- Barcelona Institute for Global Health, Hospital Clínic Universitat de Barcelona, Barcelona, Spain
| | - Alejandro J Krolewiecki
- Barcelona Institute for Global Health, Hospital Clínic Universitat de Barcelona, Barcelona, Spain; Instituto de Investigaciones de Enfermedades Tropicales, Universidad Nacional de Salta, Orán, Argentina
| | | | - Rachel L Pullan
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Wendemagegn Enbiale
- Bahir Dar University, College of Medicine and Health Science, Bahir Dar, Ethiopia; Amsterdam UMC, University of Amsterdam, Department of Dermatology, Amsterdam Institute for Infection and Immunity, Academic Medical Centre, Amsterdam, Netherlands
| | - Stella Kepha
- Eastern and Southern Africa Centre of International Parasite Control, Nairobi, Kenya; Medical Research Institute, Nairobi, Kenya
| | - Hollie Ann Hatherell
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Lisette van Lieshout
- Department of Parasitology, Leiden University Medical Centre, Leiden, Netherlands
| | - María Cambra-Pellejà
- Instituto de Ganadería de Montaña, Consejo Superior de Investigaciones Científicas Universidad de León, Grulleros, Spain; Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad de León, Campus de Vegazana, León, Spain
| | | | - José Muñoz
- Barcelona Institute for Global Health, Hospital Clínic Universitat de Barcelona, Barcelona, Spain.
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13
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Doyle SR, Laing R, Bartley D, Morrison A, Holroyd N, Maitland K, Antonopoulos A, Chaudhry U, Flis I, Howell S, McIntyre J, Gilleard JS, Tait A, Mable B, Kaplan R, Sargison N, Britton C, Berriman M, Devaney E, Cotton JA. Genomic landscape of drug response reveals mediators of anthelmintic resistance. Cell Rep 2022; 41:111522. [PMID: 36261007 PMCID: PMC9597552 DOI: 10.1016/j.celrep.2022.111522] [Citation(s) in RCA: 26] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Revised: 07/11/2022] [Accepted: 09/26/2022] [Indexed: 11/18/2022] Open
Abstract
Like other pathogens, parasitic helminths can rapidly evolve resistance to drug treatment. Understanding the genetic basis of anthelmintic drug resistance in parasitic nematodes is key to tracking its spread and improving the efficacy and sustainability of parasite control. Here, we use an in vivo genetic cross between drug-susceptible and multi-drug-resistant strains of Haemonchus contortus in a natural host-parasite system to simultaneously map resistance loci for the three major classes of anthelmintics. This approach identifies new alleles for resistance to benzimidazoles and levamisole and implicates the transcription factor cky-1 in ivermectin resistance. This gene is within a locus under selection in ivermectin-resistant populations worldwide; expression analyses and functional validation using knockdown experiments support that cky-1 is associated with ivermectin survival. Our work demonstrates the feasibility of high-resolution forward genetics in a parasitic nematode and identifies variants for the development of molecular diagnostics to combat drug resistance in the field.
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Affiliation(s)
- Stephen R Doyle
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK.
| | - Roz Laing
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK.
| | - David Bartley
- Moredun Research Institute, Penicuik, Midlothian EH26 0PZ, UK
| | - Alison Morrison
- Moredun Research Institute, Penicuik, Midlothian EH26 0PZ, UK
| | - Nancy Holroyd
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
| | - Kirsty Maitland
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Alistair Antonopoulos
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Umer Chaudhry
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Ilona Flis
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Sue Howell
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Jennifer McIntyre
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - John S Gilleard
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, Faculty of Veterinary Medicine, University of Calgary, Calgary T2N 1N4, Canada
| | - Andy Tait
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Barbara Mable
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - Ray Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Neil Sargison
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh EH25 9RG, UK
| | - Collette Britton
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | | | - Eileen Devaney
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G61 1QH, UK
| | - James A Cotton
- Wellcome Sanger Institute, Hinxton, Cambridgeshire CB10 1SA, UK
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14
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Tagboto S, Orish V. Drug development for onchocerciasis-the past, the present and the future. FRONTIERS IN TROPICAL DISEASES 2022. [DOI: 10.3389/fitd.2022.953061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Onchocerciasis affects predominantly rural communities in Africa, and with small foci in South America and the Yemen. The disease is a major cause of blindness and other significant morbidity and mortality. Control programs have achieved a major impact on the incidence and prevalence of onchocerciasis by interrupting transmission with vector control programs, and treatment with mass drug administration using the microfilaricide ivermectin. Over the last few decades, several microfilaricides have been developed. This initially included diethylcarbamazine, which had significant side effects and is no longer used as such. Ivermectin which is a safe and highly effective microfilaricide and moxidectin which is a longer acting microfilaricide are presently recognized therapies. Suramin was the first effective macrofilaricide but was prohibitively toxic. Certain antibiotics including doxycycline can help eliminate adult worms by targeting its endosymbiont bacteria, Wolbachia pipientis. However, the dosing regimens may make this difficult to use as part of a mass disease control program in endemic areas. It is now widely recognized that treatments that are able to kill or permanently sterilize adult filarial worms should help achieve the elimination of this disease. We summarize in detail the historic drug development in onchocerciasis, including prospective future candidate drugs.
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15
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Liu W, McNeilly TN, Mitchell M, Burgess STG, Nisbet AJ, Matthews JB, Babayan SA. Vaccine-induced time- and age-dependent mucosal immunity to gastrointestinal parasite infection. NPJ Vaccines 2022; 7:78. [PMID: 35798788 PMCID: PMC9262902 DOI: 10.1038/s41541-022-00501-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 06/13/2022] [Indexed: 11/10/2022] Open
Abstract
Individuals vary broadly in their response to vaccination and subsequent challenge infection, with poor vaccine responders causing persistence of both infection and transmission in populations. Yet despite having substantial economic and societal impact, the immune mechanisms that underlie such variability, especially in infected tissues, remain poorly understood. Here, to characterise how antihelminthic immunity at the mucosal site of infection developed in vaccinated lambs, we inserted gastric cannulae into the abomasa of three-month- and six-month-old lambs and longitudinally analysed their local immune response during subsequent challenge infection. The vaccine induced broad changes in pre-challenge abomasal immune profiles and reduced parasite burden and egg output post-challenge, regardless of age. However, age affected how vaccinated lambs responded to infection across multiple immune pathways: adaptive immune pathways were typically age-dependent. Identification of age-dependent and age-independent protective immune pathways may help refine the formulation of vaccines, and indicate specificities of pathogen-specific immunity more generally.
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Affiliation(s)
- Wei Liu
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK
| | - Tom N McNeilly
- The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK.
| | - Mairi Mitchell
- The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK
| | - Stewart T G Burgess
- The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK
| | - Alasdair J Nisbet
- The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK
| | - Jacqueline B Matthews
- The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK.,Roslin Technologies Limited, Roslin Innovation Centre, University of Edinburgh, Easter Bush, Scotland, EH25 9RG, UK
| | - Simon A Babayan
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, Scotland, UK. .,The Moredun Research Institute, Pentlands Science Park, Scotland, EH26 0PZ, UK.
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16
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Laing R, Doyle SR, McIntyre J, Maitland K, Morrison A, Bartley DJ, Kaplan R, Chaudhry U, Sargison N, Tait A, Cotton JA, Britton C, Devaney E. Transcriptomic analyses implicate neuronal plasticity and chloride homeostasis in ivermectin resistance and response to treatment in a parasitic nematode. PLoS Pathog 2022; 18:e1010545. [PMID: 35696434 PMCID: PMC9232149 DOI: 10.1371/journal.ppat.1010545] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 06/24/2022] [Accepted: 04/23/2022] [Indexed: 12/28/2022] Open
Abstract
The antiparasitic drug ivermectin plays an essential role in human and animal health globally. However, ivermectin resistance is widespread in veterinary helminths and there are growing concerns of sub-optimal responses to treatment in related helminths of humans. Despite decades of research, the genetic mechanisms underlying ivermectin resistance are poorly understood in parasitic helminths. This reflects significant uncertainty regarding the mode of action of ivermectin in parasitic helminths, and the genetic complexity of these organisms; parasitic helminths have large, rapidly evolving genomes and differences in evolutionary history and genetic background can confound comparisons between resistant and susceptible populations. We undertook a controlled genetic cross of a multi-drug resistant and a susceptible reference isolate of Haemonchus contortus, an economically important gastrointestinal nematode of sheep, and ivermectin-selected the F2 population for comparison with an untreated F2 control. RNA-seq analyses of male and female adults of all populations identified high transcriptomic differentiation between parental isolates, which was significantly reduced in the F2, allowing differences associated specifically with ivermectin resistance to be identified. In all resistant populations, there was constitutive upregulation of a single gene, HCON_00155390:cky-1, a putative pharyngeal-expressed transcription factor, in a narrow locus on chromosome V previously shown to be under ivermectin selection. In addition, we detected sex-specific differences in gene expression between resistant and susceptible populations, including constitutive upregulation of a P-glycoprotein, HCON_00162780:pgp-11, in resistant males only. After ivermectin selection, we identified differential expression of genes with roles in neuronal function and chloride homeostasis, which is consistent with an adaptive response to ivermectin-induced hyperpolarisation of neuromuscular cells. Overall, we show the utility of a genetic cross to identify differences in gene expression that are specific to ivermectin selection and provide a framework to better understand ivermectin resistance and response to treatment in parasitic helminths. Parasitic helminths (worms) infect people and animals throughout the world and are largely controlled with mass administration of anthelmintic drugs. There are a very limited number of anthelmintics available and parasitic helminths can rapidly develop resistance to these drugs. Ivermectin is a widely used anthelmintic in both humans and animals, but resistance is now widespread in the veterinary field. We crossed ivermectin resistant and ivermectin susceptible parasitic helminths and treated them with ivermectin or left them as untreated controls. This provided resistant and susceptible populations with a similar genetic background with which to study differences in gene expression associated with ivermectin resistance. We identified upregulation of a gene with no previous association with drug resistance (HCON_00155390:cky-1) in male and female worms in all resistant populations. This gene is thought to be expressed in the helminth pharynx (mouthpart) and, in mammals, plays a role in controlling nerve function and protecting nerves from damage. This is consistent with the known effects of ivermectin in inhibiting helminth feeding through pharyngeal paralysis and may implicate a novel mechanism that allows resistant worms to survive treatment.
