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Kamau Y, Tuwei M, Wanjiku C, Ominde K, Ngama M, Karisa J, Babu L, Muturi M, Mwatasa M, Adetifa J, Kern C, Duthaler U, Hammann F, Rabinovich R, Chaccour C, Maia MF. Mosquitocidal efficacy and pharmacokinetics of single-dose ivermectin versus three-day dose regimen for malaria vector control compared with albendazole and no treatment: An open-label randomized controlled trial. Int J Infect Dis 2024; 148:107236. [PMID: 39245314 DOI: 10.1016/j.ijid.2024.107236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 08/02/2024] [Accepted: 09/03/2024] [Indexed: 09/10/2024] Open
Abstract
OBJECTIVES When malaria vectors consume ivermectin in a blood meal, their survival probability decreases, potentially reducing malaria transmission during mass drug administrations. However, questions remain regarding the optimal dosing. This study aimed to compare the mosquitocidal effect and pharmacokinetics of two-dose regimens of ivermectin for malaria vector control. DESIGN We conducted an open-label randomized control trial in Kenya, staggered in blocks with sequential intervention groups and parallel controls. Participants were randomly assigned (2:1:1:1) using computer random-sequence generation, unstratified, with one block of six pharmacokinetics-only participants (single-dose ivermectin) and six blocks of four participants (3:1 intervention vs control), to receive single-dose ivermectin (400 mcg/kg, n = 12), three daily doses (3-day regimen 300 mcg/kg, n = 6), albendazole (400 mg, n = 6), or no treatment (negative control, n = 6). Our primary outcome was Anopheles gambiae survival (time-to-event [days]) after blood feeding up to 10 days after drug administration. We also evaluated pharmacokinetics (peak plasma and capillary blood concentration, areas under the plasma and capillary blood concentration-time curve from time of last administration to time of last observation, time to reach peak plasma and capillary blood concentration, terminal elimination half-life) up to 7 days after treatment. RESULTS A total of 36 healthy volunteers aged 21-32 years were recruited into the study and followed up to completion, with two participants not attending the visit on day 28. All drug regimens were well-tolerated. Both regimens showed significant mosquitocidal effect in the first 7 days. At 10 days after treatment, the single dose presented superior longevity of effect (adjusted hazard ratio = 3.91; 95% confidence interval = 1.93-7.93; P <0.001) compared with the triple dose (adjusted hazard ratio = 1.79; 95% confidence interval = 0.88-3.62; P = 0.0.11). Albendazole had, overall, no mosquitocidal effect. CONCLUSIONS It is unclear why a single dose led to increased bio-efficacy compared with a triple dose. We recommend trials investigating ivermectin mass drug administrations for malaria control to consider single-dose ivermectin. A single-dose regimen is also expected to present additional operational advantages compared with a 3-day regimen, leading to improved programmatic suitability.
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Affiliation(s)
- Yvonne Kamau
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mercy Tuwei
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Caroline Wanjiku
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Kelly Ominde
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mwanajuma Ngama
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jonathan Karisa
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Lawrence Babu
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Martha Muturi
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Mwaganyuma Mwatasa
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Jane Adetifa
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Charlotte Kern
- Division of Clinical Pharmacology & Toxicology of Internal Medicine, University Hospital of Bern, Bern, Switzerland; Graduate School for Health Sciences, University of Bern, Bern, Switzerland
| | - Urs Duthaler
- Institute of Forensic Medicine, Department of Biomedical Engineering, University of Basel, Basel, Switzerland; Department of Pharmaceutical Sciences, Division of Clinical Pharmacology & Toxicology, University of Basel, Basel, Switzerland; Division of Clinical Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Felix Hammann
- Division of Clinical Pharmacology & Toxicology of Internal Medicine, University Hospital of Bern, Bern, Switzerland
| | - Regina Rabinovich
- Harvard T.H. Chan School of Public Health, Boston, USA; Barcelona Institute for Global Health, Barcelona, Spain
| | - Carlos Chaccour
- Barcelona Institute for Global Health, Barcelona, Spain; CIBERINFEC, Madrid, Spain; University of Navarra, Pamplona, Spain
| | - Marta Ferreira Maia
- Department of Clinical Trials, KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya; Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.
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Shepherd-Gorringe MAM, Pettit MW, Hawkes FM. Lethal and sublethal impacts of membrane-fed ivermectin are concentration dependent in Anopheles coluzzii. Parasit Vectors 2024; 17:228. [PMID: 38755640 PMCID: PMC11100210 DOI: 10.1186/s13071-024-06287-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/18/2024] [Indexed: 05/18/2024] Open
Abstract
BACKGROUND Ivermectin is a well-tolerated anthelminthic drug with wide clinical and veterinary applications. It also has lethal and sublethal effects on mosquitoes. Mass drug administration with ivermectin has therefore been suggested as an innovative vector control tool in efforts to curb emerging insecticide resistance and reduce residual malaria transition. To support assessments of the feasibility and efficacy of current and future formulations of ivermectin for vector control, we sought to establish the relationship between ivermectin concentration and its lethal and sublethal impacts in a primary malaria vector. METHODS The in vitro effects of ivermectin on daily mortality and fecundity, measured by egg production, were assessed up to 14 days post-blood feed in a laboratory colony of Anopheles coluzzii. Mosquitoes were fed ivermectin in blood meals delivered by membrane feeding at one of six concentrations: 0 ng/ml (control), 10 ng/ml, 15 ng/ml, 25 ng/ml, 50 ng/ml, 75 ng/ml, and 100 ng/ml. RESULTS Ivermectin had a significant effect on mosquito survival in a concentration-dependent manner. The LC50 at 7 days was 19.7 ng/ml. The time to median mortality at ≥ 50 ng/ml was ≤ 4 days, compared to 9.6 days for control, and 6.3-7.6 days for ivermectin concentrations between 10 and 25 ng/ml. Fecundity was also affected; no oviposition was observed in surviving females from the two highest concentration treatment groups. While females exposed to 10 to 50 ng/ml of ivermectin did oviposit, significantly fewer did so in the 50 ng/ml treatment group compared to the control, and they also produced significantly fewer eggs. CONCLUSIONS Our results showed ivermectin reduced mosquito survival in a concentration-dependent manner and at ≥ 50 ng/ml significantly reduced fecundity in An. coluzzii. Results indicate that levels of ivermectin found in human blood following ingestion of a single 150-200 μg/kg dose would be sufficient to achieve 50% mortality across 7 days; however, fecundity in survivors is unlikely to be affected. At higher doses, a substantial impact on both survival and fecundity is likely. Treating human populations with ivermectin could be used as a supplementary malaria vector control method to kill mosquito populations and supress their reproduction; however strategies to safely maintain mosquitocidal blood levels of ivermectin against all Anopheles species require development.
