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Ominde KM, Kamau Y, Karisa J, Muturi MN, Kiuru C, Wanjiku C, Babu L, Yaah F, Tuwei M, Musani H, Ondieki Z, Muriu S, Mwangangi J, Chaccour C, Maia MF. A field bioassay for assessing ivermectin bio-efficacy in wild malaria vectors. Malar J 2023; 22:291. [PMID: 37777725 PMCID: PMC10542238 DOI: 10.1186/s12936-023-04718-9] [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: 03/06/2023] [Accepted: 09/13/2023] [Indexed: 10/02/2023] Open
Abstract
BACKGROUND Ivermectin (IVM) mass drug administration is a candidate complementary malaria vector control tool. Ingestion of blood from IVM treated hosts results in reduced survival in mosquitoes. Estimating bio-efficacy of IVM on wild-caught mosquitoes requires they ingest the drug in a blood meal either through a membrane or direct feeding on a treated host. The latter, has ethical implications, and the former results in low feeding rates. Therefore, there is a need to develop a safe and effective method for IVM bio-efficacy monitoring in wild mosquitoes. METHODS Insectary-reared Anopheles gambiae s.s. were exposed to four IVM doses: 85, 64, 43, 21 ng/ml, and control group (0 ng/ml) in three different solutions: (i) blood, (ii) 10% glucose, (iii) four ratios (1:1, 1:2, 1:4, 1:8) of blood in 10% glucose, and fed through filter paper. Wild-caught An. gambiae s.l. were exposed to 85, 43 and 21 ng/ml IVM in blood and 1:4 ratio of blood-10% glucose mixture. Survival was monitored for 28 days and a pool of mosquitoes from each cohort sacrificed immediately after feeding and weighed to determine mean weight of each meal type. RESULTS When administered in glucose solution, mosquitocidal effect of IVM was not comparable to the observed effects when similar concentrations were administered in blood. Equal concentrations of IVM administered in blood resulted in pronounced reductions in mosquito survival compared to glucose solution only. However, by adding small amounts of blood to glucose solution, mosquito mortality rates increased resulting in similar effects to what was observed during blood feeding. CONCLUSION Bio-efficacy of ivermectin is strongly dependent on mode of drug delivery to the mosquito and likely influenced by digestive processes. The assay developed in this study is a good candidate for field-based bio-efficacy monitoring: wild mosquitoes readily feed on the solution, the assay can be standardized using pre-selected concentrations and by not involving treated blood hosts (human or animal) variation in individual pharmacokinetic profiles as well as ethical issues are bypassed. Meal volumes did not explain the difference in the lethality of IVM across the different meal types necessitating further research on the underlying mechanisms.
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Affiliation(s)
- Kelly M Ominde
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Department of Biological Sciences, and Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya.
| | - Yvonne Kamau
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jonathan Karisa
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, and Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| | - Martha N Muturi
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Caroline Wanjiku
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lawrence Babu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Festus Yaah
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mercy Tuwei
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, and Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| | - Haron Musani
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Zedekiah Ondieki
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Simon Muriu
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Department of Biological Sciences, and Pwani University Biosciences Research Centre, Pwani University, Kilifi, Kenya
| | - Joseph Mwangangi
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Carlos Chaccour
- ISGlobal, Barcelona, Spain
- Ciberinfec, Madrid, Spain
- Faculty of Medicine, Universidad de Navarra, Pamplona, Spain
| | - Marta F Maia
- Department of Biosciences, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya.
- Centre for Global Health and Tropical Medicine and Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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2
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Foy BD, Some A, Magalhaes T, Gray L, Rao S, Sougue E, Jackson CL, Kittelson J, Slater HC, Bousema T, Da O, Coulidiaty AGV, Colt M, Wade M, Richards K, Some AF, Dabire RK, Parikh S. Repeat Ivermectin Mass Drug Administrations for Malaria Control II: Protocol for a Double-blind, Cluster-Randomized, Placebo-Controlled Trial for the Integrated Control of Malaria. JMIR Res Protoc 2023; 12:e41197. [PMID: 36939832 PMCID: PMC10132043 DOI: 10.2196/41197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 01/31/2023] [Accepted: 01/31/2023] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND The gains made against malaria have stagnated since 2015, threatened further by increasing resistance to insecticides and antimalarials. Improvement in malaria control necessitates a multipronged strategy, which includes the development of novel tools. One such tool is mass drug administration (MDA) with endectocides, primarily ivermectin, which has shown promise in reducing malaria transmission through lethal and sublethal impacts on the mosquito vector. OBJECTIVE The primary objective of the study is to assess the impact of repeated ivermectin MDA on malaria incidence in children aged ≤10 years. METHODS Repeat Ivermectin MDA for Malaria Control II is a double-blind, placebo-controlled, cluster-randomized, and parallel-group trial conducted in a setting with intense seasonal malaria transmission in Southwest Burkina Faso. The study included 14 discrete villages: 7 (50%) randomized to receive standard measures (seasonal malaria chemoprevention [SMC] and bed net use for children aged 3 to 59 months) and placebo, and 7 (50%) randomized to receive standard measures and monthly ivermectin MDA at 300 μg/kg for 3 consecutive days, provided under supervision to all eligible village inhabitants, over 2 successive rainy seasons. Nonpregnant individuals >90 cm in height were eligible for ivermectin MDA, and cotreatment with ivermectin and SMC was not permitted. The primary outcome is malaria incidence in children aged ≤10 years, as assessed by active case surveillance. The secondary safety outcome of repeated ivermectin MDA was assessed through active and passive adverse event monitoring. RESULTS The trial intervention was conducted from July to November in 2019 and 2020, with additional sampling of humans and mosquitoes occurring through February 2022 to assess postintervention changes in transmission patterns. Additional human and entomological assessments were performed over the 2 years in a subset of households from 6 cross-sectional villages. A subset of individuals underwent additional sampling in 2020 to characterize ivermectin pharmacokinetics and pharmacodynamics. Analysis and unblinding will commence once the database has been completed, cleaned, and locked. CONCLUSIONS Our trial represents the first study to directly assess the impact of a novel approach for malaria control, ivermectin MDA as a mosquitocidal agent, layered into existing standard-of-care interventions. The study was designed to leverage the current SMC deployment infrastructure and will provide evidence regarding the additional benefit of ivermectin MDA in reducing malaria incidence in children. TRIAL REGISTRATIONS ClinicalTrials.gov NCT03967054; https://clinicaltrials.gov/ct2/show/NCT03967054 and Pan African Clinical Trials Registry PACT201907479787308; https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=8219. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID) DERR1-10.2196/41197.
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Affiliation(s)
- Brian D Foy
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Anthony Some
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - Tereza Magalhaes
- Department of Entomology, Texas A&M University, College Station, TX, United States
- Department of Preventive and Social Medicine, School of Medicine, Universidade Federal da Bahia, Salvador, Brazil
| | - Lyndsey Gray
- Center for Vector-Borne Infectious Diseases, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, United States
| | - Sangeeta Rao
- Department of Clinical Sciences, Colorado State University, Fort Collins, CO, United States
| | - Emmanuel Sougue
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - Conner L Jackson
- Department of Biostatistics and Informatics, University of Colorado School of Public Health, Aurora, CO, United States
| | - John Kittelson
- Department of Biostatistics and Informatics, University of Colorado School of Public Health, Aurora, CO, United States
| | - Hannah C Slater
- Malaria and Neglected Tropical Diseases, Program for Appropriate Technology in Health, Seattle, WA, United States
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, Netherlands
| | - Ollo Da
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - A Gafar V Coulidiaty
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - McKenzie Colt
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | - Martina Wade
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | - Kacey Richards
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
| | - A Fabrice Some
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - Roch K Dabire
- Institut de Recherche en Sciences de la Santé, Direction Régionale de l'Ouest, Bobo-Dioulasso, Burkina Faso
| | - Sunil Parikh
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, United States
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Chaccour C, Casellas A, Hammann F, Ruiz-Castillo P, Nicolas P, Montaña J, Mael M, Selvaraj P, Duthaler U, Mrema S, Kakolwa M, Lyimo I, Okumu F, Marathe A, Schürch R, Elobolobo E, Sacoor C, Saute F, Xia K, Jones C, Rist C, Maia M, Rabinovich NR. BOHEMIA: Broad One Health Endectocide-based Malaria Intervention in Africa-a phase III cluster-randomized, open-label, clinical trial to study the safety and efficacy of ivermectin mass drug administration to reduce malaria transmission in two African settings. Trials 2023; 24:128. [PMID: 36810194 PMCID: PMC9942013 DOI: 10.1186/s13063-023-07098-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 01/17/2023] [Indexed: 02/23/2023] Open
Abstract
BACKGROUND Residual malaria transmission is the result of adaptive mosquito behavior that allows malaria vectors to thrive and sustain transmission in the presence of good access to bed nets or insecticide residual spraying. These behaviors include crepuscular and outdoor feeding as well as intermittent feeding upon livestock. Ivermectin is a broadly used antiparasitic drug that kills mosquitoes feeding on a treated subject for a dose-dependent period. Mass drug administration with ivermectin has been proposed as a complementary strategy to reduce malaria transmission. METHODS A cluster randomized, parallel arm, superiority trial conducted in two settings with distinct eco-epidemiological conditions in East and Southern Africa. There will be three groups: human intervention, consisting of a dose of ivermectin (400 mcg/kg) administered monthly for 3 months to all the eligible population in the cluster (>15 kg, non-pregnant and no medical contraindication); human and livestock intervention, consisting human treatment as above plus treatment of livestock in the area with a single dose of injectable ivermectin (200 mcg/kg) monthly for 3 months; and controls, consisting of a dose of albendazole (400 mg) monthly for 3 months. The main outcome measure will be malaria incidence in a cohort of children under five living in the core of each cluster followed prospectively with monthly RDTs DISCUSSION: The second site for the implementation of this protocol has changed from Tanzania to Kenya. This summary presents the Mozambique-specific protocol while the updated master protocol and the adapted Kenya-specific protocol undergo national approval in Kenya. BOHEMIA will be the first large-scale trial evaluating the impact of ivermectin-only mass drug administration to humans or humans and cattle on local malaria transmission TRIAL REGISTRATION: ClinicalTrials.gov NCT04966702 . Registered on July 19, 2021. Pan African Clinical Trials Registry PACTR202106695877303.
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Affiliation(s)
- Carlos Chaccour
- ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain. .,Universidda de Navarra, Pamplona, Spain. .,Centro de Investigación Biomédica en Red de Enfermedades Infecciosas, Madrid, Spain.