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Affiliation(s)
- Roz Laing
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
| | | | - Jennifer McIntyre
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Kirsty Maitland
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | | | - Ray Kaplan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, United States of America
| | - Umer Chaudhry
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Neil Sargison
- Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Andy Tait
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Collette Britton
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Eileen Devaney
- Institute of Biodiversity Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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17
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Bakajika D, Kanza EM, Opoku NO, Howard HM, Mambandu GL, Nyathirombo A, Nigo MM, Kennedy KK, Masembe SL, Mumbere M, Kataliko K, Bolay KM, Attah SK, Olipoh G, Asare S, Vaillant M, Halleux CM, Kuesel AC. Effect of a single dose of 8 mg moxidectin or 150 μg/kg ivermectin on O. volvulus skin microfilariae in a randomized trial: Differences between areas in the Democratic Republic of the Congo, Liberia and Ghana and impact of intensity of infection. PLoS Negl Trop Dis 2022; 16:e0010079. [PMID: 35476631 PMCID: PMC9084535 DOI: 10.1371/journal.pntd.0010079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 05/09/2022] [Accepted: 03/13/2022] [Indexed: 11/21/2022] Open
Abstract
Background Our study in CDTI-naïve areas in Nord Kivu and Ituri (Democratic Republic of the Congo, DRC), Lofa County (Liberia) and Nkwanta district (Ghana) showed that a single 8 mg moxidectin dose reduced skin microfilariae density (microfilariae/mg skin, SmfD) better and for longer than a single 150μg/kg ivermectin dose. We now analysed efficacy by study area and pre-treatment SmfD (intensity of infection, IoI). Methodology/Principal findings Four and three IoI categories were defined for across-study and by-study area analyses, respectively. We used a general linear model to analyse SmfD 1, 6, 12 and 18 months post-treatment, a logistic model to determine the odds of undetectable SmfD from month 1 to month 6 (UD1-6), month 12 (UD1-12) and month 18 (UD1-18), and descriptive statistics to quantitate inter-interindividual response differences. Twelve months post-treatment, treatment differences (difference in adjusted geometric mean SmfD after moxidectin and ivermectin in percentage of the adjusted geometric mean SmfD after ivermectin treatment) were 92.9%, 90.1%, 86.8% and 84.5% in Nord Kivu, Ituri, Lofa and Nkwanta, and 74.1%, 84.2%, 90.0% and 95.4% for participants with SmfD 10–20, ≥20-<50, ≥50-<80, ≥80, respectively. Ivermectin’s efficacy was lower in Ituri and Nkwanta than Nord Kivu and Lofa (p≤0.002) and moxidectin’s efficacy lower in Nkwanta than Nord Kivu, Ituri and Lofa (p<0.006). Odds ratios for UD1-6, UD1-12 or UD1-18 after moxidectin versus ivermectin treatment exceeded 7.0. Suboptimal response (SmfD 12 months post-treatment >40% of pre-treatment SmfD) occurred in 0%, 0.3%, 1.6% and 3.9% of moxidectin and 12.1%, 23.7%, 10.8% and 28.0% of ivermectin treated participants in Nord Kivu, Ituri, Lofa and Nkwanta, respectively. Conclusions/Significance The benefit of moxidectin vs ivermectin treatment increased with pre-treatment IoI. The possibility that parasite populations in different areas have different drug susceptibility without prior ivermectin selection pressure needs to be considered and further investigated. Clinical Trial Registration Registered on 14 November 2008 in Clinicaltrials.gov (ID: NCT00790998). Onchocerciasis or river blindness is a parasitic disease primarily in sub-Saharan Africa and Yemen. It can cause debilitating morbidity including severe itching, skin changes, visual impairment and even blindness. Many years of control efforts, today primarily based on mass administration of ivermectin (MDA) in endemic communities, have reduced morbidity and the percentage of infected individuals so that elimination of parasite transmission is now planned. WHO estimated that in 2020 more than 239 million people required MDA. Ivermectin may not be sufficiently efficacious to achieve elimination everywhere. Our study in areas in Liberia, Ghana and the Democratic Republic of the Congo where MDA had not been implemented yet showed that one treatment with 8 mg moxidectin reduced parasite levels in the skin better and for longer than one treatment with 150 μg/kg ivermectin, the dose used during MDA. Here we show that people with higher numbers of parasites in the skin benefited more from moxidectin treatment than those with lower numbers and that the efficacy of ivermectin and moxidectin differed between study areas. Provided WHO and countries include moxidectin in guidelines and policies, this information could help decisions on when and where to use moxidectin.
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Affiliation(s)
- Didier Bakajika
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Eric M. Kanza
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | | | - Hayford M. Howard
- Clinical Research Center, Liberia Institute for Biomedical Research, Bolahun, Liberia
| | - Germain L. Mambandu
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Amos Nyathirombo
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Maurice M. Nigo
- Centre de Recherche en Maladies Tropicale de l’Ituri, Hôpital Générale de Référence de Rethy, Ituri, Democratic Republic of the Congo Democratic Republic of the Congo (DRC)
| | - Kambale Kasonia Kennedy
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Safari L. Masembe
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Mupenzi Mumbere
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Kambale Kataliko
- Centre de Recherche Clinique de Butembo, Université Catholique du Graben, Site Horizon, Butembo, Nord Kivu, Democratic Republic of the Congo (DRC)
| | - Kpehe M. Bolay
- Clinical Research Center, Liberia Institute for Biomedical Research, Bolahun, Liberia
| | - Simon K. Attah
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - George Olipoh
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - Sampson Asare
- Onchocerciasis Chemotherapy Research Center, Hohoe, Ghana
| | - Michel Vaillant
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Grand Duchy of Luxembourg
| | - Christine M. Halleux
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
- * E-mail:
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18
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Baltrušis P, Doyle SR, Halvarsson P, Höglund J. Genome-wide analysis of the response to ivermectin treatment by a Swedish field population of Haemonchus contortus. Int J Parasitol Drugs Drug Resist 2022; 18:12-19. [PMID: 34959200 PMCID: PMC8718930 DOI: 10.1016/j.ijpddr.2021.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/20/2021] [Accepted: 12/20/2021] [Indexed: 11/24/2022]
Abstract
Haemonchus contortus is a pathogenic gastrointestinal nematode of small ruminants and, in part due to its capacity to develop resistance to drugs, contributes to significant losses in the animal production sector worldwide. Despite decades of research, comparatively little is known about the specific mechanism(s) driving resistance to drugs such as ivermectin in this species. Here we describe a genome-wide approach to detect evidence of selection by ivermectin treatment in a field population of H. contortus from Sweden, using parasites sampled from the same animals before and seven days after ivermectin exposure followed by whole-genome sequencing. Despite an 89% reduction in parasites recovered after treatment measured by the fecal egg count reduction test, the surviving population was highly genetically similar to the population before treatment, suggesting that resistance has likely evolved over time and that resistance alleles are present on diverse haplotypes. Pairwise gene and SNP frequency comparisons indicated the highest degree of differentiation was found at the terminal end of chromosome 4, whereas the most striking difference in nucleotide diversity was observed in a region on chromosome 5 previously reported to harbor a major quantitative trait locus involved in ivermectin resistance. These data provide novel insight into the genome-wide effect of ivermectin selection in a field population as well as confirm the importance of the previously established quantitative trait locus in the development of resistance to ivermectin.
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Affiliation(s)
- Paulius Baltrušis
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, P.O. Box 7036, Uppsala, Sweden.
| | - Stephen R Doyle
- Wellcome Sanger Institute, Hinxton, Cambridgeshire, CB10 1SA, UK
| | - Peter Halvarsson
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, P.O. Box 7036, Uppsala, Sweden
| | - Johan Höglund
- Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, P.O. Box 7036, Uppsala, Sweden
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19
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Pharmacokinetics of oral moxidectin in individuals with Onchocerca volvulus infection. PLoS Negl Trop Dis 2022; 16:e0010005. [PMID: 35333880 PMCID: PMC8986118 DOI: 10.1371/journal.pntd.0010005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 04/06/2022] [Accepted: 03/02/2022] [Indexed: 11/19/2022] Open
Abstract
Background Onchocerciasis (“river blindness”), is a neglected tropical disease caused by the filarial nematode Onchocerca volvulus and transmitted to humans through repeated bites by infective blackflies of the genus Simulium. Moxidectin was approved by the United States Food and Drug Administration in 2018 for the treatment of onchocerciasis in people at least 12 years of age. The pharmacokinetics of orally administered moxidectin in 18- to 60-year-old men and women infected with Onchocerca volvulus were investigated in a single-center, ivermectin-controlled, double-blind, randomized, single-ascending-dose, ascending severity of infection study in Ghana. Methodology/Principal findings Participants were randomized to either a single dose of 2, 4 or 8 mg moxidectin or ivermectin. Pharmacokinetic samples were collected prior to dosing and at intervals up to 12 months post-dose from 33 and 34 individuals treated with 2 and 4 mg moxidectin, respectively and up to 18 months post-dose from 31 individuals treated with 8 mg moxidectin. Moxidectin plasma concentrations were determined using high-performance liquid chromatography with fluorescence detection. Moxidectin plasma AUC0-∞ (2 mg: 26.7–31.7 days*ng/mL, 4 mg: 39.1–60.0 days*ng/mL, 8 mg: 99.5–129.0 days*ng/mL) and Cmax (2mg, 16.2 to17.3 ng/mL, 4 mg: 33.4 to 35.0 ng/mL, 8 mg: 55.7 to 74.4 ng/mL) were dose-proportional and independent of severity of infection. Maximum plasma concentrations were achieved 4 hours after drug administration. The mean terminal half-lives of moxidectin were 20.6, 17.7, and 23.3 days at the 2, 4 and 8 mg dose levels, respectively. Conclusion/Significance We found no relationship between severity of infection (mild, moderate or severe) and exposure parameters (AUC0-∞ and Cmax), T1/2 and Tmax for moxidectin. Tmax, volume of distribution (V/F) and oral clearance (CL/F) are similar to those in healthy volunteers from Europe. From a pharmacokinetic perspective, moxidectin is an attractive long-acting therapeutic option for the treatment of human onchocerciasis. The 2017 Global Burden of Disease Study estimated 20.9 million individuals with onchocerciasis, primarily in Africa. Onchocercal vision impairment/blindness and skin disease (e.g., skin pigment loss, debilitating itching) impact the social and economic life of infected individuals and their communities. This motivates onchocerciasis elimination efforts, today primarily through annual or biannual ivermectin treatment of affected communities. Despite progress towards elimination in many areas, others are not progressing well towards elimination and may require alternative treatment strategies. Moxidectin, approved by the United States Food and Drug Administration in 2018 for treatment of onchocerciasis in people at least 12 years old, could be an alternative. How the amount of a drug in the body changes over time is important for choosing a dose and treatment regimen and for regulatory approval. We measured moxidectin blood levels in 18 to 60 year old men and women with onchocerciasis. We found that moxidectin blood levels peaked around three-four hours after ingestion, that moxidectin stayed in the body for a long time (i.e., its elimination half-life was around 20 days) and that moxidectin blood levels depended on the dose, but not the infection severity as measured by the number of onchocerciasis parasites in the skin.
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20
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Willen L, Milton P, Hamley JID, Walker M, Osei-Atweneboana MY, Volf P, Basáñez MG, Courtenay O. Demographic patterns of human antibody levels to Simulium damnosum s.l. saliva in onchocerciasis-endemic areas: An indicator of exposure to vector bites. PLoS Negl Trop Dis 2022; 16:e0010108. [PMID: 35020729 PMCID: PMC8789114 DOI: 10.1371/journal.pntd.0010108] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 01/25/2022] [Accepted: 12/17/2021] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In onchocerciasis endemic areas in Africa, heterogenous biting rates by blackfly vectors on humans are assumed to partially explain age- and sex-dependent infection patterns with Onchocerca volvulus. To underpin these assumptions and further improve predictions made by onchocerciasis transmission models, demographic patterns in antibody responses to salivary antigens of Simulium damnosum s.l. are evaluated as a measure of blackfly exposure. METHODOLOGY/PRINCIPAL FINDINGS Recently developed IgG and IgM anti-saliva immunoassays for S. damnosum s.l. were applied to blood samples collected from residents in four onchocerciasis endemic villages in Ghana. Demographic patterns in antibody levels according to village, sex and age were explored by fitting generalized linear models. Antibody levels varied between villages but showed consistent patterns with age and sex. Both IgG and IgM responses declined with increasing age. IgG responses were generally lower in males than in females and exhibited a steeper decline in adult males than in adult females. No sex-specific difference was observed in IgM responses. CONCLUSIONS/SIGNIFICANCE The decline in age-specific antibody patterns suggested development of immunotolerance or desensitization to blackfly saliva antigen in response to persistent exposure. The variation between sexes, and between adults and youngsters may reflect differences in behaviour influencing cumulative exposure. These measures of antibody acquisition and decay could be incorporated into onchocerciasis transmission models towards informing onchocerciasis control, elimination, and surveillance.
