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Cramer EY, Nguyen XQ, Hertz JC, Nguyen DV, Quang HH, Mendenhall IH, Lover AA. Measuring effects of ivermectin-treated cattle on potential malaria vectors in Vietnam: A cluster-randomized trial. PLoS Negl Trop Dis 2024; 18:e0012014. [PMID: 38683855 PMCID: PMC11098492 DOI: 10.1371/journal.pntd.0012014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/16/2024] [Accepted: 02/19/2024] [Indexed: 05/02/2024] Open
Abstract
BACKGROUND Malaria elimination using current tools has stalled in many areas. Ivermectin (IVM) is a broad-antiparasitic drug and mosquitocide and has been proposed as a tool for accelerating progress towards malaria elimination. Under laboratory conditions, IVM has been shown to reduce the survival of adult Anopheles populations that have fed on IVM-treated mammals. Treating cattle with IVM has been proposed as an important contribution to malaria vector management, however, the impacts of IVM in this One Health use case have been untested in field trials in Southeast Asia. METHODS Through a randomized village-based trial, this study quantified the effect of IVM-treated cattle on anopheline populations in treated vs. untreated villages in Central Vietnam. Local zebu cattle in six rural villages were included in this study. In three villages, cattle were treated with IVM at established veterinary dosages, and in three additional villages cattle were left as untreated controls. For the main study outcome, the mosquito populations in all villages were sampled using cattle-baited traps for six nights before, and six nights after a 2-day IVM-administration (intervention) period. Anopheline species were characterized using taxonomic keys. The impact of the intervention was analyzed using a difference-in-differences (DID) approach with generalized estimating equations (with negative binomial distribution and robust errors). This intervention was powered to detect a 50% reduction in total nightly Anopheles spp. vector catches from cattle-baited traps. Given the unusual diversity in anopheline populations, exploratory analyses examined taxon-level differences in the ecological population diversity. RESULTS Across the treated villages, 1,112 of 1,523 censused cows (73% overall; range 67% to 83%) were treated with IVM. In both control and treated villages, there was a 30% to 40% decrease in total anophelines captured in the post-intervention period as compared to the pre-intervention period. In the control villages, there were 1,873 captured pre-intervention and 1,079 captured during the post-intervention period. In the treated villages, there were 1,594 captured pre-intervention, and 1,101 captured during the post-intervention period. The difference in differences model analysis comparing total captures between arms was not statistically significant (p = 0.61). Secondary outcomes of vector population diversity found that in three villages (one control and two treatment) Brillouin's index increased, and in three villages (two control and one treatment) Brillouin's index decreased. When examining biodiversity by trapping-night, there were no clear trends in treated or untreated vector populations. Additionally, there were no clear trends when examining the components of biodiversity: richness and evenness. CONCLUSIONS The ability of this study to quantify the impacts of IVM treatment was limited due to unexpectedly large spatiotemporal variability in trapping rates; an area-wide decrease in trapping counts across all six villages post-intervention; and potential spillover effects. However, this study provides important data to directly inform future studies in the GMS and beyond for IVM-based vector control.
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Affiliation(s)
- Estee Y. Cramer
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Massachusetts, United States of America
| | - Xuan Quang Nguyen
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | | | - Do Van Nguyen
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | - Huynh Hong Quang
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | - Ian H. Mendenhall
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore
| | - Andrew A. Lover
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Massachusetts, United States of America
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Kobylinski KC, Tipthara P, Wamaket N, Chainarin S, Kullasakboonsri R, Sriwichai P, Phasomkusolsil S, Hanboonkunupakarn B, Jittamala P, Gemmell R, Boyle J, Wrigley S, Steele J, White NJ, Tarning J. Ivermectin metabolites reduce Anopheles survival. Sci Rep 2023; 13:8131. [PMID: 37208382 DOI: 10.1038/s41598-023-34719-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 05/05/2023] [Indexed: 05/21/2023] Open
Abstract
Ivermectin mass drug administration to humans or livestock is a potential vector control tool for malaria elimination. The mosquito-lethal effect of ivermectin in clinical trials exceeds that predicted from in vitro laboratory experiments, suggesting that ivermectin metabolites have mosquito-lethal effect. The three primary ivermectin metabolites in humans (i.e., M1 (3″-O-demethyl ivermectin), M3 (4-hydroxymethyl ivermectin), and M6 (3″-O-demethyl, 4-hydroxymethyl ivermectin) were obtained by chemical synthesis or bacterial modification/metabolism. Ivermectin and its metabolites were mixed in human blood at various concentrations, blood-fed to Anopheles dirus and Anopheles minimus mosquitoes, and mortality was observed daily for fourteen days. Ivermectin and metabolite concentrations were quantified by liquid chromatography linked with tandem mass spectrometry to confirm the concentrations in the blood matrix. Results revealed that neither the LC50 nor LC90 values differed between ivermectin and its major metabolites for An. dirus or An. minimus., Additionally, there was no substantial differences in the time to median mosquito mortality when comparing ivermectin and its metabolites, demonstrating an equal rate of mosquito killing between the compounds evaluated. These results demonstrate that ivermectin metabolites have a mosquito-lethal effect equal to the parent compound, contributing to Anopheles mortality after treatment of humans.