| | - Aina Casellas
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Felix Hammann
- grid.411656.10000 0004 0479 0855University Hospital of Bern, Inselspital, Bern, Switzerland
| | - Paula Ruiz-Castillo
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Patricia Nicolas
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Julia Montaña
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Mary Mael
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain
| | - Prashant Selvaraj
- grid.418309.70000 0000 8990 8592Bill and Melinda Gates Foundation, Seattle, USA
| | - Urs Duthaler
- grid.6612.30000 0004 1937 0642University Basel, Basel, Switzerland
| | - Sigilbert Mrema
- grid.414543.30000 0000 9144 642XIfakara Health Institute, Ifakara, Tanzania
| | - Mwaka Kakolwa
- grid.414543.30000 0000 9144 642XIfakara Health Institute, Ifakara, Tanzania
| | - Issa Lyimo
- grid.414543.30000 0000 9144 642XIfakara Health Institute, Ifakara, Tanzania
| | - Fredros Okumu
- grid.414543.30000 0000 9144 642XIfakara Health Institute, Ifakara, Tanzania
| | - Achla Marathe
- grid.27755.320000 0000 9136 933XUniversity of Virginia, Charlottesville, USA
| | - Roger Schürch
- grid.438526.e0000 0001 0694 4940Virginia Polytechnic Institute and State University, Blacksburg, USA
| | - Eldo Elobolobo
- grid.452366.00000 0000 9638 9567Centro de Investigação em Saúde de Manhiça, Manhica, Mozambique
| | - Charfudin Sacoor
- grid.452366.00000 0000 9638 9567Centro de Investigação em Saúde de Manhiça, Manhica, Mozambique
| | - Francisco Saute
- grid.452366.00000 0000 9638 9567Centro de Investigação em Saúde de Manhiça, Manhica, Mozambique
| | - Kang Xia
- grid.438526.e0000 0001 0694 4940Virginia Polytechnic Institute and State University, Blacksburg, USA
| | - Caroline Jones
- grid.33058.3d0000 0001 0155 5938KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - Cassidy Rist
- grid.438526.e0000 0001 0694 4940Virginia Polytechnic Institute and State University, Blacksburg, USA
| | - Marta Maia
- grid.33058.3d0000 0001 0155 5938KEMRI Wellcome Trust Research Programme, Kilifi, Kenya
| | - N. Regina Rabinovich
- grid.434607.20000 0004 1763 3517ISGlobal, Barcelona Institute for Global Health, Barcelona, Spain ,grid.38142.3c000000041936754XTH Chan Harvard School of Public Health, Boston, USA
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Kumar G, Pasi S, Yadav CP, Kaur J, Sharma A. Potential of ivermectin as an active ingredient of the attractive toxic sugar baits against the Indian malaria vectors Anopheles culicifacies and Anopheles stephensi. PEST MANAGEMENT SCIENCE 2023; 79:474-480. [PMID: 36176013 DOI: 10.1002/ps.7217] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 09/26/2022] [Accepted: 09/29/2022] [Indexed: 06/16/2023]
Abstract
BACKGROUND Attractive toxic sugar bait (ATSB) is a novel vector control tool that exploits the sugar feeding behavior of mosquitoes. The current study aims to evaluate the efficacy of ivermectin-based ATSB against insecticide susceptible and resistant strains of major Indian malaria vectors - Anopheles culicifacies and Anopheles stephensi. ATSB with different concentrations of ivermectin were tested against mosquito vectors under standard laboratory conditions. RESULTS Dose-response analysis of ivermectin-ATSB showed 7.8 and 19.8 ppm as 50% and 90% lethal concentration (LC50 and LC90 ) values for insecticide susceptible An. culicifacies. In the case of insecticide susceptible An. stephensi, the LC90 value was 35 ppm which was significantly higher in comparison to the LC90 for An. culicifacies. The LC50 of insecticide-resistant An. culicifacies and An. stephensi were 10.6 and 15.9 ppm respectively whereas LC90 values were 36.9 and 61.0. Ivermectin-ATSB resulted in 99 ± 0.8% mortality of An. culicifacies and 93 ± 3.8% mortality of An. stephensi at an ivermectin concentration of 25 ppm. In another set of experiments, the ATSB solution containing standardized dose of ivermectin was sprayed on Allysum plant and mortality of both Anopheline vectors was recorded. Here, we observed > 90% mortality in both An. stephensi and An. culicifacies. CONCLUSION Our study demonstrates the potential of ivermectin-based ATSB in killing Indian malaria vectors irrespective of the method of application. Further field trials with ivermectin containing ATSB may pave the way for its usage in the national vector control program. © 2022 Society of Chemical Industry.
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Affiliation(s)
- Gaurav Kumar
- National Institute of Malaria Research, New Delhi, India
| | - Shweta Pasi
- National Institute of Malaria Research, New Delhi, India
| | | | - Jaspreet Kaur
- National Institute of Malaria Research, New Delhi, India
| | - Amit Sharma
- National Institute of Malaria Research, New Delhi, India
- Molecular Medicine Group, International Centre for Genetic Engineering and Biotechnology, New Delhi, India
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Kositz C, Bradley J, Hutchins H, Last A, D'Alessandro U, Marks M. Broadening the range of use cases for ivermectin - a review of the evidence. Trans R Soc Trop Med Hyg 2022; 116:201-212. [PMID: 34323283 PMCID: PMC8890779 DOI: 10.1093/trstmh/trab114] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 06/30/2021] [Accepted: 07/13/2021] [Indexed: 11/12/2022] Open
Abstract
Ivermectin is a broad-spectrum antiparasitic agent that interferes with glutamate-gated chloride channels found in invertebrates but not in vertebrate species. Mass drug administration (MDA) with ivermectin-based regimes has been a mainstay of elimination efforts targeting onchocerciasis and lymphatic filariasis for more than 3 decades. More recently, interest in the use of ivermectin to control other neglected tropical diseases (NTDs) such as soil-transmitted helminths and scabies has grown. Interest has been further stimulated by the fact that ivermectin displays endectocidal efficacy against various Anopheles species capable of transmitting malaria. Therefore there is growing interest in using ivermectin MDA as a tool that might aid in the control of both malaria and several NTDs. In this review we outline the evidence base to date on these emerging indications for ivermectin MDA with reference to clinical and public health data and discuss the rationale for evaluating the range of impacts of a malaria ivermectin MDA on other NTDs.
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Affiliation(s)
- Christian Kositz
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
| | - John Bradley
- MRC International Statistics and Epidemiology Group, Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
| | - Harry Hutchins
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
| | - Anna Last
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
- Hospital for Tropical Diseases, Mortimer Market Capper Street, WC1E 6JB, London, UK
| | - Umberto D'Alessandro
- Disease Control and Elimination, Medical Research Council Unit Gambia at London School of Hygiene and Tropical Medicine, Atlantic Boulevard, Fajara, The Gambia
| | - Michael Marks
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, WC1E 7HT, London, UK
- Hospital for Tropical Diseases, Mortimer Market Capper Street, WC1E 6JB, London, UK
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6
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Safety of mass drug coadministration with ivermectin, diethylcarbamazine, albendazole, and azithromycin for the integrated treatment of neglected tropical diseases: a cluster randomized community trial. THE LANCET REGIONAL HEALTH. WESTERN PACIFIC 2022; 18:100293. [PMID: 35024646 DOI: 10.1016/j.lanwpc.2021.100293] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 08/25/2021] [Accepted: 09/15/2021] [Indexed: 11/21/2022]
Abstract
Introduction Neglected tropical diseases control programmes run separately. For settings with more than one endemic disease, combined mass drug administration (MDA) has potential practical advantages compared with separate programmes but needs confirmation of safety. We assessed the safety of combined MDA for multiple neglected tropical diseases using ivermectin, diethylcarbamazine, albendazole (IDA) and azithromycin (AZI). Methods We conducted an open-label, cluster-randomized trial involving individuals living in 34 wards (smaller administrative division) in two study sites, Namatanai District and Lihir Island, Papua New Guinea. We randomly assigned wards to the combined treatment arm (which received a single dose of the triple combination IDA and a single dose of AZI at the same visit) or the control arm (which received IDA separately followed by AZI separately one week after). All participants underwent safety assessments one day after drug administration. Methodology for collecting the adverse events (AEs) was a general question (in Namatanai) and individual questions about specific AEs (in Lihir). The primary endpoint was the prevalence of AEs. Safety of combined treatment was taken to be non-inferior to that of IDA if the upper limit of the two-sided CI for the difference in rates was equal or lower than 5%. Findings The study enrolled 15,656 participants. Of those enrolled, 7,281 (46.3%) received the combined regimen and 8,375 (53.3%) received standard treatment with IDA for lymphatic filariasis between Nov 1, 2018, and Apr 15, 2019. Of the individuals in the control group, 4,228 (50.5%) attended a second visit one week apart to receive AZI for yaws. In Namatanai, the proportion of AEs was similar in the combined group (0.8%) compared to the IDA group (1.3%, difference 0.5% [95CI -2.5% to 1.4%]) or the AZI group (3.6%, d -2.8% [95CI -8.6% to 2.8%]). In Lihir, the proportion of AEs was higher in the combined group (23.0%) compared to the IDA group (12.2%, d 10.8% [95% CI 1.5% to 20.2%]) or the AZI group (11.1%, d 11.9% [95% CI 2.7% to 21.1%]).We observed 21 (0.3%) grade-2 AEs in the combined treatment group, 33 (0.4%) in the IDA separately group, and 18 (0.2%) in the AZI separately group. No participants required treatment for any AE. We observed no deaths, serious AEs, or AEs of special interest. Interpretation In the largest trial so far involving coadministration of regimens based on IDA and AZI, the combination was safe and feasible in a population of more than 15,000 people. Combined MDA based on these two regimens opens up new potential for the control of neglected tropical diseases in the Western Pacific region.
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7
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Marathe A, Shi R, Mendez-Lopez A, Hu Z, Lewis B, Rabinovich R, Chaccour CJ, Rist C. Potential impact of 5 years of ivermectin mass drug administration on malaria outcomes in high burden countries. BMJ Glob Health 2021; 6:bmjgh-2021-006424. [PMID: 34764146 PMCID: PMC8587489 DOI: 10.1136/bmjgh-2021-006424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 10/18/2021] [Indexed: 11/03/2022] Open
Abstract
INTRODUCTION The global progress against malaria has slowed significantly since 2017. As the current malaria control tools seem insufficient to get the trend back on track, several clinical trials are investigating ivermectin mass drug administration (iMDA) as a potential additional vector control tool; however, the health impacts and cost-effectiveness of this new strategy remain unclear. METHODS We developed an analytical tool based on a full factorial experimental design to assess the potential impact of iMDA in nine high burden sub-Saharan African countries. The simulated iMDA regimen was assumed to be delivered monthly to the targeted population for 3 months each year from 2023 to 2027. A broad set of parameters of ivermectin efficacy, uptake levels and global intervention scenarios were used to predict averted malaria cases and deaths. We then explored the potential averted treatment costs, expected implementation costs and cost-effectiveness ratios under different scenarios. RESULTS In the scenario where coverage of malaria interventions was maintained at 2018 levels, we found that iMDA in these nine countries has the potential to reverse the predicted growth of malaria burden by averting 20-50 million cases and 36 000-90 000 deaths with an assumed efficacy of 20%. If iMDA has an efficacy of 40%, we predict between 40-99 million cases and 73 000-179 000 deaths will be averted with an estimated net cost per case averted between US$2 and US$7, and net cost per death averted between US$1460 and US$4374. CONCLUSION This study measures the potential of iMDA to reverse the increasing number of malaria cases for several sub-Saharan African countries. With additional efficacy information from ongoing clinical trials and country-level modifications, our analytical tool can help determine the appropriate uptake strategies of iMDA by calculating potential marginal gains and costs under different scenarios.
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Affiliation(s)
- Achla Marathe
- Network Systems Science and Advanced Computing Division, Biocomplexity Institute, University of Virginia, Charlottesville, Virginia, USA.,Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia, USA
| | - Ruoding Shi
- Department of Public Health Sciences, University of Virginia, Charlottesville, Virginia, USA
| | - Ana Mendez-Lopez
- Department of Preventive Medicine, Public Health and Microbiology, Autonomous University of Madrid, Madrid, Spain.,Barcelona Institute for Global Health, ISGlobal, Barcelona, Spain
| | - Zhihao Hu
- Department of Statistics, Virginia Tech, Blacksburg, Virginia, USA
| | - Bryan Lewis
- Network Systems Science and Advanced Computing Division, Biocomplexity Institute, University of Virginia, Charlottesville, Virginia, USA
| | | | - Carlos J Chaccour
- Barcelona Institute for Global Health, ISGlobal, Barcelona, Spain.,Universitat de Navarra, Pamplona, Spain
| | - Cassidy Rist
- Department of Population Health Sciences, Virginia Tech, Blacksburg, Virginia, USA
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8
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Singh L, Singh K. Ivermectin: A Promising Therapeutic for Fighting Malaria. Current Status and Perspective. J Med Chem 2021; 64:9711-9731. [PMID: 34242031 DOI: 10.1021/acs.jmedchem.1c00498] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Finding new chemotherapeutic interventions to treat malaria through repurposing of time-tested drugs and rigorous design of new drugs using tools of rational drug design remains one of the most sought strategies at the disposal of medicinal chemists. Ivermectin, a semisynthetic derivative of avermectin B1, is among the efficacious drugs used in mass drug administration drives employed against onchocerciasis, lymphatic filariasis, and several other parasitic diseases in humans. In this review, we present the prowess of ivermectin, a potent endectocide, in the control of malaria through vector control to reduce parasite transmission combined with efficacious chemoprevention to reduce malaria-related fatalities.
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Affiliation(s)
- Lovepreet Singh
- Department of Chemistry, UGC Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar-143 005, India
| | - Kamaljit Singh
- Department of Chemistry, UGC Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar-143 005, India
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9
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Hii J, Hustedt J, Bangs MJ. Residual Malaria Transmission in Select Countries of Asia-Pacific Region: Old Wine in a New Barrel. J Infect Dis 2021; 223:S111-S142. [PMID: 33906222 PMCID: PMC8079134 DOI: 10.1093/infdis/jiab004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Background Despite substantial reductions in malaria burden and improvement in case management, malaria remains a major public health challenge in the Asia-Pacific region. Residual malaria transmission (RMT) is the fraction of total transmission that persists after achievement of full operational coverage with effective insecticide-treated bed nets (ITNs)/long-lasting insecticidal nets (LLINs) and/or indoor residual spray interventions. There is a critical need to standardize and share best practices for entomological, anthropological, and product development investigative protocols to meet the challenges of RMT and elimination goals. Methods A systematic review was conducted to describe when and where RMT is occurring, while specifically targeting ownership and usage of ITN/LLINs, indoor residual spray application, insecticide susceptibility of vectors, and human and vector biting behavior, with a focus on nighttime activities. Results Sixty-six publications from 1995 to present met the inclusion criteria for closer review. Associations between local vector control coverage and use with behaviors of human and mosquito vectors varied by locality and circumstance. Consequently, the magnitude of RMT is insufficiently studied and analyzed with sparse estimates of individual exposure in communities, insufficient or incomplete observations of ITN/LLIN use, and the local human population movement into and from high-risk areas. Conclusions This review identified significant gaps or deficiencies that require urgent attention, namely, developing standardized procedures and methods to estimate risk exposure beyond the peridomestic setting, analytical approaches to measure key human-vector interactions, and seasonal location-specific agricultural or forest use calendars, and establishing the collection of longitudinal human and vector data close in time and location.