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Affiliation(s)
- Laura Willen
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
- Centre for the Evaluation of Vaccinations, Vaccine and Infectious Disease Institute, University of Antwerp, Wilrijk, Belgium
- * E-mail: (LW); (OC)
| | - Philip Milton
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Jonathan I. D. Hamley
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research and Department of Pathobiology and Population Sciences, Royal Veterinary College, Hatfield, United Kingdom
| | | | - Petr Volf
- Department of Parasitology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Maria-Gloria Basáñez
- MRC Centre for Global Infectious Disease Analysis and London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom
| | - Orin Courtenay
- Zeeman Institute for Systems Biology & Infectious Disease Epidemiology Research and School of Life Sciences, University of Warwick, Coventry, United Kingdom
- * E-mail: (LW); (OC)
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21
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Treatment of Pregnant Women with Ivermectin during Mass Drug Distribution: Time to Investigate Its Safety and Potential Benefits. Pathogens 2021; 10:pathogens10121588. [PMID: 34959543 PMCID: PMC8703637 DOI: 10.3390/pathogens10121588] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Revised: 11/29/2021] [Accepted: 12/06/2021] [Indexed: 01/26/2023] Open
Abstract
To date, pregnant women are excluded from programmes delivering community-directed treatment of ivermectin (CDTI) for onchocerciasis and preventive chemotherapy of other helminthiases because of concerns over ivermectin safety during pregnancy. This systematic exclusion sustains an infection reservoir at the community level and deprives a vulnerable population from known benefits—there are indications that treating O. volvulus infected women may improve pregnancy outcomes and reduce the risk that their children develop onchocerciasis-associated morbidities. Furthermore, teratogenic effects are seen in non-clinical experiments at doses that far exceed those used in CDTI. Lastly, early, undetected and undeclared pregnancies are being systematically exposed to ivermectin in practice. Treatment of this population requires appropriate supporting evidence, for which we propose a three-pronged approach. First, to develop a roadmap defining the key steps needed to obtain regulatory clearance for the safe and effective use of ivermectin in all pregnant women who need it. Second, to conduct a randomised placebo-controlled double-blind clinical trial to evaluate the safety and benefits of ivermectin treatment in O. volvulus infected pregnant women. Such a trial should evaluate the possible effects of ivermectin in reducing adverse pregnancy outcomes and neonatal mortality, as well as in reducing the incidence of onchocerciasis-associated epilepsy. Third, to establish a pregnancy registry for women who inadvertently received ivermectin during pregnancy. This situation is not unique to ivermectin. Access to valuable therapies is often limited, delayed, or denied to pregnant women due to a lack of evidence. Concerns over protecting vulnerable people may result in harming them. We need to find acceptable ways to build robust evidence towards providing essential interventions during pregnancy.
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22
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Johnston KL, Hong WD, Turner JD, O'Neill PM, Ward SA, Taylor MJ. Anti-Wolbachia drugs for filariasis. Trends Parasitol 2021; 37:1068-1081. [PMID: 34229954 DOI: 10.1016/j.pt.2021.06.004] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/21/2021] [Accepted: 06/07/2021] [Indexed: 10/20/2022]
Abstract
The mutualistic association between Wolbachia endosymbionts and their filarial nematode hosts has been exploited as a validated drug target delivering macrofilaricidal outcomes. Limitations of existing antibiotics to scale-up have driven the search for new drugs, which are effective in shorter regimens of 7 days or less. Here, we review the last 14 years of anti-Wolbachia drug discovery by the anti-Wolbachia (A·WOL) consortium, which has screened more than two million compounds, delivering thousands of hit compounds. Refined screening models integrated with robust pharmacokinetic/pharmacodynamic (PK/PD) driven optimisation and selection strategies have delivered the first two drug candidates specifically designed to target Wolbachia. AWZ1066S and ABBV-4083 are currently progressing through clinical trials with the aim of delivering safe and effective macrofilaricides to support the elimination of onchocerciasis and lymphatic filariasis.
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Affiliation(s)
- Kelly L Johnston
- Centre for Neglected Tropical Diseases and Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK; School of Life Sciences, Institute of Systems, Molecular and Integrative Biology, University of Liverpool, Liverpool, UK
| | - W David Hong
- Department of Chemistry, University of Liverpool, Liverpool, UK
| | - Joseph D Turner
- Centre for Neglected Tropical Diseases and Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Paul M O'Neill
- Department of Chemistry, University of Liverpool, Liverpool, UK
| | - Stephen A Ward
- Centre for Neglected Tropical Diseases and Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Mark J Taylor
- Centre for Neglected Tropical Diseases and Centre for Drugs and Diagnostics, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, UK.
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24
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Berger DJ, Crellen T, Lamberton PHL, Allan F, Tracey A, Noonan JD, Kabatereine NB, Tukahebwa EM, Adriko M, Holroyd N, Webster JP, Berriman M, Cotton JA. Whole-genome sequencing of Schistosoma mansoni reveals extensive diversity with limited selection despite mass drug administration. Nat Commun 2021; 12:4776. [PMID: 34362894 PMCID: PMC8346512 DOI: 10.1038/s41467-021-24958-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 07/06/2021] [Indexed: 02/07/2023] Open
Abstract
Control and elimination of the parasitic disease schistosomiasis relies on mass administration of praziquantel. Whilst these programmes reduce infection prevalence and intensity, their impact on parasite transmission and evolution is poorly understood. Here we examine the genomic impact of repeated mass drug administration on Schistosoma mansoni populations with documented reduced praziquantel efficacy. We sequenced whole-genomes of 198 S. mansoni larvae from 34 Ugandan children from regions with contrasting praziquantel exposure. Parasites infecting children from Lake Victoria, a transmission hotspot, form a diverse panmictic population. A single round of treatment did not reduce this diversity with no apparent population contraction caused by long-term praziquantel use. We find evidence of positive selection acting on members of gene families previously implicated in praziquantel action, but detect no high frequency functionally impactful variants. As efforts to eliminate schistosomiasis intensify, our study provides a foundation for genomic surveillance of this major human parasite.
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Affiliation(s)
- Duncan J Berger
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Herts, UK.
| | - Thomas Crellen
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Poppy H L Lamberton
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK
- Institute for Biodiversity, Animal Health, and Comparative Medicine, and Wellcome Centre for Integrative Parasitology, University of Glasgow, Glasgow, UK
| | - Fiona Allan
- The Natural History Museum, Department of Life Sciences, London, UK
| | - Alan Tracey
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Jennifer D Noonan
- Institute of Parasitology, Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, Quebec, Canada
| | - Narcis B Kabatereine
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Edridah M Tukahebwa
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Moses Adriko
- Vector Borne & Neglected Tropical Disease Control Division, Ministry of Health, Kampala, Uganda
| | - Nancy Holroyd
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Joanne P Webster
- Department of Pathology and Pathogen Biology, Centre for Emerging, Endemic and Exotic Diseases, Royal Veterinary College, University of London, Herts, UK.
- Imperial College London, Department of Infectious Disease Epidemiology, London, UK.
| | - Matthew Berriman
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
| | - James A Cotton
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
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25
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Hübner MP, Townson S, Gokool S, Tagboto S, Maclean MJ, Verocai GG, Wolstenholme AJ, Frohberger SJ, Hoerauf A, Specht S, Scandale I, Harder A, Glenschek-Sieberth M, Hahnel SR, Kulke D. Evaluation of the in vitro susceptibility of various filarial nematodes to emodepside. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2021; 17:27-35. [PMID: 34339934 PMCID: PMC8347670 DOI: 10.1016/j.ijpddr.2021.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 07/19/2021] [Accepted: 07/24/2021] [Indexed: 11/25/2022]
Abstract
Filariae are vector-borne nematodes responsible for an enormous burden of disease. Human lymphatic filariasis, caused by Wuchereria bancrofti, Brugia malayi, and Brugia timori, and onchocerciasis (caused by Onchocerca volvulus) are neglected parasitic diseases of major public health significance in tropical regions. To date, therapeutic efforts to eliminate human filariasis have been hampered by the lack of a drug with sufficient macrofilaricidal and/or long-term sterilizing effects that is suitable for use in mass drug administration (MDA) programs, particularly in areas co-endemic with Loa loa, the causative agent of loiasis. Emodepside, a semi-synthetic cyclooctadepsipeptide, has been shown to have broad-spectrum efficacy against gastrointestinal nematodes in a variety of mammalian hosts, and has been approved as an active ingredient in dewormers for cats and dogs. This paper evaluates, compares (where appropriate) and summarizes the in vitro effects of emodepside against a range of filarial nematodes at various developmental stages. Emodepside inhibited the motility of all tested stages of filariae frequently used as surrogate species for preclinical investigations (Acanthocheilonema viteae, Brugia pahangi, Litomosoides sigmodontis, Onchocerca gutturosa, and Onchocerca lienalis), human-pathogenic filariae (B. malayi) and filariae of veterinary importance (Dirofilaria immitis) in a concentration-dependent manner. While motility of all filariae was inhibited, both stage- and species-specific differences were observed. However, whether these differences were detected because of stage- and/or species-specific factors or as a consequence of variations in protocol parameters among the participating laboratories (such as purification of the parasites, read-out units, composition of media, incubation conditions, duration of incubation etc.) remains unclear. This study, however, clearly shows that emodepside demonstrates broad-spectrum in vitro activity against filarial nematode species across different genera and can therefore be validated as a promising candidate for the treatment of human filariases, including onchocerciasis and lymphatic filariasis.
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Affiliation(s)
- Marc P Hübner
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.
| | - Simon Townson
- Griffin Institute (formerly Northwick Park Institute for Medical Research), London, HA1 3UJ, United Kingdom.
| | - Suzanne Gokool
- Griffin Institute (formerly Northwick Park Institute for Medical Research), London, HA1 3UJ, United Kingdom.
| | - Senyo Tagboto
- Griffin Institute (formerly Northwick Park Institute for Medical Research), London, HA1 3UJ, United Kingdom.
| | - Mary J Maclean
- National Institutes of Health, National Eye Institute, Clinical and Translational Immunology Section, Laboratory of Immunology, 10 Center Drive, Building 10, Room 10N113, Bethesda, MD, 20892, USA.
| | - Guilherme G Verocai
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, (current Address: INRAE Centre Val de Loire, 37380 Nouzilly, France), Athens, GA, 30602, USA; Department of Veterinary Pathobiology, College of Veterinary & Biomedical Sciences, Texas A&M University, 4467 TAMU College Station, TX, 77843, USA.
| | - Adrian J Wolstenholme
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, 501 D.W. Brooks Drive, (current Address: INRAE Centre Val de Loire, 37380 Nouzilly, France), Athens, GA, 30602, USA.
| | - Stefan J Frohberger
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127, Bonn, Germany.