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Affiliation(s)
- Monique A M Shepherd-Gorringe
- Medway Centre for Pharmaceutical Science, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK.
- Natural Resources Institute, University of Greenwich at Medway, Chatham Maritime, Kent, ME4 4TB, UK.
| | - Marie W Pettit
- Medway Centre for Pharmaceutical Science, University of Greenwich, Chatham Maritime, Kent, ME4 4TB, UK
| | - Frances M Hawkes
- Natural Resources Institute, University of Greenwich at Medway, Chatham Maritime, Kent, ME4 4TB, UK
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Huang Y, Chen Z, Lan J, Zhang L, Chen H, Jiang L, Yu H, Liu N, Liao C, Han Q. MDR49 coding for both P-glycoprotein and TMOF transporter functions in ivermectin resistance, trypsin activity inhibition, and fertility in the yellow fever mosquito, Aedes aegypti. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2024; 201:105899. [PMID: 38685208 DOI: 10.1016/j.pestbp.2024.105899] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Revised: 03/30/2024] [Accepted: 04/06/2024] [Indexed: 05/02/2024]
Abstract
This study investigated the function of the MDR49 gene in Aedes aegypti. MDR49 mutants were constructed using CRISPR/Cas9 technology; the mutation led to increased sensitivity to ivermectin (LC50: from 1.3090 mg L-1 to 0.5904 mg L-1), and a reduction in midgut trypsin activity. These findings suggest that the P-gp encoded by MDR49 confers resistance to ivermectin and impacts the reproductive function in Ae. aegypti. RNA interference technology showed that knockdown of MDR49 gene resulted in a significant decrease in the expression of VGA1 after a blood meal, as well as a decrease in the number of eggs laid and their hatching rate. LC-MS revealed that following ivermectin treatment, the MDR493d+2s/3d+2s strain larvae exhibited significantly higher drug concentrations in the head and fat body compared to the wild type. Modeling of inward-facing P-gp and molecular docking found almost no difference in the affinity of P-gp for ivermectin before and after the mutation. However, modeling of the outward-facing conformation demonstrated that the flexible linker loop between TM5 and TM6 of P-gp undergoes changes after the mutation, resulting in a decrease in trypsin activity and an increase in sensitivity to ivermectin. These results provide useful insights into ivermectin resistance and the other roles played by the MDR49 gene.
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Affiliation(s)
- Yuqi Huang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Zhaohui Chen
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Jianqiang Lan
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Lei Zhang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Huaqing Chen
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Linlong Jiang
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Hongxiao Yu
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China
| | - Nannan Liu
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36830, USA
| | - Chenghong Liao
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China.
| | - Qian Han
- Laboratory of Tropical Veterinary Medicine and Vector Biology, School of Life and Health Sciences, Hainan University, Haikou, Hainan 570228, China; One Health Institute, Hainan University, Haikou, Hainan 570228, China.
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Cramer EY, Nguyen XQ, Hertz JC, Nguyen DV, Quang HH, Mendenhall IH, Lover AA. Measuring effects of ivermectin-treated cattle on potential malaria vectors in Vietnam: A cluster-randomized trial. PLoS Negl Trop Dis 2024; 18:e0012014. [PMID: 38683855 PMCID: PMC11098492 DOI: 10.1371/journal.pntd.0012014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 05/16/2024] [Accepted: 02/19/2024] [Indexed: 05/02/2024] Open
Abstract
BACKGROUND Malaria elimination using current tools has stalled in many areas. Ivermectin (IVM) is a broad-antiparasitic drug and mosquitocide and has been proposed as a tool for accelerating progress towards malaria elimination. Under laboratory conditions, IVM has been shown to reduce the survival of adult Anopheles populations that have fed on IVM-treated mammals. Treating cattle with IVM has been proposed as an important contribution to malaria vector management, however, the impacts of IVM in this One Health use case have been untested in field trials in Southeast Asia. METHODS Through a randomized village-based trial, this study quantified the effect of IVM-treated cattle on anopheline populations in treated vs. untreated villages in Central Vietnam. Local zebu cattle in six rural villages were included in this study. In three villages, cattle were treated with IVM at established veterinary dosages, and in three additional villages cattle were left as untreated controls. For the main study outcome, the mosquito populations in all villages were sampled using cattle-baited traps for six nights before, and six nights after a 2-day IVM-administration (intervention) period. Anopheline species were characterized using taxonomic keys. The impact of the intervention was analyzed using a difference-in-differences (DID) approach with generalized estimating equations (with negative binomial distribution and robust errors). This intervention was powered to detect a 50% reduction in total nightly Anopheles spp. vector catches from cattle-baited traps. Given the unusual diversity in anopheline populations, exploratory analyses examined taxon-level differences in the ecological population diversity. RESULTS Across the treated villages, 1,112 of 1,523 censused cows (73% overall; range 67% to 83%) were treated with IVM. In both control and treated villages, there was a 30% to 40% decrease in total anophelines captured in the post-intervention period as compared to the pre-intervention period. In the control villages, there were 1,873 captured pre-intervention and 1,079 captured during the post-intervention period. In the treated villages, there were 1,594 captured pre-intervention, and 1,101 captured during the post-intervention period. The difference in differences model analysis comparing total captures between arms was not statistically significant (p = 0.61). Secondary outcomes of vector population diversity found that in three villages (one control and two treatment) Brillouin's index increased, and in three villages (two control and one treatment) Brillouin's index decreased. When examining biodiversity by trapping-night, there were no clear trends in treated or untreated vector populations. Additionally, there were no clear trends when examining the components of biodiversity: richness and evenness. CONCLUSIONS The ability of this study to quantify the impacts of IVM treatment was limited due to unexpectedly large spatiotemporal variability in trapping rates; an area-wide decrease in trapping counts across all six villages post-intervention; and potential spillover effects. However, this study provides important data to directly inform future studies in the GMS and beyond for IVM-based vector control.