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Affiliation(s)
- Jeffrey Hii
- Malaria Consortium Asia, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.,College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | | | - Michael J Bangs
- Public Health and Malaria Control Department, PT Freeport Indonesia, International SOS, Jl. Kertajasa, Kuala Kencana, Papua, Indonesia.,Department of Entomology, Faculty of Agriculture, Kasertart University, Bangkok, Thailand
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10
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Omitola OO, Umunnakwe CU, Bayegun AA, Anifowose SA, Mogaji HO, Oluwole AS, Odoemene SN, Awolola TS, Osipitan AA, Sam-Wobo SO, Ekpo UF. Impacts of ivermectin mass drug administration for onchocerciasis on mosquito populations of Ogun state, Nigeria. Parasit Vectors 2021; 14:212. [PMID: 33879232 PMCID: PMC8056593 DOI: 10.1186/s13071-021-04716-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 04/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The impact of single-dose mass drug administration (MDA) of ivermectin for onchocerciasis on mosquito populations was investigated in Ogun State, Nigeria. METHODS Indoor and outdoor collection of mosquitoes was carried out in two intervention (IC) and two control communities (CC) at three different periods: pre-MDA (baseline), 2-3 days after MDA and 13-14 days after MDA. The density and parity rate of female Anopheles and Culex mosquitoes were determined and compared. Environmental and climatic data of study locations were obtained to perform generalized linear model analysis. RESULTS A total of 1399 female mosquitoes were collected, including 1227 Anopheles and 172 Culex mosquitoes. There was a similar magnitude of reduction in the indoor density of Anopheles by 29% in the IC and CC 2-3 days post-MDA but the reduction in indoor parity rate was significantly higher (p = 0.021) in the IC, reducing by more than 50%. In the IC, observation of a significant reduction at 2-3 days post-MDA was consistent for both the indoor density (1.43 to 1.02) and indoor parity rate (95.35% to 44.26%) of Anopheles mosquitoes. The indoor parity rate of Anopheles remained significantly reduced (75.86%) 13-14 post-MDA. On the other hand, the indoor density of Culex increased from 0.07 to 0.10 at 2-3 days post-MDA while the indoor parity rate of Culex did not change. The outdoor density of Anopheles in the IC increased (p = 0.394) from 0.58 to 0.90 at 2-3 days post-MDA; a similar observation was consistent for the outdoor density (2.83 to 3.90) and outdoor parity rate (70.59% to 97.44%) of Culex, while the outdoor parity rate of Anopheles reduced from 85.71 to 66.67% at 2-3 days post-MDA. A generalized linear model showed that ivermectin MDA significantly caused a reduction in both the indoor density (p < 0.001) and indoor parity rate (p = 0.003) of Anopheles in the IC. CONCLUSION Ivermectin MDA resulted in the reduction of both the survival and density of Anopheles mosquitoes. This has strong implications for malaria transmission, which depends strongly on vector survival.
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Affiliation(s)
- Olaitan Olamide Omitola
- Department of Pure and Applied Zoology, Federal University of Agriculture, Abeokuta, Ogun, Nigeria.
| | | | - Adedotun Ayodeji Bayegun
- Department of Pure and Applied Zoology, Federal University of Agriculture, Abeokuta, Ogun, Nigeria
| | | | - Hammed Oladeji Mogaji
- Department of Animal and Environmental Biology, Federal University Oye Ekiti, Ekiti, Nigeria
| | | | | | - Taiwo Sam Awolola
- Molecular Entomology and Vector Control Research Laboratory, Public Health Division, Nigeria Institute of Medical Research, Lagos, Nigeria
| | | | - Sammy Olufemi Sam-Wobo
- Department of Pure and Applied Zoology, Federal University of Agriculture, Abeokuta, Ogun, Nigeria
| | - Uwem Friday Ekpo
- Department of Pure and Applied Zoology, Federal University of Agriculture, Abeokuta, Ogun, Nigeria.
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11
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High concentrations of membrane-fed ivermectin are required for substantial lethal and sublethal impacts on Aedes aegypti. Parasit Vectors 2021; 14:9. [PMID: 33407825 PMCID: PMC7789309 DOI: 10.1186/s13071-020-04512-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 12/01/2020] [Indexed: 12/25/2022] Open
Abstract
Background With widespread insecticide resistance in mosquito vectors, there is a pressing need to evaluate alternatives with different modes of action. Blood containing the antihelminthic drug ivermectin has been shown to have lethal and sub-lethal effects on mosquitoes. Almost all work to date has been on Anopheles spp., but impacts on other anthropophagic vectors could provide new options for their control, or additional value to anti-malarial ivermectin programmes. Methods Using dose-response assays, we evaluated the effects of ivermectin delivered by membrane feeding on daily mortality (up to 14 days post-blood feed) and fecundity of an Indian strain of Aedes aegypti. Results The 7-day lethal concentration of ivermectin required to kill 50% of adult mosquitoes was calculated to be 178.6 ng/ml (95% confidence intervals 142.3–218.4) for Ae. aegypti, which is much higher than that recorded for Anopheles spp. in any previous study. In addition, significant effects on fecundity and egg hatch rates were only recorded at high ivermectin concentrations (≥ 250 ng/ul). Conclusion Our results suggest that levels of ivermectin present in human blood at current dosing regimes in mass drug administration campaigns, or even those in a recent higher-dose anti-malaria trial, are unlikely to have a substantial impact on Ae. aegypti. Moreover, owing to the strong anthropophagy of Ae. aegypti, delivery of higher levels of ivermectin in livestock blood is also unlikely to be an effective option for its control. However, other potential toxic impacts of ivermectin metabolites, accumulation in tissues, sublethal effects on behaviour, or antiviral action might increase the efficacy of ivermectin against Ae. aegypti and the arboviral diseases it transmits, and require further investigation.![]()
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12
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Harrington LC, Foy BD, Bangs MJ. Considerations for Human Blood-Feeding and Arthropod Exposure in Vector Biology Research: An Essential Tool for Investigations and Disease Control. Vector Borne Zoonotic Dis 2020; 20:807-816. [PMID: 32905735 DOI: 10.1089/vbz.2020.2620] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Eventually there may be a broadly acceptable, even perfected, substitute for the human host requirement for direct feeding experiments by arthropods, most notably mosquitoes. However, for now, direct and indirect feeding on human volunteers is an important, if not essential, tool in vector biology research (VBR). This article builds on the foundational publication by Achee et al. (2015) covering considerations for the use of human participants in VBR pursuits. The authors introduced methods involving human participation in VBR, while detailing human-landing collections (catches) as a prime example. Benedict et al. (2018) continued this theme with an overview of human participation and considerations for research that involves release of mosquito vectors into the environment. In this study, we discuss another important aspect of human use in VBR activities: considerations addressing studies that require an arthropod to feed on a live human host. Using mosquito studies as our principal example, in this study, we discuss the tremendous importance and value of this approach to support and allow study of a wide variety of factors and interactions related to our understanding of vector-borne diseases and their control. This includes establishment of laboratory colonies for test populations, characterization of essential nutrients that contribute to mosquito fitness, characterization of blood-feeding (biting) behavior and pathogen transmission, parameterization for modeling transmission dynamics, evaluation of human host attraction and/or agents that repel, and the effectiveness of antivector or parasite therapeutic drug studies.
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Affiliation(s)
| | - Brian D Foy
- Department of Microbiology, Immunology & Pathology, Arthropod-Borne and Infectious Diseases Laboratory Fort Collins, Colorado State University, Fort Collins, Colorado, USA
| | - Michael J Bangs
- Public Health & Malaria Control, PT Freeport Indonesia/International SOS, Kuala Kencana, Indonesia.,Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
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13
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Billingsley P, Binka F, Chaccour C, Foy B, Gold S, Gonzalez-Silva M, Jacobson J, Jagoe G, Jones C, Kachur P, Kobylinski K, Last A, Lavery JV, Mabey D, Mboera D, Mbogo C, Mendez-Lopez A, Rabinovich NR, Rees S, Richards F, Rist C, Rockwood J, Ruiz-Castillo P, Sattabongkot J, Saute F, Slater H, Steer A, Xia K, Zullinger R. A Roadmap for the Development of Ivermectin as a Complementary Malaria Vector Control Tool. Am J Trop Med Hyg 2020; 102:3-24. [PMID: 31971144 PMCID: PMC7008306 DOI: 10.4269/ajtmh.19-0620] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/22/2019] [Indexed: 12/14/2022] Open
Abstract
In the context of stalling progress against malaria, resistance of mosquitoes to insecticides, and residual transmission, mass drug administration (MDA) of ivermectin, an endectocide used for neglected tropical diseases (NTDs), has emerged as a promising complementary vector control method. Ivermectin reduces the life span of Anopheles mosquitoes that feed on treated humans and/or livestock, potentially decreasing malaria parasite transmission when administered at the community level. Following the publication by WHO of the preferred product characteristics for endectocides as vector control tools, this roadmap provides a comprehensive view of processes needed to make ivermectin available as a vector control tool by 2024 with a completely novel mechanism of action. The roadmap covers various aspects, which include 1) the definition of optimal dosage/regimens for ivermectin MDA in both humans and livestock, 2) the risk of resistance to the drug and environmental impact, 3) ethical issues, 4) political and community engagement, 5) translation of evidence into policy, and 6) operational aspects of large-scale deployment of the drug, all in the context of a drug given as a prevention tool acting at the community level. The roadmap reflects the insights of a multidisciplinary group of global health experts who worked together to elucidate the path to inclusion of ivermectin in the toolbox against malaria, to address residual transmission, counteract insecticide resistance, and contribute to the end of this deadly disease.
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Affiliation(s)
| | - Fred Binka
- University of Health and Allied Sciences
| | | | | | | | | | | | | | | | | | | | - Anna Last
- London School of Hygiene and Tropical Medicine
| | | | - David Mabey
- London School of Hygiene and Tropical Medicine
| | | | | | | | | | | | | | - Cassidy Rist
- Virginia-Maryland College of Veterinary Medicine at Virginia Tech
| | | | | | | | | | | | | | - Kang Xia
- School of Plant and Environmental Sciences, Virginia Tech
| | - Rose Zullinger
- US President’s Malaria Initiative/US Centers for Disease Control and Prevention
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14
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Ivermectin as a novel complementary malaria control tool to reduce incidence and prevalence: a modelling study. THE LANCET. INFECTIOUS DISEASES 2020; 20:498-508. [PMID: 31948767 DOI: 10.1016/s1473-3099(19)30633-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 09/30/2019] [Accepted: 10/21/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Ivermectin is a potential new vector control tool to reduce malaria transmission. Mosquitoes feeding on a bloodmeal containing ivermectin have a reduced lifespan, meaning they are less likely to live long enough to complete sporogony and become infectious. We aimed to estimate the effect of ivermectin on malaria transmission in various scenarios of use. METHODS We validated an existing population-level mathematical model of the effect of ivermectin mass drug administration (MDA) on the mosquito population and malaria transmission against two datasets: clinical data from a cluster- randomised trial done in Burkina Faso in 2015 wherein ivermectin was given to individuals taller than 90 cm and entomological data from a study of mosquito outcomes after ivermectin MDA for onchocerciasis or lymphatic filariasis in Burkina Faso, Senegal, and Liberia between 2008 and 2013. We extended the existing model to include a range of complementary malaria interventions (seasonal malaria chemoprevention and MDA with dihydroartemisinin-piperaquine) and to incorporate new data on higher doses of ivermectin with a longer mosquitocidal effect. We consider two ivermectin regimens: a single dose of 400 μg/kg (1 × 400 μg/kg) and three consecutive daily doses of 300 μg/kg per day (3 × 300 μg/kg). We simulated the effect of these two doses in a range of usage scenarios in different transmission settings (highly seasonal, seasonal, and perennial). We report percentage reductions in clinical incidence and slide prevalence. FINDINGS We estimate that MDA with ivermectin will reduce prevalence and incidence and is most effective in areas with highly seasonal transmission. In a highly seasonal moderate transmission setting, three rounds of ivermectin only MDA at 3 × 300 μg/kg (rounds spaced 1 month apart) and 70% coverage is predicted to reduce clinical incidence by 71% and prevalence by 34%. We predict that adding ivermectin MDA to seasonal malaria chemoprevention in this setting would reduce clinical incidence by an additional 77% in children younger than 5 years compared with seasonal malaria chemoprevention alone; adding ivermectin MDA to MDA with dihydroartemisinin-piperaquine in this setting would reduce incidence by an additional 75% and prevalence by an additional 64% (all ages) compared with MDA with dihydroartemisinin-piperaquine alone. INTERPRETATION Our modelling predictions suggest that ivermectin could be a valuable addition to the malaria control toolbox, both in areas with persistently high transmission where existing interventions are insufficient and in areas approaching elimination to prevent resurgence. FUNDING Imperial College Junior Research Fellowship.