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Venusberg-Campus 1, 53127, Bonn, Germany; German Center for Infection Research (DZIF), Partner Site Bonn-Cologne, Bonn, Germany.
| | - Sabine Specht
- Drugs for Neglected Diseases Initiative, Geneva, Switzerland.
| | - Ivan Scandale
- Drugs for Neglected Diseases Initiative, Geneva, Switzerland.
| | - Achim Harder
- Independent Scholar, Europaring 54, 51109, Cologne, Germany.
| | | | - Steffen R Hahnel
- Elanco Animal Health, Alfred-Nobel-Str. 50, 40789, Monheim, Germany.
| | - Daniel Kulke
- Elanco Animal Health, Alfred-Nobel-Str. 50, 40789, Monheim, Germany; Iowa State University, Department of Biomedical Sciences, 2008 Vet Med, Ames, IA, 50011, United States.
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26
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von Samson-Himmelstjerna G, Thompson RA, Krücken J, Grant W, Bowman DD, Schnyder M, Deplazes P. Spread of anthelmintic resistance in intestinal helminths of dogs and cats is currently less pronounced than in ruminants and horses - Yet it is of major concern. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2021; 17:36-45. [PMID: 34343829 PMCID: PMC8347694 DOI: 10.1016/j.ijpddr.2021.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 11/17/2022]
Abstract
Anthelmintic resistance (AR) has thus far only rarely been reported for intestinal helminths of dogs and cats, in contrast to parasites of livestock and horses. We highlight possible reasons for this striking and important discrepancy, including ecological, biological and genetic factors and/or intervention regimens of key intestinal helminths concerning both host groups. In view of the current knowledge related to the genetics, mechanisms and principles of AR development, we point at issues which in our view contribute to a comparatively lower risk of AR development in intestinal helminths of dogs and cats. Finally, we specify research needs and provide recommendations by which, based on the available information about AR in ruminant and equine helminths, the development of AR in dog and cat helminths may best be documented, prevented or at least postponed.
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Affiliation(s)
| | | | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Germany
| | - Warwick Grant
- Department of Physiology, Anatomy & Microbiology, La Trobe University, Australia
| | - Dwight D Bowman
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, USA
| | | | - Peter Deplazes
- Institute of Parasitology, University of Zurich, Switzerland
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27
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Forrer A, Wanji S, Obie ED, Nji TM, Hamill L, Ozano K, Piotrowski H, Dean L, Njouendou AJ, Ekanya R, Ndongmo WPC, Fung EG, Nnamdi DB, Abong RA, Beng AA, Eyong ME, Ndzeshang BL, Nkimbeng DA, Teghen S, Suireng A, Ashu EE, Kah E, Murdoch MM, Thomson R, Theobald S, Enyong P, Turner JD, Taylor MJ. Why onchocerciasis transmission persists after 15 annual ivermectin mass drug administrations in South-West Cameroon. BMJ Glob Health 2021; 6:bmjgh-2020-003248. [PMID: 33431378 PMCID: PMC7802695 DOI: 10.1136/bmjgh-2020-003248] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 11/11/2020] [Accepted: 11/27/2020] [Indexed: 12/11/2022] Open
Abstract
Introduction Onchocerciasis is targeted for elimination mainly with annual community-directed treatment with ivermectin (CDTI). High infection levels have been reported in South-West Cameroon, despite ≥15 years of CDTI. The aim of this study was to assess factors associated with continued onchocerciasis transmission and skin disease. Methods A large-scale cross-sectional study was conducted in 2017 in 20 communities in a loiasis-risk area in South-West Cameroon. A mixed-methods approach was used. Associations between infection levels, skin disease and adherence to CDTI were assessed using mixed regression modelling. Different community members’ perception and acceptability of the CDTI strategy was explored using semi-structured interviews. Results Onchocerciasis prevalence was 44.4% among 9456 participants. 17.5% of adults were systematic non-adherers and 5.9% participated in ≥75% of CDTI rounds. Skin disease affected 1/10 participants, including children. Increasing self-reported adherence to CDTI was associated with lower infection levels in participants aged ≥15 years but not in children. Adherence to CDTI was positively influenced by perceived health benefits, and negatively influenced by fear of adverse events linked with economic loss. Concern of lethal adverse events was a common reason for systematic non-adherence. Conclusion CDTI alone is unlikely to achieve elimination in those high transmission areas where low participation is commonly associated with the fear of adverse events, despite the current quasi absence of high-risk levels of loiasis. Such persisting historical memories and fear of ivermectin might impact adherence to CDTI also in areas with historical presence but current absence of loiasis. Because such issues are unlikely to be tackled by CDTI adaptive measures, alternative strategies are needed for onchocerciasis elimination where negative perception of ivermectin is an entrenched barrier to community participation in programmes.
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Affiliation(s)
- Armelle Forrer
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK
| | - Samuel Wanji
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Elisabeth Dibando Obie
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Theobald Mue Nji
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Department of Sociology and Anthropology, University of Buea, Buea, Cameroon
| | - Louise Hamill
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK
| | - Kim Ozano
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, Liverpool, UK
| | - Helen Piotrowski
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, Liverpool, UK
| | - Laura Dean
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, Liverpool, UK
| | - Abdel J Njouendou
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Relindis Ekanya
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Winston Patrick Chounna Ndongmo
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Ebua Gallus Fung
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Department of Sociology and Anthropology, University of Buea, Buea, Cameroon
| | - Dum-Buo Nnamdi
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Department of Sociology and Anthropology, University of Buea, Buea, Cameroon
| | - Raphael A Abong
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Amuam Andrew Beng
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Mathias Esum Eyong
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Bertrand L Ndzeshang
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Desmond Akumtoh Nkimbeng
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Samuel Teghen
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Anicetus Suireng
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Ernerstine Ebot Ashu
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Emmanuel Kah
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Michele M Murdoch
- Watford General Hospital, West Herts Hospitals NHS Trust, Watford, UK
| | - Rachael Thomson
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK
| | - Sally Theobald
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, Liverpool, UK
| | - Peter Enyong
- Department of Disease Control, Research Foundation for Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon.,Parasites and Vector Biology research unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Joseph D Turner
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK
| | - Mark J Taylor
- Centre for Neglected Tropical Diseases, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, UK
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Emodepside targets SLO-1 channels of Onchocerca ochengi and induces broad anthelmintic effects in a bovine model of onchocerciasis. PLoS Pathog 2021; 17:e1009601. [PMID: 34077488 PMCID: PMC8202924 DOI: 10.1371/journal.ppat.1009601] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 06/14/2021] [Accepted: 05/01/2021] [Indexed: 12/14/2022] Open
Abstract
Onchocerciasis (river blindness), caused by the filarial worm Onchocerca volvulus, is a neglected tropical disease mostly affecting sub-Saharan Africa and is responsible for >1.3 million years lived with disability. Current control relies almost entirely on ivermectin, which suppresses symptoms caused by the first-stage larvae (microfilariae) but does not kill the long-lived adults. Here, we evaluated emodepside, a semi-synthetic cyclooctadepsipeptide registered for deworming applications in companion animals, for activity against adult filariae (i.e., as a macrofilaricide). We demonstrate the equivalence of emodepside activity on SLO-1 potassium channels in Onchocerca volvulus and Onchocerca ochengi, its sister species from cattle. Evaluation of emodepside in cattle as single or 7-day treatments at two doses (0.15 and 0.75 mg/kg) revealed rapid activity against microfilariae, prolonged suppression of female worm fecundity, and macrofilaricidal effects by 18 months post treatment. The drug was well tolerated, causing only transiently increased blood glucose. Female adult worms were mostly paralyzed; however, some retained metabolic activity even in the multiple high-dose group. These data support ongoing clinical development of emodepside to treat river blindness.
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29
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Evans KS, Wit J, Stevens L, Hahnel SR, Rodriguez B, Park G, Zamanian M, Brady SC, Chao E, Introcaso K, Tanny RE, Andersen EC. Two novel loci underlie natural differences in Caenorhabditis elegans abamectin responses. PLoS Pathog 2021; 17:e1009297. [PMID: 33720993 PMCID: PMC7993787 DOI: 10.1371/journal.ppat.1009297] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 03/25/2021] [Accepted: 03/02/2021] [Indexed: 11/18/2022] Open
Abstract
Parasitic nematodes cause a massive worldwide burden on human health along with a loss of livestock and agriculture productivity. Anthelmintics have been widely successful in treating parasitic nematodes. However, resistance is increasing, and little is known about the molecular and genetic causes of resistance for most of these drugs. The free-living roundworm Caenorhabditis elegans provides a tractable model to identify genes that underlie resistance. Unlike parasitic nematodes, C. elegans is easy to maintain in the laboratory, has a complete and well annotated genome, and has many genetic tools. Using a combination of wild isolates and a panel of recombinant inbred lines constructed from crosses of two genetically and phenotypically divergent strains, we identified three genomic regions on chromosome V that underlie natural differences in response to the macrocyclic lactone (ML) abamectin. One locus was identified previously and encodes an alpha subunit of a glutamate-gated chloride channel (glc-1). Here, we validate and narrow two novel loci using near-isogenic lines. Additionally, we generate a list of prioritized candidate genes identified in C. elegans and in the parasite Haemonchus contortus by comparison of ML resistance loci. These genes could represent previously unidentified resistance genes shared across nematode species and should be evaluated in the future. Our work highlights the advantages of using C. elegans as a model to better understand ML resistance in parasitic nematodes.