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Affiliation(s)
- Estee Y. Cramer
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Massachusetts, United States of America
| | - Xuan Quang Nguyen
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | | | - Do Van Nguyen
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | - Huynh Hong Quang
- Institute of Malariology-Parasitology & Entomology Quy Nhon, Ministry of Health, Vietnam
| | - Ian H. Mendenhall
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore
| | - Andrew A. Lover
- Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts-Amherst, Massachusetts, United States of America
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Shah HK, Srinivasan V, Venkatesan S, Balakrishnan V, Candasamy S, Mathew N, Kumar A, Kuttiatt VS. Evaluation of the mosquitocidal efficacy of fluralaner, a potential candidate for drug based vector control. Sci Rep 2024; 14:5628. [PMID: 38454095 PMCID: PMC10920869 DOI: 10.1038/s41598-024-56053-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 03/01/2024] [Indexed: 03/09/2024] Open
Abstract
Vector control is a key intervention against mosquito borne diseases. However, conventional methods have several limitations and alternate strategies are in urgent need. Vector control with endectocides such as ivermectin is emerging as a novel strategy. The short half-life of ivermectin is a limiting factor for its application as a mass therapy tool for vector control. Isoxazoline compounds like fluralaner, a class of veterinary acaricides with long half-life hold promise as an alternative. However, information about their mosquitocidal effect is limited. We explored the efficacy of fluralaner against laboratory reared vector mosquitoes-Aedes aegypti, Anopheles stephensi, and, Culex quinquefasciatus. 24 h post-blood feeding, fluralaner showed a significant mosquitocidal effect with LC50 values in the range of 24.04-49.82 ng/mL for the three different mosquito species tested. Effects on life history characteristics (fecundity, egg hatch success, etc.) were also observed and significant effects were noted at drug concentrations of 20, 25 and 45 ng/mL for Ae. aegypti, An. stephensi, and, Cx. quinquefasciatus respectively. At higher drug concentration of 250 ng/mL, significant mortality was observed within 1-2 h of post blood feeding. Potent mosquitocidal effect coupled with its long half-life makes fluralaner an excellent candidate for drug based vector control strategies.
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Affiliation(s)
| | | | | | | | | | - Nisha Mathew
- ICMR-Vector Control Research Centre, Puducherry, 605 006, India
| | - Ashwani Kumar
- ICMR-Vector Control Research Centre, Puducherry, 605 006, India
- Saveetha Institute of Medical and Technical Sciences, Saveetha University, Thandalam, Kanchipuram, 602 105, India
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Zeleke G, Duchateau L, Yewhalaw D, Suleman S, Devreese M. In-vitro susceptibility and ex-vivo evaluation of macrocyclic lactone endectocides sub-lethal concentrations against Plasmodium vivax oocyst development in Anopheles arabiensis. Malar J 2024; 23:26. [PMID: 38238768 PMCID: PMC10797976 DOI: 10.1186/s12936-024-04845-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 01/05/2024] [Indexed: 01/22/2024] Open
Abstract
BACKGROUND Asymptomatic malaria transmission has become a public health concern across malaria-endemic Africa including Ethiopia. Specifically, Plasmodium vivax is more efficient at transmitting earlier in the infection and at lower densities than Plasmodium falciparum. Consequently, a greater proportion of individuals infected with P. vivax can transmit without detectable gametocytaemia. Mass treatment of livestock with macrocyclic lactones (MLs), e.g., ivermectin and doramectin, was suggested as a complementary malaria vector tool because of their insecticidal effects. However, the effects of MLs on P. vivax in Anopheles arabiensis has not yet been fully explored. Hence, comparative in-vitro susceptibility and ex-vivo studies were conducted to evaluate the effects of ivermectin, doramectin and moxidectin sub-lethal concentrations on P. vivax oocyst development in An. arabiensis. METHODS The 7-day sub-lethal concentrations of 25% (LC25) and 5% (LC5) were determined from in-vitro susceptibility tests on female An. arabiensis in Hemotek® membrane feeding assay. Next, an ex-vivo study was conducted using P. vivax gametocytes infected patient's blood spiked with the LC25 and LC5 of the MLs. At 7-days post-feeding, each mosquito was dissected under a dissection stereo microscope, stained with 0.5% (w/v) mercurochrome solution, and examined for the presence of P. vivax oocysts. Statistical analysis was based on a generalized mixed model with binomially distributed error terms. RESULTS A 7-day lethal concentration of 25% (LC25, in ng/mL) of 7.1 (95% CI: [6.3;8.0]), 20.0 (95%CI:[17.8;22.5]) and 794.3 (95%CI:[716.4;1516.3]) were obtained for ivermectin, doramectin and moxidectin, respectively. Similarly, a lethal concentration of 5% (LC5, in ng/mL) of 0.6 (95% CI: [0.5;0.7]), 1.8 (95% CI:[1.6;2.0]) and 53.7 (95% CI:[ 48.4;102.5]) were obtained respectively for ivermectin, doramectin and moxidectin. The oocyst prevalence in treatment and control groups did not differ significantly (p > 0.05) from each other. Therefore, no direct effect of ML endectocides on P. vivax infection in An. arabiensis mosquitoes was observed at the sub-lethal concentration (LC25 and LC5). CONCLUSIONS The effects of ivermectin and doramectin on malaria parasite is more likely via indirect effects, particularly by reducing the vectors lifespan and causing mortality before completing the parasite's sporogony cycle or reducing their vector capacity as it affects the locomotor activity of the mosquito.
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Affiliation(s)
- Gemechu Zeleke
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
- Jimma University Laboratory of Drug Quality (JuLaDQ), and School of Pharmacy, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Luc Duchateau
- Biometrics Research Center, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium
| | - Delenasaw Yewhalaw
- School of Medical Laboratory Sciences, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Sultan Suleman
- Jimma University Laboratory of Drug Quality (JuLaDQ), and School of Pharmacy, Institute of Health, Jimma University, Jimma, Ethiopia
| | - Mathias Devreese
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke, Belgium.