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Affiliation(s)
- Kevin C Kobylinski
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand.
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand.
| | - Phornpimon Tipthara
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Narenrit Wamaket
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Sittinont Chainarin
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Rattawan Kullasakboonsri
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Patchara Sriwichai
- Department of Medical Entomology, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Siriporn Phasomkusolsil
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand
| | - Borimas Hanboonkunupakarn
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Podjanee Jittamala
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
- Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
| | - Renia Gemmell
- Hypha Discovery Limited, 154B Brook Drive, Abingdon, OX14 4SD, Oxfordshire, UK
| | - John Boyle
- Hypha Discovery Limited, 154B Brook Drive, Abingdon, OX14 4SD, Oxfordshire, UK
| | - Stephen Wrigley
- Hypha Discovery Limited, 154B Brook Drive, Abingdon, OX14 4SD, Oxfordshire, UK
| | - Jonathan Steele
- Hypha Discovery Limited, 154B Brook Drive, Abingdon, OX14 4SD, Oxfordshire, UK
| | - Nicholas J White
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7BN, UK
| | - Joel Tarning
- Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Ratchathewi, Bangkok, 10400, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7BN, UK
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Eba K, Habtewold T, Asefa L, Degefa T, Yewhalaw D, Duchateau L. Effect of Ivermectin ® on survivorship and fertility of Anopheles arabiensis in Ethiopia: an in vitro study. Malar J 2023; 22:12. [PMID: 36624480 PMCID: PMC9830892 DOI: 10.1186/s12936-023-04440-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Innovative vector control tools are needed to counteract insecticide resistance and residual malaria transmission. One of such innovative methods is an ivermectin (IVM) treatment to reduce vector survival. In this study, a laboratory experiment was conducted to investigate the effect of ivermectin on survivorship, fertility and egg hatchability rate of Anopheles arabiensis in Ethiopia. METHODS An in vitro experiment was conducted using 3-5 days old An. arabiensis adults from a colony maintained at insectary of Tropical and Infectious Diseases Research Center, Jimma University (laboratory population) and Anopheles mosquitoes reared from larvae collected from natural mosquito breeding sites (wild population). The mosquitoes were allowed to feed on cattle blood treated with different doses of ivermectin (0 ng/ml, 5 ng/ml, 10 ng/ml, 20 ng/ml, 40 ng/ml and 80 ng/ml). During each feeding experiment, the mosquitoes were held in cages and blood-fed using a Hemotek feeder. Mortality and egg production were then recorded daily for up to 9 days. Time to death was analysed by a Cox frailty model with replicate as frailty term and source of mosquito (wild versus laboratory), treatment type (ivermectin vs control) and their interaction as categorical fixed effects. Kaplan Meier curves were plotted separately for wild and laboratory populations for a visual interpretation of mosquito survival as a function of treatment. RESULTS Both mosquito source and treatment had a significant effect on survival (P < 0.001), but their interaction was not significant (P = 0.197). Compared to the controls, the death hazard of An. arabiensis that fed on ivermectin-treated blood was 2.3, 3.5, 6.5, 11.5 and 17.9 times that of the control for the 5 ng/ml, 10 ng/ml, 20 ng/ml, 40 ng/ml, and 80 ng/ml dose, respectively. With respect to the number of hatched larvae, hatched pupae and emerged adults per fed mosquitoes, a significant difference was found between the control and the 5 ng/ml dose group (P < 0.001). The number of hatched larvae and pupae, and emerged adults decreased further for the 10 ng/ml dose group and falls to zero for the higher doses. CONCLUSION Treating cattle blood with ivermectin reduced mosquito survival, fertility, egg hatchability, larval development and adult emergence of An. arabiensis in all tested concentrations of ivermectin in both the wild and laboratory populations. Thus, ivermectin application in cattle could be used as a supplementary vector control method to tackle residual malaria transmission and ultimately achieve malaria elimination in Ethiopia.