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Affiliation(s)
- Kathryn S. Evans
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois, United States of America
| | - Janneke Wit
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Lewis Stevens
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Steffen R. Hahnel
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Briana Rodriguez
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Grace Park
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Mostafa Zamanian
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Shannon C. Brady
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, Illinois, United States of America
| | - Ellen Chao
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Katherine Introcaso
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Robyn E. Tanny
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Erik C. Andersen
- Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
- * E-mail:
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Abong RA, Amambo GN, Hamid AA, Enow BA, Beng AA, Nietcho FN, Nji TM, Njouendou AJ, Ritter M, Esum ME, Deribe K, Cho JF, Fombad FF, Enyong PI, Poole C, Pfarr K, Hoerauf A, Carlow C, Wanji S. The Mbam drainage system and onchocerciasis transmission post ivermectin mass drug administration (MDA) campaign, Cameroon. PLoS Negl Trop Dis 2021; 15:e0008926. [PMID: 33465080 PMCID: PMC7815102 DOI: 10.1371/journal.pntd.0008926] [Citation(s) in RCA: 7] [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: 07/12/2020] [Accepted: 10/27/2020] [Indexed: 11/19/2022] Open
Abstract
Background The impact of large scale Mass Drug Adminstration (MDA) of ivermectin on active onchocerciasis transmission by Simulium damnosum, which transmits the parasite O. volvulus is of great importance for onchocerciasis control programmes. We investigated in the Mbam river system area, the impact of MDA of ivermectin on entomological indices and also verify if there are river system factors that could have favoured the transmission of onchocerciasis in this area and contribute to the persistence of disease. We compared three independent techniques to detect Onchocerca larvae in blackflies and also analyzed the river system within 9 months post-MDA of ivermectin. Method Simulium flies were captured before and after 1, 3, 6 and 9months of ivermectin-MDA. The biting rate was determined and 41% of the flies dissected while the rest were grouped into pools of 100 flies for DNA extraction. The extracted DNA was then subjected to O-150 LAMP and real-time PCR for the detection of infection by Onchocerca species using pool screening. The river system was analysed and the water discharge compared between rainy and dry seasons. Principal findings We used human landing collection method (previously called human bait) to collect 22,274 adult female Simulium flies from Mbam River System. Of this number, 9,134 were dissected while 129 pools constituted for molecular screening. Overall biting and parous rates of 1113 flies/man/day and 24.7%, respectively, were observed. All diagnostic techniques detected similar rates of O. volvulus infection (P = 0.9252) and infectivity (P = 0.4825) at all monitoring time points. Onchocerca ochengi larvae were only detected in 2 of the 129 pools. Analysis of the river drainage revealed two hydroelectric dams constructed on the tributaries of the Mbam river were the key contributing factor to the high-water discharge during both rainy and dry seasons. Conclusion Results from fly dissection (Microscopy), real-time PCR and LAMP revealed the same trends pre- and post-MDA. The infection rate with animal Onchocerca sp was exceptionally low. The dense river system generate important breeding sites that govern the abundance of Simulium during both dry and rainy seasons. The presence of parasite strains that respond sub-optimally to an approved drug, favourable breeding sites for the vector and infected individual in an area, will surely provide conditions for continuous and persistent transmission of a disease despite a long-term control intervention. We investigated the impact of ivermectin on entomological indices within 9 months following a large-scale MDA in the Mbam river drainage. The river system factors that could have favoured abundance vector breeding and contribute to the persistence of disease transmission were also examined within the study period. We observed vector abundance and high entomological indices throughout the study period following ivermectin MDA. We also observed high water discharge along the main river of the drainage basin in both the rainy and dry seasons and this is due to the presence of two dams constructed upstream at Bamendjing and Mape to regularize the course of river Sanaga in view of generating hydroelectric power at Edea. Factors favouring continuous and persistent disease transmission are present in this drainage basin despite over 20 years of annual IVM-MDA. There is need for alternative control strategy in order to accelerate the fight against onchocerciasis in the area.
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Affiliation(s)
- Raphael Awah Abong
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Glory Ngongeh Amambo
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Ali Ahamat Hamid
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Belinda Agbor Enow
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Amuam Andrew Beng
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Franck Noel Nietcho
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
| | - Theobald Mue Nji
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
- Department of Sociology and Anthropology, University of Buea, Cameroon
| | - Abdel Jelil Njouendou
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Department of Biomedical science, Faculty of Health Sciences, University of Buea, Buea, Cameroon
| | - Manuel Ritter
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
| | - Mathias Eyong Esum
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Kebede Deribe
- Global Health and Infection Department, Brighton and Sussex Medical School, Brighton, United Kingdom
- School of Public Health, Addis Ababa University, Addis Ababa, Ethiopia
| | - Jerome Fru Cho
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Fanny Fri Fombad
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Peter Ivo Enyong
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
| | - Catherine Poole
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Kenneth Pfarr
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany
| | - Achim Hoerauf
- Institute for Medical Microbiology, Immunology and Parasitology, University Hospital Bonn, Bonn, Germany
- German Center for Infection Research (DZIF), partner site Bonn-Cologne, Bonn, Germany
| | - Clotilde Carlow
- New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Samuel Wanji
- Parasites and Vector Biology Research Unit (PAVBRU), Department of Microbiology and Parasitology, University of Buea, Buea, Cameroon
- Research Foundation in Tropical Diseases and Environment (REFOTDE), Buea, Cameroon
- * E-mail:
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Tyagi R, Bulman CA, Cho-Ngwa F, Fischer C, Marcellino C, Arkin MR, McKerrow JH, McNamara CW, Mahoney M, Tricoche N, Jawahar S, Janetka JW, Lustigman S, Sakanari J, Mitreva M. An Integrated Approach to Identify New Anti-Filarial Leads to Treat River Blindness, a Neglected Tropical Disease. Pathogens 2021; 10:71. [PMID: 33466870 PMCID: PMC7830784 DOI: 10.3390/pathogens10010071] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 01/05/2021] [Accepted: 01/11/2021] [Indexed: 11/17/2022] Open
Abstract
Filarial worms cause multiple debilitating diseases in millions of people worldwide, including river blindness. Currently available drugs reduce transmission by killing larvae (microfilariae), but there are no effective cures targeting the adult parasites (macrofilaricides) which survive and reproduce in the host for very long periods. To identify effective macrofilaricides, we carried out phenotypic screening of a library of 2121 approved drugs for clinical use against adult Brugia pahangi and prioritized the hits for further studies by integrating those results with a computational prioritization of drugs and associated targets. This resulted in the identification of 18 hits with anti-macrofilaricidal activity, of which two classes, azoles and aspartic protease inhibitors, were further expanded upon. Follow up screening against Onchocerca spp. (adult Onchocerca ochengi and pre-adult O. volvulus) confirmed activity for 13 drugs (the majority having IC50 < 10 μM), and a counter screen of a subset against L. loa microfilariae showed the potential to identify selective drugs that prevent adverse events when co-infected individuals are treated. Stage specific activity was also observed. Many of these drugs are amenable to structural optimization, and also have known canonical targets, making them promising candidates for further optimization that can lead to identifying and characterizing novel anti-macrofilarial drugs.
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Affiliation(s)
- Rahul Tyagi
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, 4523 Clayton Ave., St. Louis, MO 63110, USA;
| | - Christina A. Bulman
- Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, USA; (C.A.B.); (C.F.); (M.R.A.)
| | - Fidelis Cho-Ngwa
- ANDI Centre of Excellence for Onchocerciasis Drug Research, Biotechnology Unit, Faculty of Science, University of Buea, Buea CM-00237, Cameroon;
| | - Chelsea Fischer
- Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, USA; (C.A.B.); (C.F.); (M.R.A.)
| | - Chris Marcellino
- Division of Neurocritical Care and Hospital Neurology, Department of Neurology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA;
| | - Michelle R. Arkin
- Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, USA; (C.A.B.); (C.F.); (M.R.A.)
| | - James H. McKerrow
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA 92093, USA;
| | - Case W. McNamara
- Calibr, a Division of The Scripps Research Institute, 11119 Torrey Pines Road, La Jolla, CA 92037, USA;
| | - Matthew Mahoney
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; (M.M.); (J.W.J.)
| | - Nancy Tricoche
- Lindsley F. Kimball Research Institute, New York City, NY 10065, USA; (N.T.); (S.J.); (S.L.)
| | - Shabnam Jawahar
- Lindsley F. Kimball Research Institute, New York City, NY 10065, USA; (N.T.); (S.J.); (S.L.)
| | - James W. Janetka
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; (M.M.); (J.W.J.)
| | - Sara Lustigman
- Lindsley F. Kimball Research Institute, New York City, NY 10065, USA; (N.T.); (S.J.); (S.L.)
| | - Judy Sakanari
- Department of Pharmaceutical Chemistry, University of California San Francisco, 1700 4th Street, San Francisco, CA 94158, USA; (C.A.B.); (C.F.); (M.R.A.)
| | - Makedonka Mitreva
- Division of Infectious Diseases, Department of Medicine, Washington University School of Medicine, 4523 Clayton Ave., St. Louis, MO 63110, USA;
- McDonnell Genome Institute, Washington University School of Medicine, 4444 Forest Park Ave., St. Louis, MO 63108, USA
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Jacob B, Loum D, Munu D, Lakwo T, Byamukama E, Habomugisha P, Cupp EW, Unnasch TR. Optimization of Slash and Clear Community-Directed Control of Simulium damnosum Sensu Stricto in Northern Uganda. Am J Trop Med Hyg 2021; 104:1394-1403. [PMID: 33432900 DOI: 10.4269/ajtmh.20-1104] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 11/10/2020] [Indexed: 11/07/2022] Open
Abstract
Onchocerciasis, caused by infection with Onchocerca volvulus, has been targeted for elimination by 2030. Currently, onchocerciasis elimination programs rely primarily on mass distribution of ivermectin. However, ivermectin alone may not be sufficient to achieve elimination in some circumstances, and additional tools may be needed. Vector control has been used as a tool to control onchocerciasis, but vector control using insecticides is expensive and ecologically detrimental. Community-directed removal of the trailing vegetation blackfly larval attachment sites (slash and clear) has been shown to dramatically reduce vector biting densities. Here, we report studies to optimize the slash and clear process. Conducting slash and clear interventions at Simulium damnosum sensu stricto breeding sites located within 2 km of afflicted communities resulted in a 95% reduction in vector biting. Extending slash and clear further than 2 km resulted in no further decrease. A single intervention conducted at the first half of the rainy season resulted in a 97% reduction in biting rate, whereas an intervention conducted at the end of the rainy season resulted in a 94% reduction. Vector numbers in any of the intervention villages did not fully recover by the start of the following rainy season. These results suggest that slash and clear may offer an inexpensive and effective way to augment ivermectin distribution in the effort to eliminate onchocerciasis in Africa.
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Affiliation(s)
- Benjamin Jacob
- College of Public Health, University of South Florida, Tampa, Florida
| | - Denis Loum
- Nwoya District Local Government, Nwoya, Uganda
| | - Denis Munu
- The Carter Center, Uganda Office, Kampala, Uganda
| | - Thomson Lakwo
- Vector Control Division, Ministry of Health, Kampala, Uganda
| | | | | | - Eddie W Cupp
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
| | - Thomas R Unnasch
- Center for Global Health Infectious Disease Research, University of South Florida, Tampa, Florida
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Kotze AC, Gilleard JS, Doyle SR, Prichard RK. Challenges and opportunities for the adoption of molecular diagnostics for anthelmintic resistance. Int J Parasitol Drugs Drug Resist 2020; 14:264-273. [PMID: 33307336 PMCID: PMC7726450 DOI: 10.1016/j.ijpddr.2020.11.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2020] [Revised: 11/22/2020] [Accepted: 11/26/2020] [Indexed: 02/06/2023]
Abstract
Anthelmintic resistance is a significant threat to livestock production systems worldwide and is emerging as an important issue in companion animal parasite management. It is also an emerging concern for the control of human soil-transmitted helminths and filaria. An important aspect of managing anthelmintic resistance is the ability to utilise diagnostic tests to detect its emergence at an early stage. In host-parasite systems where resistance is already widespread, diagnostics have a potentially important role in determining those drugs that remain the most effective. The development of molecular diagnostics for anthelmintic resistance is one focus of the Consortium for Anthelmintic Resistance and Susceptibility (CARS) group. The present paper reflects discussions of this issue that occurred at the most recent meeting of the group in Wisconsin, USA, in July 2019. We compare molecular resistance diagnostics with in vivo and in vitro phenotypic methods, and highlight the advantages and disadvantages of each. We assess whether our knowledge on the identity of molecular markers for resistance towards the different drug classes is sufficient to provide some expectation that molecular tests for field use may be available in the short-to-medium term. We describe some practical aspects of such tests and how our current capabilities compare to the requirements of an 'ideal' test. Finally, we describe examples of drug class/parasite species interactions that provide the best opportunity for commercial use of molecular tests in the near future. We argue that while such prototype tests may not satisfy the requirements of an 'ideal' test, their potential to provide significant advances over currently-used phenotypic methods warrants their development as field diagnostics.