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Damene E, Massebo F. Administration of ivermectin to cattle induced mortality, reduced fecundity and survivorship of Anopheles arabiensis in Ethiopia: an implication for expansion of vector control toolbox. Trop Med Health 2024; 52:11. [PMID: 38229204 PMCID: PMC10790479 DOI: 10.1186/s41182-023-00575-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 12/27/2023] [Indexed: 01/18/2024] Open
Abstract
BACKGROUND Although many countries have shown interest in eliminating malaria, approaches that complement existing vector control interventions are needed because existing methods have been scaled up but malaria still persists. Therefore, the effect of ivermectin administration to cattle was evaluated for its effect on mortality, survivorship and mortality of laboratory reared Anopheles arabiensis. METHODS Three calves were randomly selected and injected with ivermectin at a therapeutic dose of 0.2 mg/kg, while the other two calves received no treatment and served as controls. Five tents were constructed for the trial. Calves were housed in tents (one per tent) and then 30 starved female An. arabiensis were introduced into each tent. Only fully engorged females were collected from each tent and placed in different mosquito cages to monitor their mortality, survival and fecundity. Data analysis was done using SPSS version 16. RESULTS During the follow-up period (until day 21), ivermectin induced significantly higher mortality when compared to controls. It resulted in an average 24-h mortality rate of 81.6% against An. arabiensis on the first day following treatment. 100% An. arabiensis that fed on ivermectin-treated calves on the first day after treatment died within four days. Egg production rate of An. arabiensis that fed on ivermectin-treated calves was significantly lower compared to controls (F = 768.7, P < 0.001). CONCLUSION In conclusion, ivermectin induced mortality, reduced fecundity and survivorship of laboratory maintained An. arabiensis. Further study is recommended using a wild mosquito population. Moreover, mass ivermectin administration to domestic animals could be recommended to supplement the existing indoor based interventions.
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Affiliation(s)
- Ephrem Damene
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia
| | - Fekadu Massebo
- Department of Biology, Arba Minch University, Arba Minch, Ethiopia.
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Kiuru C, Ominde K, Muturi M, Babu L, Wanjiku C, Chaccour C, Maia MF. Effects of larval exposure to sublethal doses of ivermectin on adult fitness and susceptibility to ivermectin in Anopheles gambiae s.s. Parasit Vectors 2023; 16:293. [PMID: 37605264 PMCID: PMC10441747 DOI: 10.1186/s13071-023-05888-w] [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: 03/01/2023] [Accepted: 07/18/2023] [Indexed: 08/23/2023] Open
Abstract
BACKGROUND The effects of ivermectin (endectocide) on mosquito survival make it a potential new malaria vector control tool. The drug can be administered to mosquito disease vectors through blood hosts that include humans and livestock. Its increased use may cause contamination of larval habitats, either directly through livestock excreta or indirectly through leaching or run-off from contaminated soil, albeit in sublethal doses. However, the effects of such exposure on immature stages and the subsequent adults that emerge are poorly understood. This study was undertaken to evaluate the impact of ivermectin exposure on Anopheles gambiae s.s. larvae and its effects on fitness and susceptibility to ivermectin in the emerging adults. METHODS Laboratory-reared An. gambiae s.s. (Kilifi strain) larvae were exposed to five different ivermectin concentrations; 0, 0.00001, 0.0001, 0.001, and 0.01 ppm, and larval survival was monitored to determine the appropriate sub-lethal dose. Concentrations with survival > 50% (0.00001 and 0.0001 ppm) were selected and used as the sub-lethal doses. The fecundity, fertility, and susceptibility to ivermectin of adults emerging after larval exposure to the sub-lethal doses were examined. RESULTS Overall, exposure of An. gambiae s.s. aquatic stages to ivermectin caused a dose-dependent reduction in larval survival irrespective of the stage at which the larvae were exposed. Exposure to ivermectin in the larval stage did not have an effect on either the number of eggs laid or the hatch rate. However, exposure of first/second-instar larvae to 0.0001 ppm and third/fourth-instar larvae to 0.001 ppm of ivermectin reduced the time taken to oviposition. Additionally, exposure to ivermectin in the larval stage did not affect susceptibility of the emerging adults to the drug. CONCLUSIONS This study shows that contamination of larval habitats with ivermectin affects An. gambiae s.s. larval survival and could potentially have an impact on public health. However, there are no carry-over effects on the fecundity, fertility, and susceptibility of the emerging adults to ivermectin. In addition, this study shows that environmental exposure to ivermectin in the larval habitats is unlikely to compromise the efficacy of ivermectin in the emerging adults.
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Affiliation(s)
- Caroline Kiuru
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036, Barcelona, Spain.
- Centro de Investigação em Saúde de Manhiça (CISM), Maputo, Mozambique.
| | - Kelly Ominde
- Department of Biosciences, KEMRI Wellcome Trust Research Programme (KWTRP), Kilifi, 230-80108, Kenya
- Pwani University, Department of Biological Sciences and Pwani University Bioscience Research Centre (PUBReC), Kilifi, Kenya
| | - Martha Muturi
- Department of Biosciences, KEMRI Wellcome Trust Research Programme (KWTRP), Kilifi, 230-80108, Kenya
| | - Lawrence Babu
- Department of Biosciences, KEMRI Wellcome Trust Research Programme (KWTRP), Kilifi, 230-80108, Kenya
| | - Caroline Wanjiku
- Department of Biosciences, KEMRI Wellcome Trust Research Programme (KWTRP), Kilifi, 230-80108, Kenya
| | - Carlos Chaccour
- Barcelona Institute for Global Health (ISGlobal), Hospital Clínic - Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036, Barcelona, Spain
- Facultad de Medicina, Universidad de Navarra, 31008, Pamplona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Infecciosas, Madrid, Spain
| | - Marta Ferreira Maia
- Department of Biosciences, KEMRI Wellcome Trust Research Programme (KWTRP), Kilifi, 230-80108, Kenya.
- Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK.