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15
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Mekuriaw W, Balkew M, Messenger LA, Yewhalaw D, Woyessa A, Massebo F. The effect of ivermectin ® on fertility, fecundity and mortality of Anopheles arabiensis fed on treated men in Ethiopia. Malar J 2019; 18:357. [PMID: 31703736 PMCID: PMC6842263 DOI: 10.1186/s12936-019-2988-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 10/24/2019] [Indexed: 12/13/2022] Open
Abstract
Background Insecticide resistance is a growing threat to malaria vector control. Ivermectin, either administered to humans or animals, may represent an alternate strategy to reduce resistant mosquito populations. The aim of this study was to assess the residual or delayed effect of administering a single oral dose of ivermectin to humans on the survival, fecundity and fertility of Anopheles arabiensis in Ethiopia. Methods Six male volunteers aged 25–40 years (weight range 64–72 kg) were recruited; four of them received a recommended single oral dose of 12 mg ivermectin and the other two individuals were untreated controls. A fully susceptible insectary colony of An. arabiensis was fed on treated and control participants at 1, 4, 7, 10 and 13 days post ivermectin-administration. Daily mosquito mortality was recorded for 5 days. An. arabiensis fecundity and fertility were measured from day 7 post treatment, by dissection to examine the number of eggs per mosquito, and by observing larval hatching rates, respectively. Results Ivermectin treatment induced significantly higher An. arabiensis mortality on days 1 and 4, compared to untreated controls (p = 0.02 and p < 0.001, respectively). However, this effect had declined by day 7, with no significant difference in mortality between treated and control groups (p = 0.06). The mean survival time of mosquitoes fed on day 1 was 2.1 days, while those fed on day 4 survived 4.0 days. Mosquitoes fed on the treatment group at day 7 and 10 produced significantly lower numbers of eggs compared to the untreated controls (p < 0.001 and p = 0.04, respectively). An. arabiensis fed on day 7 on treated men also had lower larval hatching rates than mosquitoes fed on days 10 and 13 (p = 0.003 and p = 0.001, respectively). Conclusion A single oral dose of ivermectin given to humans can induce mortality and reduce survivorship of An. arabiensis for 7 days after treatment. Ivermectin also had a delayed effect on fecundity of An. arabiensis that took bloodmeals from treated individuals on day 7 and 10. Additional studies are warranted using wild, insecticide-resistant mosquito populations, to confirm findings and a phase III evaluation among community members in Ethiopia is needed to determine the impact of ivermectin on malaria transmission.
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Affiliation(s)
- Wondemeneh Mekuriaw
- Ethiopian Public Health Institute, Addis Ababa, Ethiopia. .,Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
| | - Meshesha Balkew
- Abt Associates, PMI Vectorlink Project in Ethiopia, Addis Ababa, Ethiopia
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Delenasaw Yewhalaw
- Tropical and Infectious Disease Research Center, Jimma University, Jimma, Ethiopia.,Department of Medical Laboratory Sciences and Pathology, College of Health Sciences, Jimma University, Jimma, Ethiopia
| | - Adugna Woyessa
- Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
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16
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Gunathilaka N, Ranathunge T, Udayanga L, Wijegunawardena A, Gilles JRL, Abeyewickreme W. Use of mechanical and behavioural methods to eliminate female Aedes aegypti and Aedes albopictus for sterile insect technique and incompatible insect technique applications. Parasit Vectors 2019; 12:148. [PMID: 30922368 PMCID: PMC6437921 DOI: 10.1186/s13071-019-3398-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Accepted: 03/13/2019] [Indexed: 02/07/2023] Open
Abstract
Background Sex separation of mosquitoes at different stages is currently being attempted to ensure the successful release of male mosquitoes in novel vector control approaches. Mechanical and behavioral techniques have been tried most frequently. Methods Batches of (n = 300) Aedes aegypti and Ae. albopictus pupae were used for standard sieving (using sieves with 1.12, 1.25, 1.40 and 1.60 mm mesh sizes) and the Fay-Morlan glass plate separation methods. Male and female separation by each method was calculated. For behavioral separation, a spiked blood meal with different concentrations (0, 2, 4, 6, 8 and 10 ppm) of ivermectin and spinosad (spinosyn, 12% w/v), were provided to a batch (n = 300) of adult Ae. aegypti and Ae. albopictus (1:1 sex ratio) followed by observation of mortality. An additional “double feeding method” involved provision of a further blood meal after 24 h, with the same concentrations of ivermectin and spinosad as the initial feeding, followed by a 48-h observation of mortality. All experiments were repeated five times. Results In the standard sieving method, the percentage of males and females separated at different pore sizes differed significantly (P < 0.05). The majority of the male pupae were collected in the 1.12 mm pore sized sieve for both Ae. aegypti (73%) and Ae. albopictus (69%) while females were retained mainly in the sieve with the pore size of 1.25 mm. In the Fay-Morlan glass plate separation, 99.0% of the Ae. aegypti and 99.2% of the Ae. albopictus introduced male pupae could be separated, but with female contaminations of 16 and 12%, respectively. Provision of a blood meal spiked with 8 ppm of ivermectin under the “double feeding” was identified as the most effective way of achieving 100% female elimination for both Aedes species. Conclusions With 100% separation, use of a spiked blood meal is a more effective method of sex separation than the mechanical methods. Application of the spiked blood meal approach as a second separation level for sexes, after applying the Fay-Morlan glass plate method, could achieve 100% sex separation of sexes whilst allowing a reduction in the amount of toxicants required.
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Affiliation(s)
- Nayana Gunathilaka
- Department of Parasitology, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.
| | - Tharaka Ranathunge
- Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka
| | - Lahiru Udayanga
- Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka.,Department of Biosystems Engineering, Faculty of Agriculture & Plantation Management, Wayamba University of Sri Lanka, Makadura, Sri Lanka
| | - Asha Wijegunawardena
- Molecular Medicine Unit, Faculty of Medicine, University of Kelaniya, Ragama, Sri Lanka
| | - Jeremie Roger Lionel Gilles
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, International Atomic Energy Agency, Vienna, Austria
| | - Wimaladharma Abeyewickreme
- Department of Paraclinical Sciences, Faculty of Medicine, Sir John Kotelawala Defence University, Ratmalana, Sri Lanka
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17
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Pasay CJ, Yakob L, Meredith HR, Stewart R, Mills PC, Dekkers MH, Ong O, Llewellyn S, Hugo RLE, McCarthy JS, Devine GJ. Treatment of pigs with endectocides as a complementary tool for combating malaria transmission by Anopheles farauti (s.s.) in Papua New Guinea. Parasit Vectors 2019; 12:124. [PMID: 30890165 PMCID: PMC6423892 DOI: 10.1186/s13071-019-3392-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 03/08/2019] [Indexed: 11/24/2022] Open
Abstract
Background Outdoor, early-biting, zoophagic behaviours by Anopheles farauti (s.s.) can compromise the effectiveness of bed nets for malaria control. In the Western Pacific region, pigs and dogs represent significant alternative blood sources for mosquitoes. Treating these animals with endectocides may impact mosquito survival and complement control measures. This hypothesis was explored using membrane feeding assays (MFAs), direct feeds on treated pigs, pharmacokinetic analyses and a transmission model. Results Ivermectin was 375-fold more mosquitocidal than moxidectin (24 h LC50 = 17.8 ng/ml vs 6.7 µg/ml) in MFAs, and reduced mosquito fecundity by > 50% at ≥ 5 ng/ml. Treatment of pigs with subcutaneous doses of 0.6 mg/kg ivermectin caused 100% mosquito mortality 8 days after administration. Lethal effects persisted for up to 15 days after administration (75% death within 10 days). Conclusion The application of these empirical data to a unique malaria transmission model that used a three-host system (humans, pigs and dogs) predicts that the application of ivermectin will cause a significant reduction in the entomological inoculation rate (EIR = 100 to 0.35). However, this is contingent on local malaria vectors sourcing a significant proportion of their blood meals from pigs. This provides significant insights on the benefits of deploying endectocides alongside long-lasting insecticide-treated nets (LLINs) to address residual malaria transmission. Electronic supplementary material The online version of this article (10.1186/s13071-019-3392-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Cielo J Pasay
- Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia.
| | - Laith Yakob
- Department of Disease Control, School of Hygiene and Tropical Medicine, London, London, UK
| | - Hannah R Meredith
- Department of Disease Control, School of Hygiene and Tropical Medicine, London, London, UK
| | - Romal Stewart
- Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Paul C Mills
- School of Veterinary Science, University of Queensland, Gatton, QLD, Australia
| | - Milou H Dekkers
- Queensland Animal Science Precinct, University of Queensland, Gatton, QLD, Australia
| | - Oselyne Ong
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Stacey Llewellyn
- Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - R Leon E Hugo
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - James S McCarthy
- Clinical Tropical Medicine, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia
| | - Gregor J Devine
- Mosquito Control Laboratory, QIMR Berghofer Medical Research Institute, Herston, QLD, Australia.
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18
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Antivirus effectiveness of ivermectin on dengue virus type 2 in Aedes albopictus. PLoS Negl Trop Dis 2018; 12:e0006934. [PMID: 30452439 PMCID: PMC6277121 DOI: 10.1371/journal.pntd.0006934] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2018] [Revised: 12/03/2018] [Accepted: 10/18/2018] [Indexed: 12/27/2022] Open
Abstract
Background Dengue fever is the most rapidly spreading mosquito-borne viral disease over the past 50 years, with a 30-fold increase in global incidence. Dengue vector control is a key component for the dengue control strategy, since no absolutely effective vaccine or drug is available yet. However, the rapid rise and spread of mosquito insecticide resistance have become major threats to the efficiency of insecticide-based vector control activities. Thus, innovative vector control tools are badly needed. This study aims to confirm the antivirus effectiveness of ivermectin on dengue virus type 2 (DENV-2) in Aedes albopictus (Skuse, 1894), then to explore its potential use in the combating to the dengue epidemics. Methods Aedes albopictus were first infected with DENV-2 in human whole blood, and at the fourth day after infectious blood feeding, they were divided into eight groups. Seven of them were held for six days with access to 0, 2, 4, 8, 16, 32 and 64 ng/ml ivermectin, respectively, and the last one was set as a historical control group, which was stored at -80°C until being detected at the same time with the other groups. Each mosquito was detected using real-time fluorescent RT-PCR kit. DENV-2 RNA concentration (copies/ml) and infection rate in each group were compared. Results Both of quantitatively and qualitatively inhibiting effects of ivermectin have been detected in this study. Generally, DENV-2 replicated well in Aedes albopictus without ivermectin intervention, whose virus loads exhibited significantly higher when the mosquitoes were holding from 4 days to 10 days after infectious blood feeding. In contrast, with the treatment of ivermectin, the infection rate was reduced by as much as 49.63%. The regression equation between infection rates (Y2) and ivermectin concentration log2 values (X2) was obtained as Y2 = 91.41–7.21*X2 with R2 = 0.89. Conclusion Ivermectin can directly or indirectly inhibit DENV-2 multiplication in Aedes albopictus. Moreover, the actual concentration for application in zooprophylaxis needs to be confirmed in the further field trials. Dengue fever is one of neglected vector-borne tropical diseases with a 30-fold increase in global incidence recently. In 2012, World Health Organization set a goal to reduce dengue mortality by at least 50% by 2020. Being faced with more challenges in the dengue control programs, such as the increase of dengue outbreaks, lacking absolutely effective vaccine, rise of vector insecticide resistance and so on; innovative vector control tools are urgently needed for current control programs on dengue fever. To find a new avenue in vector control, we for the first time assessed the inhibiting effectiveness of ivermectin on dengue virus type 2 (DENV-2) inside Aedes mosquitoes. We found that about 80% Aedes albopictus mosquitoes were effectively infected with DENV-2 without treatment of ivermectin. But in the groups of ivermectin treatment, the infection rate of DENV-2 and the median of virus loads were significantly reduced by up to 49.63% and 99.99%, respectively. Both quantitatively and qualitatively inhibiting effects of ivermectin were detected. We found out that ivermectin was able to effectively inhibit the DENV-2 multiplication in Aedes albopictus, which may gave us a hint that using ivermectin in some control programs as a zooprophylaxis to block dengue epidemic through inhibiting DENV-2 in field Aedes mosquitoes.