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Affiliation(s)
- Andrew C. Kotze
- CSIRO Agriculture and Food, St. Lucia, Brisbane, 4072, QLD, Australia,Corresponding author. , CSIRO Agriculture and Food, St. Lucia, Brisbane, 4072, QLD, Australia.
| | - John S. Gilleard
- Department of Comparative Biology and Experimental Medicine, Host-Parasite Interactions Program, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Stephen R. Doyle
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Roger K. Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, QC, H9X 3V9, Canada
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Hedtke SM, Zendejas-Heredia PA, Graves PM, Sheridan S, Sheel M, Fuimaono SD, Lau CL, Grant WN. Genetic epidemiology of lymphatic filariasis in American Samoa after mass drug administration. Int J Parasitol 2020; 51:137-147. [PMID: 33166540 DOI: 10.1016/j.ijpara.2020.08.009] [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: 06/18/2020] [Revised: 08/05/2020] [Accepted: 08/09/2020] [Indexed: 11/18/2022]
Abstract
Over 892 million people in 48 countries are at risk of infection by nematodes that cause lymphatic filariasis. As part of the Global Programme to Eliminate Lymphatic Filariasis, mass drug administration is distributed to communities until surveillance indicates infection rates are below target prevalence thresholds. In some countries, including American Samoa, lymphatic filariasis transmission persists despite years of mass drug administration and/or has resurged after cessation. Nothing is known about the population genetics of Wuchereria bancrofti worms in Polynesia, or whether local transmission is persisting and/or increasing due to inadequate mass drug administration coverage, expansion from residual hotspots, reintroduction from elsewhere, or a combination. We extracted DNA from microfilariae on blood slides collected during prevalence surveys in 2014 and 2016, comprising 31 pools of five microfilariae from 22 persons living in eight villages. We sequenced 1104 bp across three mitochondrial markers (ND4, COI, CYTB). We quantified parasite genetic differentiation using variant calls and estimated haplotypes using principal components analysis, F-statistics, and haplotype networks. Of the variants called, all but eight were shared across the main island of Tutuila, and three of those were from a previously described hotspot village, Fagali'i. Genotypic data did not support population genetic structure among regions or villages in 2016, although differences were observed between worms collected in Fagali'i in 2014 and those from 2016. Because estimated haplotype frequency varied between villages, these statistics suggested genetic differentiation, but were not consistent among villages. Finally, haplotype networks demonstrated American Samoan sequence clusters were related to previously published sequences from Papua New Guinea. These are, to our knowledge, the first reports of W. bancrofti genetic variation in Polynesia. The resurgent parasites circulating on the main island of American Samoa represent a single population. This study is the first step towards investigating how parasite population structure might inform strategies to manage resurgence and elimination of lymphatic filariasis.
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Affiliation(s)
- Shannon M Hedtke
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, Victoria, Australia.
| | - Patsy A Zendejas-Heredia
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia
| | - Patricia M Graves
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, Queensland, Australia
| | - Sarah Sheridan
- Department of Global Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Meru Sheel
- National Centre for Epidemiology and Population Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | | | - Colleen L Lau
- Department of Global Health, Research School of Population Health, The Australian National University, Acton, Australian Capital Territory, Australia
| | - Warwick N Grant
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Victoria, Australia; Department of Physiology, Anatomy and Microbiology, La Trobe University, Bundoora, Victoria, Australia
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Gerhard AP, Krücken J, Heitlinger E, Janssen IJI, Basiaga M, Kornaś S, Beier C, Nielsen MK, Davis RE, Wang J, von Samson-Himmelstjerna G. The P-glycoprotein repertoire of the equine parasitic nematode Parascaris univalens. Sci Rep 2020; 10:13586. [PMID: 32788636 PMCID: PMC7423980 DOI: 10.1038/s41598-020-70529-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022] Open
Abstract
P-glycoproteins (Pgp) have been proposed as contributors to the widespread macrocyclic lactone (ML) resistance in several nematode species including a major pathogen of foals, Parascaris univalens. Using new and available RNA-seq data, ten different genomic loci encoding Pgps were identified and characterized by transcriptome-guided RT-PCRs and Sanger sequencing. Phylogenetic analysis revealed an ascarid-specific Pgp lineage, Pgp-18, as well as two paralogues of Pgp-11 and Pgp-16. Comparative gene expression analyses in P. univalens and Caenorhabditis elegans show that the intestine is the major site of expression but individual gene expression patterns were not conserved between the two nematodes. In P. univalens, PunPgp-9, PunPgp-11.1 and PunPgp-16.2 consistently exhibited the highest expression level in two independent transcriptome data sets. Using RNA-Seq, no significant upregulation of any Pgp was detected following in vitro incubation of adult P. univalens with ivermectin suggesting that drug-induced upregulation is not the mechanism of Pgp-mediated ML resistance. Expression and functional analyses of PunPgp-2 and PunPgp-9 in Saccharomyces cerevisiae provide evidence for an interaction with ketoconazole and ivermectin, but not thiabendazole. Overall, this study established reliable reference gene models with significantly improved annotation for the P. univalens Pgp repertoire and provides a foundation for a better understanding of Pgp-mediated anthelmintic resistance.
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Affiliation(s)
- Alexander P Gerhard
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Jürgen Krücken
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Emanuel Heitlinger
- Institute of Biology, Molecular Parasitology, Humboldt-Universität Zu Berlin, Berlin, Germany.,Leibniz Institute for Zoo and Wildlife Research, Research Group Ecology and Evolution of Parasite Host Interactions, Berlin, Germany
| | - I Jana I Janssen
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Marta Basiaga
- Department of Zoology and Animal Welfare, University of Agriculture in Kraków, Kraków, Poland
| | - Sławomir Kornaś
- Department of Zoology and Animal Welfare, University of Agriculture in Kraków, Kraków, Poland
| | - Céline Beier
- Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany
| | - Martin K Nielsen
- Maxwell H. Gluck Equine Research Center, University of Kentucky, Lexington, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, USA
| | - Jianbin Wang
- Department of Biochemistry and Molecular Genetics, RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, USA.,Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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Dusabimana A, Bhwana D, Raimon S, Mmbando BP, Hotterbeekx A, Tepage F, Mandro M, Siewe Fodjo JN, Abrams S, Colebunders R. Ivermectin Treatment Response in Onchocerca Volvulus Infected Persons with Epilepsy: A Three-Country Short Cohort Study. Pathogens 2020; 9:pathogens9080617. [PMID: 32751060 PMCID: PMC7460326 DOI: 10.3390/pathogens9080617] [Citation(s) in RCA: 8] [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: 05/13/2020] [Revised: 07/24/2020] [Accepted: 07/27/2020] [Indexed: 11/16/2022] Open
Abstract
Despite a long history of community-directed treatment with ivermectin (CDTI), a high ongoing Onchocerca volvulus transmission is observed in certain onchocerciasis-endemic regions in Africa with a high prevalence of epilepsy. We investigated factors associated with higher microfilarial (mf) density after ivermectin treatment. Skin snips were obtained from O. volvulus-infected persons with epilepsy before, and 3 to 5 months after ivermectin treatment. Participants were enrolled from 4 study sites: Maridi (South Sudan); Logo and Aketi (Democratic Republic of Congo); and Mahenge (Tanzania). Of the 329 participants, 105 (31.9%) had a post-treatment mf density >20% of the pre-treatment value. The percentage reduction in the geometric mean mf density ranged from 69.0% (5 months after treatment) to 89.4% (3 months after treatment). A higher pre-treatment mf density was associated with increased probability of a positive skin snip after ivermectin treatment (p = 0.016). For participants with persistent microfiladermia during follow-up, a higher number of previous CDTI rounds increased the odds of having a post-treatment mf density >20% of the pre-treatment value (p = 0.006). In conclusion, the high onchocerciasis transmission in the study sites may be due to initially high infection intensity in some individuals. Whether the decreasing effect of ivermectin with increasing years of CDTI results from sub-optimal response mechanisms warrants further research.
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Affiliation(s)
- Alfred Dusabimana
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (A.H.); (J.N.S.F.); (S.A.)
| | - Dan Bhwana
- National Institute Medical Research, Tanga Centre, P.O. Box 5004 Tanga, Tanzania; (D.B.); (B.P.M.)
| | | | - Bruno P. Mmbando
- National Institute Medical Research, Tanga Centre, P.O. Box 5004 Tanga, Tanzania; (D.B.); (B.P.M.)
| | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (A.H.); (J.N.S.F.); (S.A.)
| | - Floribert Tepage
- Ministry of Health, Bas Uélé province, B.P. 105 Buta, Democratic Republic of Congo;
| | - Michel Mandro
- Provincial Health Division Ituri, Ministry of Health, Bunia, P.O. Box 57 Ituri, Democratic Republic of Congo;
| | - Joseph N. Siewe Fodjo
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (A.H.); (J.N.S.F.); (S.A.)
| | - Steven Abrams
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (A.H.); (J.N.S.F.); (S.A.)
- Interuniversity Institute for Biostatistics and statistical Bioinformatics, Data Science Institute, Hasselt University, 3590 Diepenbeek, Belgium
| | - Robert Colebunders
- Global Health Institute, University of Antwerp, Doornstraat 331, 2610 Antwerp, Belgium; (A.D.); (A.H.); (J.N.S.F.); (S.A.)
- Robert Colebunders, Global Health Institute, Gouverneur Kinsbergencentrum, University of Antwerp, Doornstraat 331, 2610 Wilrijk, Belgium
- Correspondence: ; Tel.: +32-486920149
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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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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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Boussinesq M, Enyong P, Chounna-Ndongmo P, Njouendou AJ, Pion SD, Rech A, Roberge C, Gaudriault G, Wanji S. Effects of an injectable long-acting formulation of ivermectin on Onchocerca ochengi in zebu cattle. ACTA ACUST UNITED AC 2020; 27:36. [PMID: 32420864 PMCID: PMC7233116 DOI: 10.1051/parasite/2020036] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 05/05/2020] [Indexed: 11/14/2022]
Abstract
The availability of a safe macrofilaricidal drug would help to accelerate onchocerciasis elimination. A trial was conducted in Cameroon to evaluate the effects of a subcutaneous injectable long-acting formulation of ivermectin (LAFI) on the microfilariae (mf) and adult stages of Onchocerca ochengi. Ten zebu cattle naturally infected with the parasite were injected subcutaneously with either 500 mg (group A, N = 4), or 1000 mg long-acting ivermectin (group B, N = 4) or the vehicle (group C, N = 2). Skin samples were collected from each animal before, and 6, 12, and 24 months after treatment to measure microfilarial densities (MFDs). Nodules excised before, and 6 and 12 months after treatment were examined histologically to assess the adult worms’ viability and reproductive status. Blood samples were collected at pre-determined time-points to obtain pharmacokinetic data. Before treatment, the average O. ochengi MFDs were similar in the three groups. Six months after treatment, all animals in groups A and B were free of skin mf, whereas those in group C still showed high MFDs (mean = 324.5 mf/g). Only one ivermectin-treated animal (belonging to group A) had skin mf 12 months after treatment (0.9 mf/g). At 24 months, another animal in group A showed skin mf (10.0 mf/g). The histologic examination of nodules at 6 and 12 months showed that LAFI was not macrofilaricidal but had a strong effect on embryogenesis. The new LAFI regimen might be an additional tool to accelerate the elimination of human onchocerciasis in specific settings.