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9
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Schluth CG, Standley CJ, Bansal S, Carlson CJ. Spatial parasitology and the unmapped human helminthiases. Parasitology 2023; 150:1-9. [PMID: 36632014 PMCID: PMC10090474 DOI: 10.1017/s0031182023000045] [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: 08/28/2022] [Revised: 12/29/2022] [Accepted: 01/04/2023] [Indexed: 01/13/2023]
Abstract
Helminthiases are a class of neglected tropical diseases that affect at least 1 billion people worldwide, with a disproportionate impact on resource-poor areas with limited disease surveillance. Geospatial methods can offer valuable insights into the burden of these infections, particularly given that many are subject to strong ecological influences on the environmental, vector-borne or zoonotic stages of their life cycle. In this study, we screened 6829 abstracts and analysed 485 studies that use maps to document, infer or predict transmission patterns for over 200 species of parasitic worms. We found that quantitative mapping methods are increasingly used in medical parasitology, drawing on One Health surveillance data from the community scale to model geographic distributions and burdens up to the regional or global scale. However, we found that the vast majority of the human helminthiases may be entirely unmapped, with research effort focused disproportionately on a half-dozen infections that are targeted by mass drug administration programmes. Entire regions were also surprisingly under-represented in the literature, particularly southern Asia and the Neotropics. We conclude by proposing a shortlist of possible priorities for future research, including several neglected helminthiases with a burden that may be underestimated.
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Affiliation(s)
| | - Claire J. Standley
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC, USA
- Center for Global Health Science and Security, Georgetown University Medical Center, Washington, DC, USA
| | - Shweta Bansal
- Department of Biology, Georgetown University, Washington, DC, USA
| | - Colin J. Carlson
- Department of Biology, Georgetown University, Washington, DC, USA
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC, USA
- Center for Global Health Science and Security, Georgetown University Medical Center, Washington, DC, USA
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10
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Eba K, Habtewold T, Asefa L, Degefa T, Yewhalaw D, Duchateau L. Effect of Ivermectin ® on survivorship and fertility of Anopheles arabiensis in Ethiopia: an in vitro study. Malar J 2023; 22:12. [PMID: 36624480 PMCID: PMC9830892 DOI: 10.1186/s12936-023-04440-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 01/03/2023] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND Innovative vector control tools are needed to counteract insecticide resistance and residual malaria transmission. One of such innovative methods is an ivermectin (IVM) treatment to reduce vector survival. In this study, a laboratory experiment was conducted to investigate the effect of ivermectin on survivorship, fertility and egg hatchability rate of Anopheles arabiensis in Ethiopia. METHODS An in vitro experiment was conducted using 3-5 days old An. arabiensis adults from a colony maintained at insectary of Tropical and Infectious Diseases Research Center, Jimma University (laboratory population) and Anopheles mosquitoes reared from larvae collected from natural mosquito breeding sites (wild population). The mosquitoes were allowed to feed on cattle blood treated with different doses of ivermectin (0 ng/ml, 5 ng/ml, 10 ng/ml, 20 ng/ml, 40 ng/ml and 80 ng/ml). During each feeding experiment, the mosquitoes were held in cages and blood-fed using a Hemotek feeder. Mortality and egg production were then recorded daily for up to 9 days. Time to death was analysed by a Cox frailty model with replicate as frailty term and source of mosquito (wild versus laboratory), treatment type (ivermectin vs control) and their interaction as categorical fixed effects. Kaplan Meier curves were plotted separately for wild and laboratory populations for a visual interpretation of mosquito survival as a function of treatment. RESULTS Both mosquito source and treatment had a significant effect on survival (P < 0.001), but their interaction was not significant (P = 0.197). Compared to the controls, the death hazard of An. arabiensis that fed on ivermectin-treated blood was 2.3, 3.5, 6.5, 11.5 and 17.9 times that of the control for the 5 ng/ml, 10 ng/ml, 20 ng/ml, 40 ng/ml, and 80 ng/ml dose, respectively. With respect to the number of hatched larvae, hatched pupae and emerged adults per fed mosquitoes, a significant difference was found between the control and the 5 ng/ml dose group (P < 0.001). The number of hatched larvae and pupae, and emerged adults decreased further for the 10 ng/ml dose group and falls to zero for the higher doses. CONCLUSION Treating cattle blood with ivermectin reduced mosquito survival, fertility, egg hatchability, larval development and adult emergence of An. arabiensis in all tested concentrations of ivermectin in both the wild and laboratory populations. Thus, ivermectin application in cattle could be used as a supplementary vector control method to tackle residual malaria transmission and ultimately achieve malaria elimination in Ethiopia.