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Rabinovich NR. Ivermectin: repurposing an old drug to complement malaria vector control. THE LANCET. INFECTIOUS DISEASES 2018; 18:584-585. [PMID: 29602753 DOI: 10.1016/s1473-3099(18)30176-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Accepted: 03/02/2018] [Indexed: 11/18/2022]
Affiliation(s)
- N Regina Rabinovich
- Harvard T.H. Chan School of Public Health, Boston, MA 02115, USA; ISGlobal, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.
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Kobylinski KC, Escobedo-Vargas KS, López-Sifuentes VM, Durand S, Smith ES, Baldeviano GC, Gerbasi RV, Ballard SB, Stoops CA, Vásquez GM. Ivermectin susceptibility, sporontocidal effect, and inhibition of time to re-feed in the Amazonian malaria vector Anopheles darlingi. Malar J 2017; 16:474. [PMID: 29162101 PMCID: PMC5696779 DOI: 10.1186/s12936-017-2125-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/16/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Outdoor malaria transmission hinders malaria elimination efforts in the Amazon region and novel vector control tools are needed. Ivermectin mass drug administration (MDA) to humans kills wild Anopheles, targets outdoor-feeding vectors, and can suppress malaria parasite transmission. Laboratory investigations were performed to determine ivermectin susceptibility, sporontocidal effect and inhibition of time to re-feed for the primary Amazonian malaria vector, Anopheles darlingi. METHODS To assess ivermectin susceptibility, various concentrations of ivermectin were mixed in human blood and fed to An. darlingi. Mosquito survival was monitored daily for 7 days and a non-linear mixed effects model with Probit analysis was used to calculate lethal concentrations of ivermectin that killed 50% (LC50), 25% (LC25) and 5% (LC5) of mosquitoes. To examine ivermectin sporonticidal effect, Plasmodium vivax blood samples were collected from malaria patients and offered to mosquitoes without or with ivermectin at the LC50, LC25 or LC5. To assess ivermectin inhibition of mosquito time to re-feed, concentrations of ivermectin predicted to occur after a single oral dose of 200 μg/kg ivermectin were fed to An. darlingi. Every day for 12 days thereafter, individual mosquitoes were given the opportunity to re-feed on a volunteer. Any mosquitoes that re-blood fed or died were removed from the study. RESULTS Ivermectin significantly reduced An. darlingi survivorship: 7-day-LC50 = 43.2 ng/ml [37.5, 48.6], -LC25 = 27.8 ng/ml [20.4, 32.9] and -LC5 = 14.8 ng/ml [7.9, 20.2]. Ivermectin compound was sporontocidal to P. vivax in An. darlingi at the LC50 and LC25 concentrations reducing prevalence by 22.6 and 17.1%, respectively, but not at the LC5. Oocyst intensity was not altered at any concentration. Ivermectin significantly delayed time to re-feed at the 4-h (48.7 ng/ml) and 12-h (26.9 ng/ml) concentrations but not 36-h (10.6 ng/ml) or 60-h (6.3 ng/ml). CONCLUSIONS Ivermectin is lethal to An. darlingi, modestly inhibits sporogony of P. vivax, and delays time to re-feed at concentrations found in humans up to 12 h post drug ingestion. The LC50 value suggests that a higher than standard dose (400-μg/kg) is necessary to target An. darlingi. These results suggest that ivermectin MDA has potential in the Amazon region to aid malaria elimination efforts.
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Affiliation(s)
- Kevin C Kobylinski
- Department of Entomology, Armed Forces Research Institute of Medical Sciences, 315/6 Rajvithi Road, Bangkok, 10400, Thailand. .,Entomology Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA.
| | - Karín S Escobedo-Vargas
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Victor M López-Sifuentes
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Salomón Durand
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Edward S Smith
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - G Christian Baldeviano
- Department of Parasitology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Robert V Gerbasi
- Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, MD, 20910, USA
| | - Sara-Blythe Ballard
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe St., Rm. W5515, Baltimore, MD, 21205, USA
| | - Craig A Stoops
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
| | - Gissella M Vásquez
- Department of Entomology, U.S. Naval Medical Research Unit No. 6, Av. Venezuela block 36 s/n, Callao 2, Peru
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Lyimo IN, Kessy ST, Mbina KF, Daraja AA, Mnyone LL. Ivermectin-treated cattle reduces blood digestion, egg production and survival of a free-living population of Anopheles arabiensis under semi-field condition in south-eastern Tanzania. Malar J 2017; 16:239. [PMID: 28587669 PMCID: PMC5461717 DOI: 10.1186/s12936-017-1885-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 05/30/2017] [Indexed: 01/26/2023] Open
Abstract
Background Anopheles arabiensis feed on cattle and contributes to residual transmission of malaria in areas with high coverage of long-lasting insecticide-treated nets and indoor residual spraying in East Africa. This study aimed to evaluate the effects of ivermectin-treated cattle as a complementary vector control tool against population of An. arabiensis under the semi-field conditions in south-eastern Tanzania. Methods The free-living population of An. arabiensis was allowed to forage on untreated or ivermectin-treated cattle in alternating nights within the semi-field system in south-eastern Tanzania. Fresh blood fed mosquitoes were collected in the morning using mouth aspirators and assessed for their blood meal digestion, egg production, and survivorship. The residual activity of ivermectin-treated cattle was also determined by exposing mosquitoes to the same treatments after every 2 days until day 21 post-treatments. These experiments were replicated 3 times using different individual cattle. Results Overall, the ivermectin-treated cattle reduced blood meal digestion in the stomach of An. arabiensis, and their subsequent egg production and survival over time. The ivermectin-treated cattle halved blood meal digestion in mosquitoes, but reduced their egg production for up to 15 days. The ivermectin-treated cattle reduced the survival, and median survival times (1–3 days) of An. arabiensis than control cattle. The daily mortality rates of mosquitoes fed on ivermectin-treated cattle increased by five-fold relative to controls in the first week, and it gradually declined up to 21 days after treatment. Conclusion This study demonstrates that long-lasting effects of ivermectin-treated cattle on egg production and survival of An. arabiensis may sustainably suppress their vector density, and reduce residual transmission of malaria. This study suggests that ivermectin-treated non-lactating cattle (i.e. calves, heifers and bulls) could be suitable option for large-scale malaria vector control without limiting consumption of milk and meat by communities in rural settings. Furthermore, simulation models are underway to predict the impact of ivermectin-treated cattle alone, or in combination with LLIN/IRS, the frequency of treatment, and their coverage required to significantly suppress population of An. arabiensis and reduce residual transmission of malaria.
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Affiliation(s)
- Issa N Lyimo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O.BOX 53, Ifakara, Morogoro, United Republic of Tanzania.
| | - Stella T Kessy
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O.BOX 53, Ifakara, Morogoro, United Republic of Tanzania
| | - Kasian F Mbina
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O.BOX 53, Ifakara, Morogoro, United Republic of Tanzania
| | - Ally A Daraja
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O.BOX 53, Ifakara, Morogoro, United Republic of Tanzania
| | - Ladslaus L Mnyone
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, P.O.BOX 53, Ifakara, Morogoro, United Republic of Tanzania.,Pest Management Centre, Sokoine University of Agriculture, Morogoro, Tanzania.,School of Public Health, University of the Witwatersrand, Parktown, Republic of South Africa
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Kositz C, Talina J, Diau J, Asugeni R, Whitehorn C, Mabey D, Chaccour C, Marks M. Incidental mosquitocidal effect of an ivermectin mass drug administration on Anopheles farauti conducted for scabies control in the Solomon Islands. Trans R Soc Trop Med Hyg 2017; 111:97-101. [PMID: 28549173 PMCID: PMC5722049 DOI: 10.1093/trstmh/trx025] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Revised: 05/02/2017] [Accepted: 05/11/2017] [Indexed: 11/09/2022] Open
Abstract
Background The Solomon Islands is targeting elimination of malaria by 2030. The dominant vector is the predominantly exophagic, exophilic Anopheles farauti sensu strictu. This biting behaviour limits the efficacy of conventional vector control tools and highlights the need for new strategies. When administered to humans ivermectin has been shown to have a mosquitocidal effect. Mass drug administration (MDA) with ivermectin is an emerging strategy in the control of scabies. In this study we explored any incidental effect of ivermectin MDA conducted for scabies control on mosquitoes. Methods MDA for scabies was conducted in three villages. We performed human landing catches and measured 5-day mortality amongst Anopheles mosquitoes caught before and after MDA. Cox regression was used to calculate hazard ratios (HR) for mortality between mosquitoes caught before and after MDA. Results There was a significant increase in 5-day mortality in anopheline mosquitoes caught post-MDA which was highest on the day of MDA itself (HR 4.2 95% CI 1.8 to 10.1, p=0.001) and the following day (HR 4.4 95% CI 1.8 to 10.8, p=0.002) compared to mosquitoes caught before MDA. Conclusions This study shows a possible mosquitocidal effect of ivermectin MDA conducted for scabies control. Studies with a larger sample size with clinical as well as entomological outcomes should be conducted in this population.
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Affiliation(s)
- Christian Kositz
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - Jeptah Talina
- Atoifi Adventist Hospital, Atoifi, Malaita, Solomon Islands
| | - Jason Diau
- Atoifi Adventist Hospital, Atoifi, Malaita, Solomon Islands
| | - Rowena Asugeni
- Atoifi Adventist Hospital, Atoifi, Malaita, Solomon Islands
| | - Cheryl Whitehorn
- Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
| | - David Mabey
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Hospital for Tropical Diseases, University College London Hospitals NHS Trust, London, UK
| | - Carlos Chaccour
- ISGlobal, Barcelona Centre for International Health Research (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain
| | - Michael Marks
- Clinical Research Department, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK
- Hospital for Tropical Diseases, University College London Hospitals NHS Trust, London, UK
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23
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Alout H, Foy BD. Ivermectin: a complimentary weapon against the spread of malaria? Expert Rev Anti Infect Ther 2016; 15:231-240. [PMID: 27960597 DOI: 10.1080/14787210.2017.1271713] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Ivermectin has transformed the treatment of parasitic diseases and led to incommensurable benefits to humans and animals. Ivermectin is effective in treating several neglected infectious diseases and recently it has been shown to reduce malaria parasite transmission. Areas covered: Malaria control strategies could benefit from the addition of ivermectin to interrupt the transmission cycle if it is a long lasting formulation or repeatedly administered. In turn, this will help also to control neglected infectious diseases where the elimination goal has been slower to achieve. Despite the relevance of using ivermectin for integrated and sustained disease control, there are still essential questions that remain to be addressed about safety and practicality. The efficacy in various malaria ecologies and the interaction between control tools, either drugs or insecticides, are also important to assess. Expert commentary: Overlapping distribution of several infectious diseases reveals the benefit of integrating control programs against several infectious diseases into one strategy for cost effectiveness and to reach the elimination goals. The use of ivermectin to control malaria transmission will necessitate development and testing of long-lasting formulations or repeated treatments, and implementation of these treatments with other disease control tools may increase the chance of successful and sustained control.
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Affiliation(s)
- Haoues Alout
- a Microbiology, Immunology and Pathology & Arthropod-borne Infectious Diseases Laboratory , Colorado State University , Fort Collins , CO , USA
| | - Brian D Foy
- a Microbiology, Immunology and Pathology & Arthropod-borne Infectious Diseases Laboratory , Colorado State University , Fort Collins , CO , USA
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Irish SR, Stevens WMB, Derua YA, Walker T, Cameron MM. Comparison of Methods for Xenomonitoring in Vectors of Lymphatic Filariasis in Northeastern Tanzania. Am J Trop Med Hyg 2015; 93:983-9. [PMID: 26350454 PMCID: PMC4703286 DOI: 10.4269/ajtmh.15-0234] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 07/14/2015] [Indexed: 11/07/2022] Open
Abstract
Monitoring Wuchereria bancrofti infection in mosquitoes (xenomonitoring) can play an important role in determining when lymphatic filariasis has been eliminated, or in focusing control efforts. As mosquito infection rates can be low, a method for collecting large numbers of mosquitoes is necessary. Gravid traps collected large numbers of Culex quinquefasciatus in Tanzania, and a collection method that targets mosquitoes that have already fed could result in increased sensitivity in detecting W. bancrofti-infected mosquitoes. The aim of this experiment was to test this hypothesis by comparing U.S. Centers for Disease Control and Prevention (CDC) light traps with CDC gravid traps in northeastern Tanzania, where Cx. quinquefasciatus is a vector of lymphatic filariasis. After an initial study where small numbers of mosquitoes were collected, a second study collected 16,316 Cx. quinquefasciatus in 60 gravid trap-nights and 240 light trap-nights. Mosquitoes were pooled and tested for presence of W. bancrofti DNA. Light and gravid traps collected similar numbers of mosquitoes per trap-night, but the physiological status of the mosquitoes was different. The estimated infection rate in mosquitoes collected in light traps was considerably higher than in mosquitoes collected in gravid traps, so light traps can be a useful tool for xenomonitoring work in Tanzania.