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Affiliation(s)
- Michel Boussinesq
- Recherches Translationnelles sur le VIH et les Maladies Infectieuses (TransVIHMI), UMI233 IRD-U1175 INSERM-Université de Montpellier, BP 64501, 34394 Montpellier Cedex 5, France
| | - Peter Enyong
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
| | | | - Abdel-Jelil Njouendou
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
| | - Sébastien David Pion
- Recherches Translationnelles sur le VIH et les Maladies Infectieuses (TransVIHMI), UMI233 IRD-U1175 INSERM-Université de Montpellier, BP 64501, 34394 Montpellier Cedex 5, France
| | - Anthony Rech
- MedinCell S.A., 3 Rue des Frères Lumière, 34830 Jacou, France
| | | | | | - Samuel Wanji
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
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Khan S, Nisar A, Yuan J, Luo X, Dou X, Liu F, Zhao X, Li J, Ahmad H, Mehmood SA, Feng X. A Whole Genome Re-Sequencing Based GWA Analysis Reveals Candidate Genes Associated with Ivermectin Resistance in Haemonchus contortus. Genes (Basel) 2020; 11:E367. [PMID: 32231078 PMCID: PMC7230667 DOI: 10.3390/genes11040367] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 03/11/2020] [Accepted: 03/26/2020] [Indexed: 11/23/2022] Open
Abstract
The most important and broad-spectrum drug used to control the parasitic worms to date is ivermectin (IVM). Resistance against IVM has emerged in parasites, and preserving its efficacy is now becoming a serious issue. The parasitic nematode Haemonchus contortus (Rudolphi, 1803) is economically an important parasite of small ruminants across the globe, which has a successful track record in IVM resistance. There are growing evidences regarding the multigenic nature of IVM resistance, and although some genes have been proposed as candidates of IVM resistance using lower magnification of genome, the genetic basis of IVM resistance still remains poorly resolved. Using the full magnification of genome, we herein applied a population genomics approach to characterize genome-wide signatures of selection among pooled worms from two susceptible and six ivermectin-resistant isolates of H. contortus, and revealed candidate genes under selection in relation to IVM resistance. These candidates also included a previously known IVM-resistance-associated candidate gene HCON_00148840, glc-3. Finally, an RNA-interference-based functional validation assay revealed the HCON_00143950 as IVM-tolerance-associated gene in H. contortus. The possible role of this gene in IVM resistance could be detoxification of xenobiotic in phase I of xenobiotic metabolism. The results of this study further enhance our understanding on the IVM resistance and continue to provide further evidence in favor of multigenic nature of IVM resistance.
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Affiliation(s)
- Sawar Khan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Ayesha Nisar
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Jianqi Yuan
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Xiaoping Luo
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
- Veterinary Research Institute, Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Hohhot 010031, China
| | - Xueqin Dou
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Fei Liu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Xiaochao Zhao
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
| | - Junyan Li
- Veterinary Research Institute, Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Hohhot 010031, China
| | - Habib Ahmad
- Department of Genetics, Hazara University, Mansehra 21300, Pakistan
| | | | - Xingang Feng
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Key Laboratory of Animal Parasitology, Ministry of Agriculture of China, Shanghai 200241, China
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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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Hamley JID, Milton P, Walker M, Basáñez MG. Modelling exposure heterogeneity and density dependence in onchocerciasis using a novel individual-based transmission model, EPIONCHO-IBM: Implications for elimination and data needs. PLoS Negl Trop Dis 2019; 13:e0007557. [PMID: 31805049 PMCID: PMC7006940 DOI: 10.1371/journal.pntd.0007557] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2019] [Revised: 02/07/2020] [Accepted: 06/18/2019] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Density dependence in helminth establishment and heterogeneity in exposure to infection are known to drive resilience to interventions based on mass drug administration (MDA). However, the interaction between these processes is poorly understood. We developed a novel individual-based model for onchocerciasis transmission, EPIONCHO-IBM, which accounts for both processes. We fit the model to pre-intervention epidemiological data and explore parasite dynamics during MDA with ivermectin. METHODOLOGY/PRINCIPAL FINDINGS Density dependence and heterogeneity in exposure to blackfly (vector) bites were estimated by fitting the model to matched pre-intervention microfilarial prevalence, microfilarial intensity and vector biting rate data from savannah areas of Cameroon and Côte d'Ivoire/Burkina Faso using Latin hypercube sampling. Transmission dynamics during 25 years of annual and biannual ivermectin MDA were investigated. Density dependence in parasite establishment within humans was estimated for different levels of (fixed) exposure heterogeneity to understand how parametric uncertainty may influence treatment dynamics. Stronger overdispersion in exposure to blackfly bites results in the estimation of stronger density-dependent parasite establishment within humans, consequently increasing resilience to MDA. For all levels of exposure heterogeneity tested, the model predicts a departure from the functional forms for density dependence assumed in the deterministic version of the model. CONCLUSIONS/SIGNIFICANCE This is the first, stochastic model of onchocerciasis, that accounts for and estimates density-dependent parasite establishment in humans alongside exposure heterogeneity. Capturing the interaction between these processes is fundamental to our understanding of resilience to MDA interventions. Given that uncertainty in these processes results in very different treatment dynamics, collecting data on exposure heterogeneity would be essential for improving model predictions during MDA. We discuss possible ways in which such data may be collected as well as the importance of better understanding the effects of immunological responses on establishing parasites prior to and during ivermectin treatment.
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Affiliation(s)
- Jonathan I. D. Hamley
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- * E-mail:
| | - Philip Milton
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Pathobiology and Population Sciences, Royal Veterinary College, University of London, Hatfield, Untied Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research (LCNTDR), Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary’s campus), Imperial College London, London, United Kingdom
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Chevalier FD, Le Clec’h W, McDew-White M, Menon V, Guzman MA, Holloway SP, Cao X, Taylor AB, Kinung'hi S, Gouvras AN, Webster BL, Webster JP, Emery AM, Rollinson D, Garba Djirmay A, Al Mashikhi KM, Al Yafae S, Idris MA, Moné H, Mouahid G, Hart PJ, LoVerde PT, Anderson TJC. Oxamniquine resistance alleles are widespread in Old World Schistosoma mansoni and predate drug deployment. PLoS Pathog 2019; 15:e1007881. [PMID: 31652296 PMCID: PMC6834289 DOI: 10.1371/journal.ppat.1007881] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 11/06/2019] [Accepted: 09/16/2019] [Indexed: 01/10/2023] Open
Abstract
Do mutations required for adaptation occur de novo, or are they segregating within populations as standing genetic variation? This question is key to understanding adaptive change in nature, and has important practical consequences for the evolution of drug resistance. We provide evidence that alleles conferring resistance to oxamniquine (OXA), an antischistosomal drug, are widespread in natural parasite populations under minimal drug pressure and predate OXA deployment. OXA has been used since the 1970s to treat Schistosoma mansoni infections in the New World where S. mansoni established during the slave trade. Recessive loss-of-function mutations within a parasite sulfotransferase (SmSULT-OR) underlie resistance, and several verified resistance mutations, including a deletion (p.E142del), have been identified in the New World. Here we investigate sequence variation in SmSULT-OR in S. mansoni from the Old World, where OXA has seen minimal usage. We sequenced exomes of 204 S. mansoni parasites from West Africa, East Africa and the Middle East, and scored variants in SmSULT-OR and flanking regions. We identified 39 non-synonymous SNPs, 4 deletions, 1 duplication and 1 premature stop codon in the SmSULT-OR coding sequence, including one confirmed resistance deletion (p.E142del). We expressed recombinant proteins and used an in vitro OXA activation assay to functionally validate the OXA-resistance phenotype for four predicted OXA-resistance mutations. Three aspects of the data are of particular interest: (i) segregating OXA-resistance alleles are widespread in Old World populations (4.29–14.91% frequency), despite minimal OXA usage, (ii) two OXA-resistance mutations (p.W120R, p.N171IfsX28) are particularly common (>5%) in East African and Middle-Eastern populations, (iii) the p.E142del allele has identical flanking SNPs in both West Africa and Puerto Rico, suggesting that parasites bearing this allele colonized the New World during the slave trade and therefore predate OXA deployment. We conclude that standing variation for OXA resistance is widespread in S. mansoni. It has been argued that drug resistance is unlikely to spread rapidly in helminth parasites infecting humans. This is based, at least in part, on the premise that resistance mutations are rare or absent within populations prior to treatment, and take a long time to reach appreciable frequencies because helminth parasite generation time is long. This argument is critically dependent on the starting frequency of resistance alleles–if high levels of “standing variation” for resistance are present prior to deployment of treatment, resistance may spread rapidly. We examined frequencies of oxamniquine resistance alleles present in Schistosoma mansoni from Africa and the Middle East where oxamniquine has seen minimal use. We found that oxamniquine resistance alleles are widespread in the Old World, ranging from 4.29% in the Middle East to 14.91% in East African parasite populations. Furthermore, we show that resistance alleles from West African and the Caribbean schistosomes share a common origin, suggesting that these alleles travelled to the New World with S. mansoni during the transatlantic slave trade. Together, these results demonstrate extensive standing variation for oxamniquine resistance. Our results have important implications for both drug treatment policies and drug development efforts, and demonstrate the power of molecular surveillance approaches for guiding helminth control.
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Affiliation(s)
- Frédéric D. Chevalier
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
- * E-mail: (FDC); (TJCA)
| | - Winka Le Clec’h
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Marina McDew-White
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Vinay Menon
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
| | - Meghan A. Guzman
- Departments of Pathology and University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Stephen P. Holloway
- Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Xiaohang Cao
- Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Alexander B. Taylor
- Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- X-ray Crystallography Core Laboratory, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Safari Kinung'hi
- National Institute for Medical Research, Mwanza, United Republic of Tanzania
| | - Anouk N. Gouvras
- London Centre for Neglected Tropical Disease Research (LCNDTR), Imperial Collge, London, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - Bonnie L. Webster
- London Centre for Neglected Tropical Disease Research (LCNDTR), Imperial Collge, London, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - Joanne P. Webster
- London Centre for Neglected Tropical Disease Research (LCNDTR), Imperial Collge, London, United Kingdom
- Centre for Emerging, Endemic and Exotic Diseases (CEEED), Royal Veterinary College, University of London, United Kingdom
| | - Aidan M. Emery
- London Centre for Neglected Tropical Disease Research (LCNDTR), Imperial Collge, London, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - David Rollinson
- London Centre for Neglected Tropical Disease Research (LCNDTR), Imperial Collge, London, United Kingdom
- Wolfson Wellcome Biomedical Laboratories, Natural History Museum, London, United Kingdom
| | - Amadou Garba Djirmay
- Réseau International Schistosomiases Environnemental Aménagement et Lutte (RISEAL), Niamey, Niger
- World Health Organization, Geneva, Switzerland
| | - Khalid M. Al Mashikhi
- Directorate General of Health Services, Dhofar Governorate, Salalah, Sultanate of Oman
| | - Salem Al Yafae
- Directorate General of Health Services, Dhofar Governorate, Salalah, Sultanate of Oman
| | | | - Hélène Moné
- Host-Pathogen-Environment Interactions laboratory, University of Perpignan, Perpignan, France
| | - Gabriel Mouahid
- Host-Pathogen-Environment Interactions laboratory, University of Perpignan, Perpignan, France
| | - P. John Hart
- Biochemistry & Structural Biology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- X-ray Crystallography Core Laboratory, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Philip T. LoVerde
- Departments of Pathology and University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Timothy J. C. Anderson
- Texas Biomedical Research Institute, San Antonio, Texas, United States of America
- * E-mail: (FDC); (TJCA)
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The global diversity of Haemonchus contortus is shaped by human intervention and climate. Nat Commun 2019; 10:4811. [PMID: 31641125 PMCID: PMC6805936 DOI: 10.1038/s41467-019-12695-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 09/23/2019] [Indexed: 12/14/2022] Open
Abstract
Haemonchus contortus is a haematophagous parasitic nematode of veterinary interest. We have performed a survey of its genome-wide diversity using single-worm whole genome sequencing of 223 individuals sampled from 19 isolates spanning five continents. We find an African origin for the species, together with evidence for parasites spreading during the transatlantic slave trade and colonisation of Australia. Strong selective sweeps surrounding the β-tubulin locus, a target of benzimidazole anthelmintic drug, are identified in independent populations. These sweeps are further supported by signals of diversifying selection enriched in genes involved in response to drugs and other anthelmintic-associated biological functions. We also identify some candidate genes that may play a role in ivermectin resistance. Finally, genetic signatures of climate-driven adaptation are described, revealing a gene acting as an epigenetic regulator and components of the dauer pathway. These results begin to define genetic adaptation to climate in a parasitic nematode. Based on single worm whole genome sequencing, the authors here characterise the global evolution of the gastrointestinal parasite Haemonchus contortus and identify genes that play a role in drug resistance as well as climate-driven adaptations involving an epigenetic regulator.