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Affiliation(s)
- Kasahun Eba
- grid.411903.e0000 0001 2034 9160Department of Environmental Health Science and Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Tibebu Habtewold
- grid.7445.20000 0001 2113 8111Department of Life Sciences, Imperial College London, London, UK
| | - Lechisa Asefa
- grid.411903.e0000 0001 2034 9160Department of Environmental Health Science and Technology, Jimma University, P.O. Box 378, Jimma, Ethiopia ,grid.472427.00000 0004 4901 9087Department of Environmental Health Sciences, Bule Hora University, P.O. Box 144, Bule Hora, Ethiopia
| | - Teshome Degefa
- grid.411903.e0000 0001 2034 9160School of Medical Laboratory Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Delenasaw Yewhalaw
- grid.411903.e0000 0001 2034 9160School of Medical Laboratory Sciences, Jimma University, P.O. Box 378, Jimma, Ethiopia ,grid.411903.e0000 0001 2034 9160Tropical and Infectious Diseases Research Center, Jimma University, P.O. Box 378, Jimma, Ethiopia
| | - Luc Duchateau
- grid.5342.00000 0001 2069 7798Biometrics Research Center, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
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11
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Soumare HM, Dabira ED, Camara MM, Jadama L, Gaye PM, Kanteh S, Jawara EA, Njie AK, Sanneh F, Ndiath MO, Lindsay SW, Conteh B, Ceesay S, Mohammed N, Ooko M, Bradley J, Drakeley C, Erhart A, Bousema T, D’Alessandro U. Entomological impact of mass administration of ivermectin and dihydroartemisinin-piperaquine in The Gambia: a cluster-randomized controlled trial. Parasit Vectors 2022; 15:435. [PMID: 36397132 PMCID: PMC9673448 DOI: 10.1186/s13071-022-05557-4] [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: 07/06/2022] [Accepted: 10/16/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Vector control interventions in sub-Saharan Africa rely on insecticide-treated nets and indoor residual spraying. Insecticide resistance, poor coverage of interventions, poor quality nets and changes in vector behavior threaten the effectiveness of these interventions and, consequently, alternative tools are needed. Mosquitoes die after feeding on humans or animals treated with ivermectin (IVM). Mass drug administration (MDA) with IVM could reduce vector survival and decrease malaria transmission. The entomological impact of MDA of combined IVM and dihydroartemisinin-piperaquine was assessed in a community-based, cluster-randomized trial. METHODS A cluster-randomized trial was implemented in 2018 and 2019 in 32 villages in the Upper River Region, The Gambia. The with the inhabitants of 16 intervention villages eligible to receive three monthly rounds of MDA at the beginning of the malaria transmission season. Entomological surveillance with light traps and human landing catches (HLC) was carried out during a 7- to 14-day period after each round of MDA, and then monthly until the end of the year. The mosquitocidal effect of IVM was determined by direct membrane feeding assays. RESULTS Of the 15,017 mosquitoes collected during the study period, 99.65% (n = 14,965) were Anopheles gambiae sensu lato (An. gambiae s.l.), comprising Anopheles arabiensis (56.2%), Anopheles coluzzii (24.5%), Anopheles gambiae sensu stricto (An. gembiae s.s.; 16.0%) and Anopheles funestus sensu lato (An. funestus s.l.; 0.35%). No effect of the intervention on vector parity was observed. Vector density determined on light trap collections was significantly lower in the intervention villages in 2019 (adjusted incidence rate ratio: 0.39; 95% confidence interval [CI]: 0.20, 0.74; P = 0.005) but not in 2018. However, vector density determined in HLC collections was similar in both the intervention and control villages. The entomological inoculation rate was significantly lower in the intervention villages than in the control villages (odds ratio: 0.36, 95% CI: 0.19, 0.70; P = 0·003). Mosquito mortality was significantly higher when blood fed on IVM-treated individuals up to 21 days post-treatment, particularly in adults and individuals with a higher body mass index. CONCLUSION Mass drug administration with IVM decreased vector density and the entomological inoculation rate while the effect on vector parity was less clear. Survival of mosquitoes fed on blood collected from IVM-treated individuals was significantly lower than that in mosquitoes which fed on controls. The influence of host characteristics on mosquito survivorship indicated that dose optimization could improve IVM efficacy. Future detailed entomological evaluation trials in which IVM is administered as stand-alone intervention may elucidate the contribution of this drug to the observed reduction in transmission.
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Affiliation(s)
- Harouna M. Soumare
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Edgard Diniba Dabira
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Muhammed M. Camara
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Lamin Jadama
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Pa Modou Gaye
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sainey Kanteh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Ebrima A. Jawara
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Amie Kolleh Njie
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Fatou Sanneh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Mamadou Ousman Ndiath
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | | | - Bakary Conteh
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Sainey Ceesay
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Nuredin Mohammed
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Michael Ooko
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Chris Drakeley
- Faculty of Infectious & Tropical Diseases, The London School of Hygiene and Tropical Medicine, London, UK
| | - Annette Erhart
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | - Teun Bousema
- Radboud Institute for Health Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Umberto D’Alessandro
- Medical Research Council Unit The Gambia at the London, School of Hygiene and Tropical Medicine, Banjul, The Gambia
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12
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Djihinto OY, Medjigbodo AA, Gangbadja ARA, Saizonou HM, Lagnika HO, Nanmede D, Djossou L, Bohounton R, Sovegnon PM, Fanou MJ, Agonhossou R, Akoton R, Mousse W, Djogbénou LS. Malaria-Transmitting Vectors Microbiota: Overview and Interactions With Anopheles Mosquito Biology. Front Microbiol 2022; 13:891573. [PMID: 35668761 PMCID: PMC9164165 DOI: 10.3389/fmicb.2022.891573] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 05/04/2022] [Indexed: 11/20/2022] Open
Abstract
Malaria remains a vector-borne infectious disease that is still a major public health concern worldwide, especially in tropical regions. Malaria is caused by a protozoan parasite of the genus Plasmodium and transmitted through the bite of infected female Anopheles mosquitoes. The control interventions targeting mosquito vectors have achieved significant success during the last two decades and rely mainly on the use of chemical insecticides through the insecticide-treated nets (ITNs) and indoor residual spraying (IRS). Unfortunately, resistance to conventional insecticides currently being used in public health is spreading in the natural mosquito populations, hampering the long-term success of the current vector control strategies. Thus, to achieve the goal of malaria elimination, it appears necessary to improve vector control approaches through the development of novel environment-friendly tools. Mosquito microbiota has by now given rise to the expansion of innovative control tools, such as the use of endosymbionts to target insect vectors, known as "symbiotic control." In this review, we will present the viral, fungal and bacterial diversity of Anopheles mosquitoes, including the bacteriophages. This review discusses the likely interactions between the vector microbiota and its fitness and resistance to insecticides.