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Affiliation(s)
- Seth R Irish
- London School of Hygiene and Tropical Medicine, London, United Kingdom; National Institute for Medical Research, Muheza, Tanzania
| | - William M B Stevens
- London School of Hygiene and Tropical Medicine, London, United Kingdom; National Institute for Medical Research, Muheza, Tanzania
| | - Yahya A Derua
- London School of Hygiene and Tropical Medicine, London, United Kingdom; National Institute for Medical Research, Muheza, Tanzania
| | - Thomas Walker
- London School of Hygiene and Tropical Medicine, London, United Kingdom; National Institute for Medical Research, Muheza, Tanzania
| | - Mary M Cameron
- London School of Hygiene and Tropical Medicine, London, United Kingdom; National Institute for Medical Research, Muheza, Tanzania
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Seaman JA, Alout H, Meyers JI, Stenglein MD, Dabiré RK, Lozano-Fuentes S, Burton TA, Kuklinski WS, Black WC, Foy BD. Age and prior blood feeding of Anopheles gambiae influences their susceptibility and gene expression patterns to ivermectin-containing blood meals. BMC Genomics 2015; 16:797. [PMID: 26471037 PMCID: PMC4608139 DOI: 10.1186/s12864-015-2029-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/08/2015] [Indexed: 02/04/2023] Open
Abstract
Background Ivermectin has been proposed as a novel malaria transmission control tool based on its insecticidal properties and unique route of acquisition through human blood. To maximize ivermectin’s effect and identify potential resistance/tolerance mechanisms, it is important to understand its effect on mosquito physiology and potential to shift mosquito population age-structure. We therefore investigated ivermectin susceptibility and gene expression changes in several age groups of female Anopheles gambiae mosquitoes. Methods The effect of aging on ivermectin susceptibility was analyzed in three age groups (2, 6, and 14-days) of colonized female Anopheles gambiae mosquitoes using standard survivorship assays. Gene expression patterns were then analyzed by transcriptome sequencing on an Illumina HiSeq 2500 platform. RT-qPCR was used to validate transcriptional changes and also to examine expression in a different, colonized strain and in wild mosquitoes, both of which blood fed naturally on an ivermectin-treated person. Results Mosquitoes of different ages and blood meal history died at different frequencies after ingesting ivermectin. Mortality was lowest in 2-day old mosquitoes exposed on their first blood meal and highest in 6-day old mosquitoes exposed on their second blood meal. Twenty-four hours following ivermectin ingestion, 101 and 187 genes were differentially-expressed relative to control blood-fed, in 2 and 6-day groups, respectively. Transcription patterns of select genes were similar in membrane-fed, colonized, and naturally-fed wild vectors. Transcripts from several unexpected functional classes were highly up-regulated, including Niemann-Pick Type C (NPC) genes, peritrophic matrix-associated genes, and immune-response genes, and these exhibited different transcription patterns between age groups, which may explain the observed susceptibility differences. Niemann-Pick Type 2 genes were the most highly up-regulated transcripts after ivermectin ingestion (up to 160 fold) and comparing phylogeny to transcriptional patterns revealed that NPCs have rapidly evolved and separate members respond to either blood meals or to ivermectin. Conclusion We present evidence of increased ivermectin susceptibility in older An. gambiae mosquitoes that had previously bloodfed. Differential expression analysis suggests complex midgut interactions resulting from ivermectin ingestion that likely involve blood meal digestion physiological responses, midgut microflora, and innate immune responses. Thus, the transcription of certain gene families is consistently affected by ivermectin ingestion, and may provide important clues to ivermectin’s broad effects on malaria vectors. These findings contribute to the growing understanding of ivermectin’s potential as a transmission control tool. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2029-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jonathan A Seaman
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Haoues Alout
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Jacob I Meyers
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Mark D Stenglein
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Roch K Dabiré
- Institute de Recherche en Sciences de la Santé (IRSS)/Centre Muraz, Direction Régionale de l'Ouest, 399 Ave de la Liberté, Bobo Dioulasso, Houet, 10400-000, Burkina Faso.
| | - Saul Lozano-Fuentes
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Timothy A Burton
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Wojtek S Kuklinski
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
| | - Brian D Foy
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University 1692 Campus Delivery, Fort Collins, CO, 80525, USA.
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Poché RM, Burruss D, Polyakova L, Poché DM, Garlapati RB. Treatment of livestock with systemic insecticides for control of Anopheles arabiensis in western Kenya. Malar J 2015; 14:351. [PMID: 26377691 PMCID: PMC4574316 DOI: 10.1186/s12936-015-0883-0] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 09/03/2015] [Indexed: 12/01/2022] Open
Abstract
Background Despite the implementation of vector control strategies, including insecticide-treated bed nets (ITN) and indoor residual spraying (IRS) in western Kenya, this area still experiences high level of malaria transmission. Novel vector control tools are required which target such vector species, such as Anopheles arabiensis, that feed outdoors and have minimal contact with ITNs and IRS. Methods To address this need, ivermectin, eprinomectin, and fipronil were evaluated in Zebu cattle under semi-field conditions to evaluate the potential of these compounds to reduce the survival of blood feeding An. arabiensis. Over the course of four experiments, lactating cattle received doses of oral ivermectin at 0.1 or 0.2 mg/kg, oral eprinomectin at 0.2 or 0.5 mg/kg, topical eprinomectin at 0.5, 0.75, or 1.5 mg/kg, or oral fipronil at 0.25, 0.5, 1.0, or 1.5 mg/kg. On days 1, 3, 5, 7, 14, and 21 days post-treatment, cattle were exposed to An. arabiensis, and mosquito mortality post-blood feeding was monitored. For the analysis of survival data, the Kaplan–Meier estimator and Mantel–Haenszel test was used to contrast the treatment and control survival functions. Results All three compounds significantly reduced the survival time of An. arabiensis. Twenty-one days post-treatment, mortality of mosquitoes fed on cattle dosed orally with 0.2 or 0.5 mg/kg eprinomectin, topically with eprinomectin at 0.5 mg/kg, or orally with either 1.0 or 1.5 mg/kg fipronil was still significantly higher than control mortality. Conclusions These data demonstrate the effectiveness of three insecticidal compounds administered systemically to cattle for controlling the cattle-feeding mosquito An. arabiensis. Eprinomectin and fipronil provided the longest-lasting control. Such endectocidal treatments in cattle are a promising new strategy for control of residual, outdoor malaria transmission and could effectively augment current interventions which target more endophilic vector species. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0883-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Richard M Poché
- Genesis Laboratories, P.O. Box 1195, Wellington, CO, 80549, USA.
| | - Dylan Burruss
- Genesis Laboratories, P.O. Box 1195, Wellington, CO, 80549, USA.
| | - Larisa Polyakova
- Genesis Laboratories, P.O. Box 1195, Wellington, CO, 80549, USA.
| | - David M Poché
- Genesis Laboratories, P.O. Box 1195, Wellington, CO, 80549, USA.
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Alout H, Krajacich BJ, Meyers JI, Grubaugh ND, Brackney DE, Kobylinski KC, Diclaro JW, Bolay FK, Fakoli LS, Diabaté A, Dabiré RK, Bougma RW, Foy BD. Evaluation of ivermectin mass drug administration for malaria transmission control across different West African environments. Malar J 2014; 13:417. [PMID: 25363349 PMCID: PMC4226880 DOI: 10.1186/1475-2875-13-417] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Accepted: 10/25/2014] [Indexed: 11/06/2022] Open
Abstract
Background Mass drug administration (MDA) of ivermectin to humans for control and elimination of filarial parasites can kill biting malaria vectors and lead to Plasmodium transmission reduction. This study examines the degree and duration of mosquitocidal effects resulting from single MDAs conducted in three different West African countries, and the subsequent reductions in parity and Plasmodium sporozoite rates. Methods Indoor-resting, blood-fed and outdoor host-seeking Anopheles spp. were captured on days surrounding MDAs from 2008–2013 in Senegalese, Liberian and Burkinabé villages. Mortality was assessed on a portion of the indoor collection, and parity status was determined on host-seeking mosquitoes. The effect of MDA was then analysed against the time relative to the MDA, the distributed drugs and environmental variables. Results Anopheles gambiae survivorship was reduced by 33.9% for one week following MDA and parity rates were significantly reduced for more than two weeks after the MDAs. Sporozoite rates were significantly reduced by >77% for two weeks following the MDAs in treatment villages despite occurring in the middle of intense transmission seasons. These observed effects were consistent across three different West African transmission dynamics. Conclusions These data provide a comprehensive and crucial evidence base for the significant reduction in malaria transmission following single ivermectin MDAs across diverse field sites. Despite the limited duration of transmission reduction, these results support the hypothesis that repeated MDAs with optimal timing could help sustainably control malaria as well as filarial transmission. Electronic supplementary material The online version of this article (doi:10.1186/1475-2875-13-417) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Haoues Alout
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA.
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Slater HC, Walker PGT, Bousema T, Okell LC, Ghani AC. The potential impact of adding ivermectin to a mass treatment intervention to reduce malaria transmission: a modelling study. J Infect Dis 2014; 210:1972-80. [PMID: 24951826 DOI: 10.1093/infdis/jiu351] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Ivermectin (IVM), used alongside mass treatment strategies with an artemisinin combination therapy, has been suggested as a possible tool for reducing malaria transmission. Mosquitoes ingesting a bloodmeal containing IVM have increased mortality, reducing the probability that the parasite completes sporogony. METHODS Human pharmacokinetic data and mortality data for mosquitoes taking bloodmeals containing IVM are used to quantify the mosquitocidal effect of IVM. These are incorporated into a transmission model to estimate the impact of IVM in combination with mass treatment strategies with artemether-lumefantrine on transmission metrics. RESULTS Adding IVM increases the reductions in parasite prevalence achieved and delays the reemergence of parasites compared to mass treatment alone. This transmission effect is obtained through its effect on vector mortality. IVM effectiveness depends on coverage with the highest impact achieved if given to the whole population rather than only those with existing detectable parasites. Our results suggest that including IVM in a mass treatment strategy can reduce the time taken to interrupt transmission as well as help to achieve transmission interruption in transmission settings in which mass treatment strategies alone would be insufficient. CONCLUSIONS Including IVM in mass treatment strategies could be a useful adjunct to reduce and interrupt malaria transmission.
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Affiliation(s)
- Hannah C Slater
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, United Kingdom
| | - Patrick G T Walker
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, United Kingdom
| | - Teun Bousema
- Department of Medical Microbiology, Radboud University Medical Center, Nijmegen, Netherlands Department of Immunology and Infection, London School of Hygiene and Tropical Medicine, United Kingdom
| | - Lucy C Okell
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, United Kingdom
| | - Azra C Ghani
- MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, United Kingdom
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Chaccour CJ, Kobylinski KC, Bassat Q, Bousema T, Drakeley C, Alonso P, Foy BD. Ivermectin to reduce malaria transmission: a research agenda for a promising new tool for elimination. Malar J 2013; 12:153. [PMID: 23647969 PMCID: PMC3658945 DOI: 10.1186/1475-2875-12-153] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Accepted: 05/01/2013] [Indexed: 11/11/2022] Open
Abstract
Background The heterogeneity of malaria transmission makes widespread elimination a difficult goal to achieve. Most of the current vector control measures insufficiently target outdoor transmission. Also, insecticide resistance threatens to diminish the efficacy of the most prevalent measures, indoor residual spray and insecticide treated nets. Innovative approaches are needed. The use of endectocides, such as ivermectin, could be an important new addition to the toolbox of anti-malarial measures. Ivermectin effectively targets outdoor transmission, has a novel mechanism of action that could circumvent resistance and might be distributed over the channels already in place for the control of onchocerciasis and lymphatic filariasis. Methods The previous works involving ivermectin and Anopheles vectors are reviewed and summarized. A review of ivermectin’s safety profile is also provided. Finally three definitive clinical trials are described in detail and proposed as the evidence needed for implementation. Several smaller and specific supportive studies are also proposed. Conclusions The use of ivermectin solves many challenges identified for future vector control strategies. It is an effective and safe endectocide that was approved for human use more than 25 years ago. Recent studies suggest it might become an effective and complementary strategy in malaria elimination and eradication efforts; however, intensive research will be needed to make this a reality.