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The World Health Organization 2030 goals for onchocerciasis: Insights and perspectives from mathematical modelling: NTD Modelling Consortium Onchocerciasis Group. Gates Open Res 2019; 3:1545. [PMID: 31723729 PMCID: PMC6820451 DOI: 10.12688/gatesopenres.13067.1] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2019] [Indexed: 11/20/2022] Open
Abstract
The World Health Organization (WHO) has embarked on a consultation process to refine the 2030 goals for priority neglected tropical diseases (NTDs), onchocerciasis among them. Current goals include elimination of transmission (EOT) by 2020 in Latin America, Yemen and selected African countries. The new goals propose that, by 2030, EOT be verified in 10 countries; mass drug administration (MDA) with ivermectin be stopped in at least one focus in 34 countries; and that the proportion of the population no longer in need of MDA be equal or greater than 25%, 50%, 75% and 100% in at least 16, 14, 12, and 10 countries, respectively. The NTD Modelling Consortium onchocerciasis teams have used EPIONCHO and ONCHOSIM to provide modelling insights into these goals. EOT appears feasible in low-moderate endemic areas with long-term MDA at high coverage (≥75%), but uncertain in areas of higher endemicity, poor coverage and adherence, and where MDA has not yet, or only recently, started. Countries will have different proportions of their endemic areas classified according to these categories, and this distribution of pre-intervention prevalence and MDA duration and programmatic success will determine the feasibility of achieving the proposed MDA cessation goals. Highly endemic areas would benefit from switching to biannual or quarterly MDA and implementing vector control where possible (determining optimal frequency and duration of anti-vectorial interventions requires more research). Areas without loiasis that have not yet initiated MDA should implement biannual (preferably with moxidectin) or quarterly MDA from the start. Areas with loiasis not previously treated would benefit from implementing test-and(not)-treat-based interventions, vector control, and anti- Wolbachia therapies, but their success will depend on the levels of screening and coverage achieved and sustained. The diagnostic performance of IgG4 Ov16 serology for assessing EOT is currently uncertain. Verification of EOT requires novel diagnostics at the individual- and population-levels.
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Schwartz RA, Al-Qubati Y, Zieleniewski Ł, Shah R, Kapila R. Onchocerciasis (river blindness): larva-induced eczema (onchodermatitis) from an important oculocutaneous tropical disease spilling over into North America and Europe. Int J Dermatol 2019; 59:1065-1070. [PMID: 31513297 DOI: 10.1111/ijd.14614] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/05/2019] [Accepted: 08/09/2019] [Indexed: 11/28/2022]
Abstract
Onchocerciasis is a leading cause of blindness in the world. It may be seen in temperate climates of the United States and Europe in immigrants and travelers from endemic regions, often linked to poverty and war. One should be aware of an incubation period that can be up to 15 months. In its early stage and throughout its course, onchocerciasis has noteworthy skin findings, facilitating diagnosis, as onchodermatitis resembles common eczema with variable degrees of papular, lichenoid, atrophic, and pigmentary alterations, features not suggestive if one is unaware of an individual's immigration and travel history. The same concept applies for the encysted worms (onchocercomas), as they tend to appear as common skin cysts and benign neoplasms. New methods can be employed to increase diagnostic sensitivity and specificity. Ivermectin is the gold standard of therapy, the use of which has almost miraculously eliminated this disease from large areas of the earth. However, its effect remains isolated to microfilariae and can be devastating in those coinfected with Loa loa. Recently, the symbiotic relationship between adult worms and Wolbachia bacteria has been discovered and, with it, the possibility of adding doxycycline as a treatment option. We also discuss coinfection with HIV and other diseases.
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Affiliation(s)
- Robert A Schwartz
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | | | - Łukasz Zieleniewski
- Nicolaus Copernicus University Ludwig Rydygier Medical College, Bydgoszcz, Poland
| | - Radhika Shah
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
| | - Rajendra Kapila
- Professor & Head, Dermatology, Rutgers New Jersey Medical School, Newark, NJ, USA
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Small ST, Labbé F, Coulibaly YI, Nutman TB, King CL, Serre D, Zimmerman PA. Human Migration and the Spread of the Nematode Parasite Wuchereria bancrofti. Mol Biol Evol 2019; 36:1931-1941. [PMID: 31077328 PMCID: PMC6735882 DOI: 10.1093/molbev/msz116] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The human disease lymphatic filariasis causes the debilitating effects of elephantiasis and hydrocele. Lymphatic filariasis currently affects the lives of 90 million people in 52 countries. There are three nematodes that cause lymphatic filariasis, Brugia malayi, Brugia timori, and Wuchereria bancrofti, but 90% of all cases of lymphatic filariasis are caused solely by W. bancrofti (Wb). Here we use population genomics to reconstruct the probable route and timing of migration of Wb strains that currently infect Africa, Haiti, and Papua New Guinea (PNG). We used selective whole genome amplification to sequence 42 whole genomes of single Wb worms from populations in Haiti, Mali, Kenya, and PNG. Our results are consistent with a hypothesis of an Island Southeast Asia or East Asian origin of Wb. Our demographic models support divergence times that correlate with the migration of human populations. We hypothesize that PNG was infected at two separate times, first by the Melanesians and later by the migrating Austronesians. The migrating Austronesians also likely introduced Wb to Madagascar where later migrations spread it to continental Africa. From Africa, Wb spread to the New World during the transatlantic slave trade. Genome scans identified 17 genes that were highly differentiated among Wb populations. Among these are genes associated with human immune suppression, insecticide sensitivity, and proposed drug targets. Identifying the distribution of genetic diversity in Wb populations and selection forces acting on the genome will build a foundation to test future hypotheses and help predict response to current eradication efforts.
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Affiliation(s)
- Scott T Small
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN
| | - Frédéric Labbé
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN
| | - Yaya I Coulibaly
- Head Filariasis Unit, NIAID-Mali ICER, University of Bamako, Bamako, Mali
| | | | - Christopher L King
- Global Health and Disease, Case Western Reserve University, Cleveland, OH
| | - David Serre
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD
| | - Peter A Zimmerman
- Global Health and Disease, Case Western Reserve University, Cleveland, OH
- Department of Biology, Case Western Reserve University, Cleveland, OH
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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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Colebunders R, Siewe Fodjo JN, Hopkins A, Hotterbeekx A, Lakwo TL, Kalinga A, Logora MY, Basáñez MG. From river blindness to river epilepsy: Implications for onchocerciasis elimination programmes. PLoS Negl Trop Dis 2019; 13:e0007407. [PMID: 31318857 PMCID: PMC6638735 DOI: 10.1371/journal.pntd.0007407] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
| | | | - Adrian Hopkins
- Neglected and Disabling Diseases of Poverty Consultant, Kent, United Kingdom
| | - An Hotterbeekx
- Global Health Institute, University of Antwerp, Antwerp, Belgium
| | - Thomson L. Lakwo
- Neglected Tropical Diseases Control Programme, Ministry of Health, Kampala, Uganda
| | - Akili Kalinga
- National institute for Medical Research, Ministry of Health, Dar es Salaam, Tanzania
| | - Makoy Yibi Logora
- Neglected Tropical Diseases Unit, Ministry of Health, Juba, South Sudan
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research and MRC Centre for Global Infectious Disease Analysis (MRC-GIDA), Imperial College London, London, United Kingdom
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Turner HC, Walker M, Pion SDS, McFarland DA, Bundy DAP, Basáñez M. Economic evaluations of onchocerciasis interventions: a systematic review and research needs. Trop Med Int Health 2019; 24:788-816. [PMID: 31013395 PMCID: PMC6617745 DOI: 10.1111/tmi.13241] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To provide a systematic review of economic evaluations that has been conducted for onchocerciasis interventions, to summarise current key knowledge and to identify research gaps. METHOD A systematic review of the literature was conducted on the 8th of August 2018 using the PubMed (MEDLINE) and ISI Web of Science electronic databases. No date or language stipulations were applied to the searches. RESULTS We identified 14 primary studies reporting the results of economic evaluations of onchocerciasis interventions, seven of which were cost-effectiveness analyses. The studies identified used a variety of different approaches to estimate the costs of the investigated interventions/programmes. Originally, the studies only quantified the benefits associated with preventing blindness. Gradually, methods improved and also captured onchocerciasis-associated skin disease. Studies found that eliminating onchocerciasis would generate billions in economic benefits. The majority of the cost-effectiveness analyses evaluated annual mass drug administration (MDA). The estimated cost per disability-adjusted life year (DALY) averted of annual MDA varies between US$3 and US$30 (cost year variable). CONCLUSIONS The cost benefit and cost effectiveness of onchocerciasis interventions have consistently been found to be very favourable. This finding provides strong evidential support for the ongoing efforts to eliminate onchocerciasis from endemic areas. Although these results are very promising, there are several important research gaps that need to be addressed as we move towards the 2020 milestones and beyond.
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Affiliation(s)
- Hugo C. Turner
- Oxford University Clinical Research UnitWellcome Africa Asia ProgrammeHo Chi Minh CityVietnam
- Centre for Tropical Medicine and Global HealthNuffield Department of MedicineUniversity of OxfordOxfordUK
| | - Martin Walker
- London Centre for Neglected Tropical Disease ResearchDepartment of Pathobiology and Population SciencesRoyal Veterinary CollegeHatfieldUK
- London Centre for Neglected Tropical Disease ResearchDepartment of Infectious Disease EpidemiologySchool of Public HealthImperial College LondonLondonUK
| | - Sébastien D. S. Pion
- Institut de Recherche pour le DéveloppementUMI 233‐INSERMU1175‐Montpellier UniversityMontpellierFrance
| | | | | | - María‐Gloria Basáñez
- London Centre for Neglected Tropical Disease ResearchDepartment of Infectious Disease EpidemiologySchool of Public HealthImperial College LondonLondonUK
- MRC Centre for Global Infectious Disease AnalysisDepartment of Infectious Disease EpidemiologySchool of Public HealthImperial College LondonLondonUK
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