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Affiliation(s)
- Oswald Y. Djihinto
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Adandé A. Medjigbodo
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Albert R. A. Gangbadja
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Helga M. Saizonou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Hamirath O. Lagnika
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Dyane Nanmede
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Laurette Djossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Roméo Bohounton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Pierre Marie Sovegnon
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Marie-Joel Fanou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Romuald Agonhossou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Romaric Akoton
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Wassiyath Mousse
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
| | - Luc S. Djogbénou
- Tropical Infectious Diseases Research Centre (TIDRC), University of Abomey-Calavi, Cotonou, Benin
- Regional Institute of Public Health, University of Abomey-Calavi, Ouidah, Benin
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13
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Amelia-Yap ZH, Azman AS, AbuBakar S, Low VL. Streptomyces derivatives as an insecticide: Current perspectives, challenges and future research needs for mosquito control. Acta Trop 2022; 229:106381. [PMID: 35183537 DOI: 10.1016/j.actatropica.2022.106381] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/16/2022] [Accepted: 02/16/2022] [Indexed: 12/13/2022]
Abstract
The pervasiveness of arboviruses in wreaking havoc on public health has lingered on international health agendas. A scarcity of mosquito-borne disease vaccines and therapies demands prompt attention, as billions of people worldwide are at risk of infections. It is widely known that vector control continues, and in some diseases, remains the only resort in suppressing disease transmissions we presently possess at its disposal. But the use of commercial insecticides is being crippled by the widespread insecticide resistance, which greatly menaces their efficacies, toxicological repercussions such as environmental pollution and human health risk. Rather, an environmentally benign technique of employing Streptomyces isolates from settings such as terrestrial soils, marine sediments, and mangrove soils for Culicidae management has recently received a lot of positive attention. Streptomyces' capacities to produce a wide range of bioactive secondary metabolites that contribute to pharmaceutical, agricultural and veterinarian, Streptomyces-derived bioactive compounds are increasingly being considered for use in vector control. Herein, we compiled all of the available datasets on the effectiveness of Streptomyces-derived compounds against major mosquito vectors of medical importance. Aedes, Anopheles, and Culex are used to assess the toxicity of crude extracts or fractions. This paper reviewed the promising ovicidal, larvicidal, and pupacidal effects of different Streptomyces strains. Notably, no research into the adulticidal effect of Streptomyces-derived compounds has yet been done. Aside from the genetic makeup, the production of secondary metabolites from Streptomyces depends on the growing conditions. And that, to optimise the maximum yield of highly potent bioactive compounds being extracted, solvents' choice is of paramount importance. Thus, both cultivation parameters and the choice of organic solvents for secondary metabolites extraction will be discussed. Furthermore, biases derived from different studies have implied the need for standardizing experimental procedures. While entomological data should be collected consistently across all studies to expedite evidence-based policymaking of bioinsecticides, the quality of data from vector control interventions - particularly the experimental design, execution, analysis, and presentation of results of vector control studies - will be thoroughly reviewed. Lastly, to promote consistency and reliability, these knowledge gaps are identified, along with a discussion of current perspectives on vector control, global bioinsecticide trends, challenges on commercializing bioinsecticides and future research needs.
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Affiliation(s)
- Zheng Hua Amelia-Yap
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Adzzie Shazleen Azman
- School of Science, Monash University Malaysia, Jalan Lagoon Selatan, Bandar Sunway, 47500, Malaysia
| | - Sazaly AbuBakar
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Van Lun Low
- Higher Institution Centre of Excellence (HICoE), Tropical Infectious Diseases Research and Education Centre (TIDREC), Universiti Malaya, Kuala Lumpur 50603, Malaysia.
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14
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Ahmad SS, Rahi M, Saroha P, Sharma A. Ivermectin as an endectocide may boost control of malaria vectors in India and contribute to elimination. Parasit Vectors 2022; 15:20. [PMID: 35012612 PMCID: PMC8744265 DOI: 10.1186/s13071-021-05124-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 12/12/2021] [Indexed: 11/10/2022] Open
Abstract
Malaria constitutes one of the largest public health burdens faced by humanity. Malaria control has to be an efficient balance between diagnosis, treatment and vector control strategies. The World Health Organization currently recommends indoor residual spraying and impregnated bed nets as two malaria vector control methods that have shown robust and persistent results against endophilic and anthropophilic mosquito species. The Indian government launched the National Framework for Malaria Elimination in 2016 with the aim to achieve the elimination of malaria in a phased and strategic manner and to sustain a nation-wide malaria-free status by 2030. India is currently in a crucial phase of malaria elimination and novel vector control strategies maybe helpful in dealing with various challenges, such as vector behavioural adaptations and increasing insecticide resistance among the Anopheles populations of India. Ivermectin can be one such new tool as it is the first endectocide to be approved in both animals and humans. Trials of ivermectin have been conducted in endemic areas of Africa with promising results. In this review, we assess available data on ivermectin as an endectocide and propose that this endectocide should be explored as a vector control tool for malaria in India.
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Affiliation(s)
- Sundus Shafat Ahmad
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
| | - Manju Rahi
- Indian Council of Medical Research, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
| | - Poonam Saroha
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
| | - Amit Sharma
- Indian Council of Medical Research (ICMR)–National Institute of Malaria Research, New Delhi, India
- International Centre for Genetic Engineering and Biotechnology, New Delhi, India
- Academy of Scientific and Innovative Research (AcSir), Ghaziabad, India
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15
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Balaska S, Fotakis EA, Chaskopoulou A, Vontas J. Chemical control and insecticide resistance status of sand fly vectors worldwide. PLoS Negl Trop Dis 2021; 15:e0009586. [PMID: 34383751 PMCID: PMC8360369 DOI: 10.1371/journal.pntd.0009586] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Phlebotomine sand flies are prominent vectors of Leishmania parasites that cause leishmaniasis, which comes second to malaria in terms of parasitic causative fatalities globally. In the absence of human vaccines, sand fly chemical-based vector control is a key component of leishmaniasis control efforts. METHODS AND FINDINGS We performed a literature review on the current interventions, primarily, insecticide-based used for sand fly control, as well as the global insecticide resistance (IR) status of the main sand fly vector species. Indoor insecticidal interventions, such as residual spraying and treated bed nets are the most widely deployed, while several alternative control strategies are also used in certain settings and/or are under evaluation. IR has been sporadically detected in sand flies in India and other regions, using non-standardized diagnostic bioassays. Molecular studies are limited to monitoring of known pyrethroid resistance mutations (kdr), which are present at high frequencies in certain regions. CONCLUSIONS As the leishmaniasis burden remains a major problem at a global scale, evidence-based rational use of insecticidal interventions is required to meet public health demands. Standardized bioassays and molecular markers are a prerequisite for this task, albeit are lagging behind. Experiences from other disease vectors underscore the need for the implementation of appropriate IR management (IRM) programs, in the framework of integrated vector management (IVM). The implementation of alternative strategies seems context- and case-specific, with key eco-epidemiological parameters yet to be investigated. New biotechnology-based control approaches might also come into play in the near future to further reinforce sand fly/leishmaniasis control efforts.