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Affiliation(s)
- Carlos J Chaccour
- Internal Medicine Department, Clínica Universidad de Navarra, Av, Pio XII 36, Pamplona 31008, Spain.
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Kobylinski KC, Foy BD, Richardson JH. Ivermectin inhibits the sporogony of Plasmodium falciparum in Anopheles gambiae. Malar J 2012; 11:381. [PMID: 23171202 PMCID: PMC3519548 DOI: 10.1186/1475-2875-11-381] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 11/17/2012] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND When ingested in a blood meal, ivermectin has been shown to reduce the survivorship of Anopheles gambiae in the laboratory and field. Furthermore, ivermectin mass drug administrations in Senegal have been shown to reduce the proportion of Plasmodium falciparum-sporozoite-containing An. gambiae. This study addresses whether ivermectin inhibits sporogony of P. falciparum in An. gambiae. METHODS Anophele gambiae s.s. G3 strain were fed two concentrations of ivermectin (LC25 and LC5) along with P. falciparum NF54 in human blood meals at staggered intervals. Mosquitoes ingested ivermectin concurrent with parasites (DPI 0), or at three (DPI 3), six (DPI 6), and nine (DPI 9) days post parasite ingestion, or three days prior (DPI -3) to parasite ingestion. Mosquitoes were dissected at seven, twelve or fourteen days post parasite ingestion and either oocyst or sporozoite prevalence was recorded. To determine if P. falciparum sporozoite-containing An. gambiae were more susceptible to ivermectin than uninfected controls, survivorship was recorded for mosquitoes which ingested P. falciparum or control blood meal on DPI 0 and then a second blood meal containing ivermectin (LC25) on DPI 14. RESULTS Ivermectin (LC25) co-ingested (DPI 0) with parasites reduced the proportion of An. gambiae that developed oocysts (χ2 = 15.4842, P = 0.0002) and sporozoites (χ2 = 19.9643, P < 0.0001). Ivermectin (LC25) ingested DPI 6 (χ2 = 8.5103, P = 0.0044) and 9 (χ2 = 14.7998, P < 0.0001) reduced the proportion of An. gambiae that developed sporozoites but not when ingested DPI 3 (χ2 = 0.0113, P = 1). Ivermectin (LC5) co-ingested (DPI 0) with parasites did not reduce the proportion of An. gambiae that developed oocysts (χ2 = 4.2518, P = 0.0577) or sporozoites (χ2 = 2.3636, P = 0.1540), however, when ingested DPI -3 the proportion of An. gambiae that developed sporozoites was reduced (χ2 = 8.4806, P = 0.0047). Plasmodium falciparum infection significantly reduced the survivorship of An. gambiae that ingested ivermectin (LC25) on DPI 14 compared to control mosquitoes that ingested a primary blood meal without parasites (χ2 = 4.97, P = 0.0257). CONCLUSIONS Ivermectin at sub-lethal concentrations inhibits the sporogony of P. falciparum in An. gambiae. These findings support the utility of ivermectin for P. falciparum transmission control.
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Affiliation(s)
- Kevin C Kobylinski
- Entomology Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
| | - Brian D Foy
- Department of Microbiology, Immunology and Pathology, Arthropod-borne and Infectious Diseases Laboratory, Colorado State University, 1692 Campus Delivery, Fort Collins, CO, 80523-1692, USA
| | - Jason H Richardson
- Entomology Branch, Walter Reed Army Institute of Research, 503 Robert Grant Ave, Silver Spring, MD, 20910, USA
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van den Berg H, Kelly-Hope LA, Lindsay SW. Malaria and lymphatic filariasis: the case for integrated vector management. THE LANCET. INFECTIOUS DISEASES 2012; 13:89-94. [PMID: 23084831 DOI: 10.1016/s1473-3099(12)70148-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The global programmes to eliminate both malaria and lymphatic filariasis are facing operational and technical challenges. Available data show that the use of treated or untreated bednets and indoor residual spraying for malaria control concomitantly reduced filarial rates. In turn, mass drug administration campaigns against lymphatic filariasis can be combined with the distribution of insecticide-treated bednets. Combining these disease control efforts could lead to more efficient use of resources, more accurate attribution of effects, and more effective control of both diseases. Systematic integration requires coordination at all levels, mapping of coendemic areas, and comprehensive monitoring and evaluation.
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Affiliation(s)
- Henk van den Berg
- Laboratory of Entomology, Wageningen University, Wageningen, Netherlands.
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Deus KM, Saavedra-Rodriguez K, Butters MP, Black WC, Foy BD. The effect of ivermectin in seven strains of Aedes aegypti (Diptera: Culicidae) including a genetically diverse laboratory strain and three permethrin resistant strains. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:356-63. [PMID: 22493855 PMCID: PMC3942497 DOI: 10.1603/me11164] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all strains. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among strains, and all three permethrin-resistant strains were significantly less susceptible to ivermectin than the standard reference strain. The hatch rate after an ivermectin bloodmeal was less variable among strains, and only one of the permethrin-resistant strains differed significantly from the standard reference strain. Our studies suggest that ivermectin induces adult mortality and decreases the hatch rate of eggs through different mechanisms. A correlation analysis of log-transformed LC50 among strains suggests that permethrin and ivermectin cross-resistance may occur.
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Affiliation(s)
- K M Deus
- Colorado State University, Department of Microbiology, Immunology and Pathology, 1692 Campus Delivery, Fort Collins, CO 80523, USA.
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Fritz ML, Walker ED, Miller JR. Lethal and sublethal effects of avermectin/milbemycin parasiticides on the African malaria vector, Anopheles arabiensis. JOURNAL OF MEDICAL ENTOMOLOGY 2012; 49:326-331. [PMID: 22493850 DOI: 10.1603/me11098] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Four cattle parasiticides of the avermectin/milbemycin class were examined for lethal and sublethal effects on the zoophilic, African malaria vector Anopheles arabiensis. Ivermectin, moxidectin, doramectin, and eprinomectin were mixed with bovine blood and provided to laboratory-reared An. arabiensis in a membrane feeder. Ivermectin and eprinomectin were lethal to An. arabiensis at low concentrations (LC50s of 7.9 ppb and 8.5 ppb, respectively). While the lethality of doramectin (LC50 of 23.9 ppb), was less than that of ivermectin and eprinomectin, it markedly reduced egg development. The concentration of moxidectin required to reduce survivorship and egg production in An. arabiensis was > 100 fold greater than for ivermectin or eprinomectin. Moxidectin was weak in its actions against An. arabiensis relative to the other three chemicals. These results suggest that cattle treated with ivermectin or eprinomectin in the prescribed range of low dosages as parasiticides have blood toxic to zoophilic malaria vectors. Regionally coordinated, seasonal treatment of cattle could suppress An. arabiensis populations, thereby reducing malaria transmission. Doramectin (although less toxic) would have population level effects on egg production if used in this manner.
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Affiliation(s)
- Megan L Fritz
- Department of Entomology, Michigan State University, 203 Center for Integrated Plant Systems, East Lansing, MI, 48824, USA
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Butters MP, Kobylinski KC, Deus KM, da Silva IM, Gray M, Sylla M, Foy BD. Comparative evaluation of systemic drugs for their effects against Anopheles gambiae. Acta Trop 2012; 121:34-43. [PMID: 22019935 DOI: 10.1016/j.actatropica.2011.10.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Revised: 10/06/2011] [Accepted: 10/07/2011] [Indexed: 12/11/2022]
Abstract
Laboratory and field studies have shown that ivermectin, a drug that targets invertebrate ligand-gated ion channels (LGICs), is potently active against Anopheles spp. mosquitoes at concentrations present in human blood after standard drug administrations; thus ivermectin holds promise as a mass human-administered endectocide that could help suppress malaria parasite transmission. We evaluated other systemic LGIC-targeting drugs for their activities against the African malaria vector Anopheles gambiae using in vitro blood feeding assays. Eprinomectin, selamectin, moxidectin, and N-tert-butyl nodulisporamide were evaluated as potentially systemic drugs having similar modes of action to ivermectin; all primarily are agonists of invertebrate glutamate-gated chloride ion channels. Additionally, nitenpyram and spinosad were evaluated as systemic drugs that primarily work as agonists of nicotinic acetylcholine receptor channels. Only eprinomectin killed An. gambiae at concentrations that were comparable to ivermectin. At sub-lethal doses, nitenpyram and moxidectin marginally affected mosquito re-blood feeding ability. The macrocyclic lactones, particularly eprinomectin, caused significantly increased knockdown and significantly inhibited recovery in blood fed females. These data are a first step in evaluating drugs that might be eventually combined with, or substituted for ivermectin for future malaria parasite transmission control.
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Foy BD, Kobylinski KC, da Silva IM, Rasgon JL, Sylla M. Endectocides for malaria control. Trends Parasitol 2011; 27:423-8. [PMID: 21727027 DOI: 10.1016/j.pt.2011.05.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 05/27/2011] [Accepted: 05/31/2011] [Indexed: 02/03/2023]
Abstract
Systemic endectocidal drugs, used to control nematodes in humans and other vertebrates, can be toxic to Anopheles spp. mosquitoes when they take a blood meal from a host that has recently received one of these drugs. Recent laboratory and field studies have highlighted the potential of ivermectin to control malaria parasite transmission if this drug is distributed strategically and more often. There are important theoretical benefits to this strategy, as well as caveats. A better understanding of drug effects against vectors and malaria ecologies are needed. In the near future, ivermectin and other endectocides could serve as potent and novel malaria transmission control tools that are directly linked to the control of neglected tropical diseases in the same communities.
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Affiliation(s)
- Brian D Foy
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1692, USA.
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Allan SA. Susceptibility of adult mosquitoes to insecticides in aqueous sucrose baits. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2011; 36:59-67. [PMID: 21635642 DOI: 10.1111/j.1948-7134.2011.00141.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Mosquitoes characteristically feed on plant-derived carbohydrates and honeydew just after emergence and intermittently during their lives. Development of toxic baits focusing on this carbohydrate-seeking behavior may potentially contribute to localized control. In the present study, ten insecticides were fed to female Culex quinquefasciatus, Anopheles quadrimaculatus, and Aedes taeniorhynchus in a 10% sucrose solution. Active ingredients representative of five classes of insecticides (pyrethroids, phenylpyroles, pyrroles, neonicotinoids, and macrocyclic lactones) were selected for comparison with commercial formulations used to facilitate incorporation of active ingredients into aqueous sucrose solutions. Sucrose as a phagostimulant significantly enhanced mortality to toxicants. In general, the most effective active ingredients were fipronil, deltamethrin and imidacloprid, followed by spinosad, thiamethoxam, bifenthrin, permethrin, and cyfluthrin. The least effective ingredients were chlorfenapyr and ivermectin. For some of the ingredients tested, Cx. quinquefasciatus was the least susceptible species. One-day-old male Cx. quinquefasciatus were more susceptible than females; however, no differences existed between one- and seven-day-old mosquitoes. There were no differences in susceptibility between unfed and gravid ten-day-old female Cx. quinquefasciatus to bifenthrin. In conclusion, several pesticides from different classes of compounds have potential for use in development of toxic baits for mosquitoes.