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Affiliation(s)
- Kasahun Eba
- grid.411903.e0000 0001 2034 9160Department of Environmental Health Science and Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Tibebu Habtewold
- grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, UK
| | - Lechisa Asefa
- grid.411903.e0000 0001 2034 9160Department of Environmental Health Science and Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia ,grid.472427.00000 0004 4901 9087Department of Environmental Health Sciences, Bule Hora University, P.O. Box 144, Bule Hora, Ethiopia
| | - Teshome Degefa
- grid.411903.e0000 0001 2034 9160School of Medical Laboratory Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- grid.411903.e0000 0001 2034 9160School of Medical Laboratory Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia ,grid.411903.e0000 0001 2034 9160Tropical and Infectious Diseases Research Center, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Luc Duchateau
- grid.5342.00000 0001 2069 7798Biometrics Research Center, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
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Amelia-Yap ZH, Azman AS, AbuBakar S, Low VL. Streptomyces derivatives as an insecticide: Current perspectives, challenges and future research needs for mosquito control. Acta Trop 2022; 229:106381. [PMID: 35183537 DOI: 10.1016/j.actatropica.2022.106381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/16/2022] [Accepted: 02/16/2022] [Indexed: 12/13/2022]
Abstract
The pervasiveness of arboviruses in wreaking havoc on public health has lingered on international health agendas. A scarcity of mosquito-borne disease vaccines and therapies demands prompt attention, as billions of people worldwide are at risk of infections. It is widely known that vector control continues, and in some diseases, remains the only resort in suppressing disease transmissions we presently possess at its disposal. But the use of commercial insecticides is being crippled by the widespread insecticide resistance, which greatly menaces their efficacies, toxicological repercussions such as environmental pollution and human health risk. Rather, an environmentally benign technique of employing Streptomyces isolates from settings such as terrestrial soils, marine sediments, and mangrove soils for Culicidae management has recently received a lot of positive attention. Streptomyces' capacities to produce a wide range of bioactive secondary metabolites that contribute to pharmaceutical, agricultural and veterinarian, Streptomyces-derived bioactive compounds are increasingly being considered for use in vector control. Herein, we compiled all of the available datasets on the effectiveness of Streptomyces-derived compounds against major mosquito vectors of medical importance. Aedes, Anopheles, and Culex are used to assess the toxicity of crude extracts or fractions. This paper reviewed the promising ovicidal, larvicidal, and pupacidal effects of different Streptomyces strains. Notably, no research into the adulticidal effect of Streptomyces-derived compounds has yet been done. Aside from the genetic makeup, the production of secondary metabolites from Streptomyces depends on the growing conditions. And that, to optimise the maximum yield of highly potent bioactive compounds being extracted, solvents' choice is of paramount importance. Thus, both cultivation parameters and the choice of organic solvents for secondary metabolites extraction will be discussed. Furthermore, biases derived from different studies have implied the need for standardizing experimental procedures. While entomological data should be collected consistently across all studies to expedite evidence-based policymaking of bioinsecticides, the quality of data from vector control interventions - particularly the experimental design, execution, analysis, and presentation of results of vector control studies - will be thoroughly reviewed. Lastly, to promote consistency and reliability, these knowledge gaps are identified, along with a discussion of current perspectives on vector control, global bioinsecticide trends, challenges on commercializing bioinsecticides and future research needs.
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Affiliation(s)
- Zheng Hua Amelia-Yap
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Adzzie Shazleen Azman
- School of Science, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, 47500, Malaysia
| | - Sazaly AbuBakar
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Van Lun Low
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia.
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Ahmad SS, Rahi M, Saroha P, Sharma A. Ivermectin as an endectocide may boost control of malaria vectors in India and contribute to elimination. Parasit Vectors 2022; 15:20. [PMID: 35012612 PMCID: PMC8744265 DOI: 10.1186/s13071-021-05124-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/12/2021] [Indexed: 11/10/2022] Open
Abstract
Malaria constitutes one of the largest public health burdens faced by humanity. Malaria control has to be an efficient balance between diagnosis, treatment and vector control strategies. The World Health Organization currently recommends indoor residual spraying and impregnated bed nets as two malaria vector control methods that have shown robust and persistent results against endophilic and anthropophilic mosquito species. The Indian government launched the National Framework for Malaria Elimination in 2016 with the aim to achieve the elimination of malaria in a phased and strategic manner and to sustain a nation-wide malaria-free status by 2030. India is currently in a crucial phase of malaria elimination and novel vector control strategies maybe helpful in dealing with various challenges, such as vector behavioural adaptations and increasing insecticide resistance among the Anopheles populations of India. Ivermectin can be one such new tool as it is the first endectocide to be approved in both animals and humans. Trials of ivermectin have been conducted in endemic areas of Africa with promising results. In this review, we assess available data on ivermectin as an endectocide and propose that this endectocide should be explored as a vector control tool for malaria in India.
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Affiliation(s)
- Sundus Shafat Ahmad
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
| | - Manju Rahi
- Indian Council of Medical Research, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
| | - Poonam Saroha
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
| | - Amit Sharma
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
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