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Affiliation(s)
- Sandra A Allan
- Center for Medical, Agricultural and Veterinary Entomology, USDA/ARS, 1600 SW 23rd Dr., Gainesville, FL 32608, USA
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Hanafi HA, Szumlas DE, Fryauff DJ, El-Hossary SS, Singer GA, Osman SG, Watany N, Furman BD, Hoel DF. Effects of Ivermectin on Blood-Feeding Phlebotomus papatasi, and the Promastigote Stage of Leishmania major. Vector Borne Zoonotic Dis 2011; 11:43-52. [DOI: 10.1089/vbz.2009.0030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Hanafi A. Hanafi
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - Daniel E. Szumlas
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - David J. Fryauff
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - Shabaan S. El-Hossary
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - Gamal A. Singer
- Department of Chemistry, Faculty of Science, Helwan University, Helwan, Egypt
| | - Samir G. Osman
- Department of Research and Development, Egyptian Company for Chemicals and Pharmaceuticals (ADWIA), Cairo, Egypt
| | - Noha Watany
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - Barry D. Furman
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
| | - David F. Hoel
- Vector Biology Research Program, U.S. Naval Medical Research Unit No. 3, Cairo, Egypt
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Sylla M, Kobylinski KC, Gray M, Chapman PL, Sarr MD, Rasgon JL, Foy BD. Mass drug administration of ivermectin in south-eastern Senegal reduces the survivorship of wild-caught, blood fed malaria vectors. Malar J 2010; 9:365. [PMID: 21171970 PMCID: PMC3016374 DOI: 10.1186/1475-2875-9-365] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2010] [Accepted: 12/20/2010] [Indexed: 11/25/2022] Open
Abstract
Background In south-eastern Senegal, malaria and onchocerciasis are co-endemic. Onchocerciasis in this region has been controlled by once or twice yearly mass drug administration (MDA) with ivermectin (IVM) for over fifteen years. Since laboratory-raised Anopheles gambiae s.s. are susceptible to ivermectin at concentrations found in human blood post-ingestion of IVM, it is plausible that a similar effect could be quantified in the field, and that IVM might have benefits as a malaria control tool. Methods In 2008 and 2009, wild-caught blood fed An. gambiae s.l. mosquitoes were collected from huts of three pairs of Senegalese villages before and after IVM MDAs. Mosquitoes were held in an insectary to assess their survival rate, subsequently identified to species, and their blood meals were identified. Differences in mosquito survival were statistically analysed using a Glimmix model. Lastly, changes in the daily probability of mosquito survivorship surrounding IVM MDAs were calculated, and these data were inserted into a previously developed, mosquito age-structured model of malaria transmission. Results Anopheles gambiae s.s. (P < 0.0001) and Anopheles arabiensis (P = 0.0191) from the treated villages had significantly reduced survival compared to those from control villages. Furthermore, An gambiae s.s. caught 1-6 days after MDA in treated villages had significantly reduced survival compared to control village collections (P = 0.0003), as well as those caught pre-MDA (P < 0.0001) and >7 days post-MDA (P < 0.0001). The daily probability of mosquito survival dropped >10% for the six days following MDA. The mosquito age-structured model of malaria transmission demonstrated that a single IVM MDA would reduce malaria transmission (Ro) below baseline for at least eleven days, and that repeated IVM MDAs would result in a sustained reduction in malaria Ro. Conclusions Ivermectin MDA significantly reduced the survivorship of An. gambiae s.s. for six days past the date of the MDA, which is sufficient to temporarily reduce malaria transmission. Repeated IVM MDAs could be a novel and integrative malaria control tool in areas with seasonal transmission, and which would have simultaneous impacts on neglected tropical diseases in the same villages.
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Affiliation(s)
- Massamba Sylla
- Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, USA.
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Kobylinski KC, Deus KM, Butters MT, Hongyu T, Gray M, Silva IMD, Sylla M, Foy BD. The effect of oral anthelmintics on the survivorship and re-feeding frequency of anthropophilic mosquito disease vectors. Acta Trop 2010; 116:119-26. [PMID: 20540931 PMCID: PMC2939250 DOI: 10.1016/j.actatropica.2010.06.001] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 05/29/2010] [Accepted: 06/01/2010] [Indexed: 11/16/2022]
Abstract
In the Tropics, there is substantial temporal and spatial overlap of diseases propagated by anthropophilic mosquito vectors (such as malaria and dengue) and human helminth diseases (such as onchocerciasis and lymphatic filariasis) that are treated though mass drug administrations (MDA). This overlap will result in mosquito vectors imbibing significant quantities of these drugs when they blood feed on humans. Since many anthelmintic drugs have broad anti-invertebrate effects, the possibility of combined helminth control and mosquito-borne disease control through MDA is apparent. It has been previously shown that ivermectin can reduce mosquito survivorship when administered in a blood meal, but more detailed examinations are needed if MDA is to ever be developed into a tool for malaria or dengue control. We examined concentrations of drugs that follow human pharmacokinetics after MDA and that matched with mosquito feeding times, for effects against the anthropophilic mosquito vectors Anopheles gambiae s.s. and Aedes aegypti. Ivermectin was the only human-approved MDA drug we tested that affected mosquito survivorship, and only An. gambiae s.s. were affected at concentrations respecting human pharmacokinetics at indicated doses. Ivermectin also delayed An. gambiae s.s. re-feeding frequency and defecation rates, and two successive ivermectin-spiked blood meals following human pharmacokinetic concentrations compounded mortality effects compared to controls. These findings suggest that ivermectin MDA in Africa may be used to decrease malaria transmission if MDAs were administered more frequently. Such a strategy would broaden the current scope of polyparasitism control already afforded by MDAs, and which is needed in many African villages simultaneously burdened by many parasitic diseases.
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Affiliation(s)
- Kevin C. Kobylinski
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kelsey M. Deus
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Matt T. Butters
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Tan Hongyu
- Department of Statistics, Colorado State University, Fort Collins, Colorado, United States of America
| | - Meg Gray
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ines Marques da Silva
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Massamba Sylla
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Brian D. Foy
- Arthropod-borne & Infectious Diseases Laboratory, Department of Microbiology, Immunology & Pathology, Colorado State University, Fort Collins, Colorado, United States of America
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Mascari T, Foil L. Oral treatment of rodents with ivermectin for the control of Phlebotomus papatasi (Diptera: Psychodidae) under laboratory conditions. Vet Parasitol 2010; 171:130-5. [DOI: 10.1016/j.vetpar.2010.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 03/04/2010] [Accepted: 03/09/2010] [Indexed: 11/26/2022]
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Fritz ML, Siegert PY, Walker ED, Bayoh MN, Vulule JR, Miller JR. Toxicity of bloodmeals from ivermectin-treated cattle to Anopheles gambiae s.l. ANNALS OF TROPICAL MEDICINE AND PARASITOLOGY 2010; 103:539-47. [PMID: 19695159 DOI: 10.1179/000349809x12459740922138] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Two anthelmintic drugs used as cattle dewormers, ivermectin and moxidectin, were tested for their lethal and sublethal effects on the malarial vectors Anopheles gambiae s.s. and An. arabiensis. In the laboratory, direct addition of ivermectin to bovine blood reduced the survivorship and fecundity of mosquitoes fed on the blood. The median lethal concentration (LC(50)) of ivermectin in the bloodmeal, for the laboratory populations of An. gambiae s.l., was 19.8 ppb. In the field, commercially available formulations containing ivermectin or moxidectin were injected into cattle at three times the recommended dose. Most (90%) of the An. gambiae s.s. that fed on the ivermectin-treated cattle within 2 weeks of treatment failed to survive more than 10 days post-bloodmeal. No eggs were deposited by An. gambiae s.s. that fed on ivermectin-treated cattle within 10 days of treatment. In contrast, the survivorship and egg production of the mosquitoes that fed on the moxidectin-treated cattle were no different from those feeding on untreated cattle. These results indicate that treatment of cattle with ivermectin could be used, as part of an integrated control programme, to reduce the zoophilic vector populations that contribute to the transmission of the parasites responsible for human malaria.
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Affiliation(s)
- M L Fritz
- Department of Entomology, Michigan State University, East Lansing, MI 48824, USA
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Are coinfections of malaria and filariasis of any epidemiological significance? Parasitol Res 2007; 102:175-81. [PMID: 18026992 DOI: 10.1007/s00436-007-0779-1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2007] [Accepted: 10/24/2007] [Indexed: 10/22/2022]
Abstract
Africa accounts for about 33 and 90% of the world's burden of lymphatic filariasis (LF) and malaria, respectively. Despite tremendous progress in the approach to their diagnosis, epidemiology, and treatment, and global campaigns for their control and/or elimination, their global burden and economic costs have continued to rise. In most rural areas of the tropics, both diseases co-occur in the same human population and share common mosquito vectors. It is therefore conceived that control of the two diseases can be integrated using tools that have been proven effective recently or in the past. Before implementation of control programs in areas co-endemic for both diseases, it is deemed necessary to understand how the two diseases interact in the vector and human hosts. Here, we summarize available knowledge on coinfections of malaria and LF and provide an insight on how they can be managed.
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Abstract
Lymphatic filariasis has afflicted people in the tropical areas of the world for thousands of years but even up to comparatively recent times it has been poorly understood and its importance under recognised. In the last 2 decades or so there has been a flurry of activity in filariasis research, which has provided new insights into the global problem of filariasis, the pathogenesis of filarial disease, diagnosis and control.
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Affiliation(s)
- Wayne D Melrose
- Lymphatic Filariasis Support Centre, School of Public Health and Tropical Medicine, James Cook University, Townsville, QLD 4811, Australia.
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Buss DS, McCaffery AR, Callaghan A. Evidence for p-glycoprotein modification of insecticide toxicity in mosquitoes of the Culex pipiens complex. MEDICAL AND VETERINARY ENTOMOLOGY 2002; 16:218-222. [PMID: 12109718 DOI: 10.1046/j.1365-2915.2002.00365.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Pesticide resistance has parallels with multi-drug resistance syndrome of tumours in clinical medicine, which has been linked to an ATP-dependent pump, p-glycoprotein (P-gp). P-gps pump drugs out of the cell, thereby reducing cellular concentrations of the chemical. P-gps have been found in several invertebrate species and have been shown to provide a defence against environmental xenobiotics, including pesticides. This study used a model cell culture system to investigate the interaction of pesticides with P-gp. Ivermectin and endosulfan were shown to be strong inhibitors of dye transport out of cells, which is a standard measure of P-gp modulation. We then investigated the action of a P-gp inhibitor, verapamil (calcium channel blocker), on insecticide toxicity to fourth-instar mosquito larvae of the Culex pipiens L. complex (Diptera: Culicidae). Verapamil increased toxicity to examples of three insecticide classes (cypermethrin, endosulfan, ivermectin), but not to chlorpyrifos (organophosphate). The discovery of a novel protective mechanism in mosquitoes, with a wide substrate range, has implications for the control of important pest and vector species.
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Affiliation(s)
- D S Buss
- Division of Zoology, School of Animal & Microbial Sciences, The University of Reading, UK
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Foley DH, Bryan JH, Lawrence GW. The potential of ivermectin to control the malaria vector Anopheles farauti. Trans R Soc Trop Med Hyg 2000; 94:625-8. [PMID: 11198644 DOI: 10.1016/s0035-9203(00)90211-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We investigated mortality in Anopheles farauti mosquitoes, a major coastal malaria vector in the south-west Pacific, fed on a volunteer who had taken a 250 micrograms/kg dose of ivermectin. High mortality was recorded in mosquitoes feeding during the first week after treatment of the volunteer, for instance 100-80% failed to survive 3 days. A long-term residual effect of ivermectin in the blood was indicated by a small but significantly higher mortality in mosquitoes fed 6 weeks after ivermectin was taken. These effects were included in malaria transmission models that incorporated host choice and host-induced mortality parameters. For the zoophilic An. farauti, ivermectin treatment of animals resulted in a greater reduction in malaria than ivermectin treatment of humans alone, whereas for an anthropophilic vector, treatment of humans was more important. This suggests that ivermectin treatment of animals could have an important role in malaria control where An. farauti is the vector. Improvement in the health of humans and domestic animals through control of parasitic worms and mites might encourage community participation in strategies involving ivermectin.
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Affiliation(s)
- D H Foley
- Tropical Health Program, ACITHN, Australia.
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Hayes RJ, Alexander ND, Bennett S, Cousens SN. Design and analysis issues in cluster-randomized trials of interventions against infectious diseases. Stat Methods Med Res 2000; 9:95-116. [PMID: 10946429 DOI: 10.1177/096228020000900203] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This paper discusses the application of the cluster-randomized trial (CRT) design to evaluate the effectiveness of interventions against infectious diseases. In addition to the usual rationale for this design, there are a number of other advantages that are peculiar to the study of infectious diseases. In particular, CRTs are able to measure the overall effect of an intervention at the population level, capturing both the direct effect of an intervention on an individual's susceptibility to infection, and also the indirect effects due to changes in risks of transmission to other individuals, or to the mass effect or 'herd immunity' resulting from intervening in a large proportion of the population. We briefly review published CRTs of interventions against infectious diseases, most of which have been conducted in the developing countries where such diseases predominate. The focus is on trials in which communities or other large groupings are randomized, and in which impacts on infectious disease incidence or mortality are assessed. We then discuss three issues that are of special relevance to CRTs of infectious diseases. First, issues relating to the definition and size of clusters; secondly, the role of matching or stratification, and the choice of matching factors; and thirdly, the definition of direct and indirect effects of intervention, and methods of assessing these components in a CRT. We conclude by outlining some areas for future research.
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Affiliation(s)
- R J Hayes
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, UK.
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