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Affiliation(s)
- Sofia Balaska
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Greece
| | - Emmanouil Alexandros Fotakis
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Crop Science, Agricultural University of Athens, Athens, Greece
| | | | - John Vontas
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology Hellas, Heraklion, Greece
- Department of Crop Science, Agricultural University of Athens, Athens, Greece
- * E-mail:
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16
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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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17
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de Souza DK, Thomas R, Bradley J, Leyrat C, Boakye DA, Okebe J. Ivermectin treatment in humans for reducing malaria transmission. Cochrane Database Syst Rev 2021; 6:CD013117. [PMID: 34184757 PMCID: PMC8240090 DOI: 10.1002/14651858.cd013117.pub2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND Malaria is transmitted through the bite of Plasmodium-infected adult female Anopheles mosquitoes. Ivermectin, an anti-parasitic drug, acts by killing mosquitoes that are exposed to the drug while feeding on the blood of people (known as blood feeds) who have ingested the drug. This effect on mosquitoes has been demonstrated by individual randomized trials. This effect has generated interest in using ivermectin as a tool for malaria control. OBJECTIVES To assess the effect of community administration of ivermectin on malaria transmission. SEARCH METHODS We searched the Cochrane Infectious Diseases Group (CIDG) Specialized Register, CENTRAL, MEDLINE, Embase, LILACS, Science Citation index - expanded, the World Health Organization (WHO) International Clinical Trials Registry Platform, ClinicalTrials.gov, and the National Institutes of Health (NIH) RePORTER database to 14 January 2021. We checked the reference lists of included studies for other potentially relevant studies, and contacted researchers working in the field for unpublished and ongoing trials. SELECTION CRITERIA We included cluster-randomized controlled trials (cRCTs) that compared ivermectin, as single or multiple doses, with a control treatment or placebo given to populations living in malaria-endemic areas, in the context of mass drug administration. Primary outcomes were prevalence of malaria parasite infection and incidence of clinical malaria in the community. DATA COLLECTION AND ANALYSIS Two review authors independently extracted data on the number of events and the number of participants in each trial arm at the time of assessment. For rate data, we noted the total time at risk in each trial arm. To assess risk of bias, we used Cochrane's RoB 2 tool for cRCTs. We documented the method of data analysis, any adjustments for clustering or other covariates, and recorded the estimate of the intra-cluster correlation (ICC) coefficient. We re-analysed the trial data provided by the trial authors to adjust for cluster effects. We used a Poisson mixed-effect model with small sample size correction, and a cluster-level analysis using the linear weighted model to adequately adjust for clustering. MAIN RESULTS: We included one cRCT and identified six ongoing trials. The included cRCT examined the incidence of malaria in eight villages in Burkina Faso, randomized to two arms. Both trial arms received a single dose of ivermectin 150 µg/kg to 200 µg/kg, together with a dose of albendazole. The villages in the intervention arm received an additional five doses of ivermectin, once every three weeks. Children were enrolled into an active cohort, in which they were repeatedly screened for malaria infection. The primary outcome was the cumulative incidence of uncomplicated malaria in a cohort of children aged five years and younger, over the 18-week study. We judged the study to be at high risk of bias, as the analysis did not account for clustering or correlation between participants in the same village. The study did not demonstrate an effect of Ivermectin on the cumulative incidence of uncomplicated malaria in the cohort of children over the 18-week study (risk ratio 0.86, 95% confidence interval (CI) 0.62 to 1.17; P = 0.2607; very low-certainty evidence). AUTHORS' CONCLUSIONS We are uncertain whether community administration of ivermectin has an effect on malaria transmission, based on one trial published to date.
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Affiliation(s)
- Dziedzom K de Souza
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Rebecca Thomas
- Department of Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool, UK
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK
| | - Clemence Leyrat
- Medical Statistics Department, London School of Hygiene & Tropical Medicine, London, UK
| | - Daniel A Boakye
- Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana
| | - Joseph Okebe
- Department of International Public Health, Liverpool School of Tropical Medicine, Liverpool, UK
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18
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Rodriguez MH. Residual Malaria: Limitations of Current Vector Control Strategies to Eliminate Transmission in Residual Foci. J Infect Dis 2021; 223:S55-S60. [PMID: 33906220 PMCID: PMC8079132 DOI: 10.1093/infdis/jiaa582] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The transmission of Plasmodium parasites in residual foci is currently a major roadblock for malaria elimination. Human activities and behavior, along with outdoor biting mosquitoes with opportunistic feeding preferences are the main causes of the inefficacy of the main vector control interventions, long lasting insecticide-impregnated nets and insecticide residual spraying. Several strategies to abate or repel outdoor biting mosquito vectors are currently being researched, but the impact of insecticide resistance on the efficacy of these and current indoor-applied insecticides requires further assessment. Understanding the human, ecological and vector factors, determining transmission in residual foci is necessary for the design and implementation of novel control strategies. Vector control alone is insufficient without adequate epidemiological surveillance and prompt treatment of malaria cases, the participation of endemic communities in prevention and control is required. In addition, malaria control programs should optimize their structure and organization, and their coordination with other government sectors.
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Affiliation(s)
- Mario H Rodriguez
- Centro de Investigaciones Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico
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19
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Nicolas P, Kiuru C, Wagah MG, Muturi M, Duthaler U, Hammann F, Maia M, Chaccour C. Potential metabolic resistance mechanisms to ivermectin in Anopheles gambiae: a synergist bioassay study. Parasit Vectors 2021; 14:172. [PMID: 33743783 PMCID: PMC7981804 DOI: 10.1186/s13071-021-04675-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 03/07/2021] [Indexed: 11/10/2022] Open
Abstract
Background Despite remarkable success obtained with current malaria vector control strategies in the last 15 years, additional innovative measures will be needed to achieve the ambitious goals for malaria control set for 2030 by the World Health Organization (WHO). New tools will need to address insecticide resistance and residual transmission as key challenges. Endectocides such as ivermectin are drugs that kill mosquitoes which feed on treated subjects. Mass administration of ivermectin can effectively target outdoor and early biting vectors, complementing the still effective conventional tools. Although this approach has garnered attention, development of ivermectin resistance is a potential pitfall. Herein, we evaluate the potential role of xenobiotic pumps and cytochrome P450 enzymes in protecting mosquitoes against ivermectin by active efflux and metabolic detoxification, respectively. Methods We determined the lethal concentration 50 for ivermectin in colonized Anopheles gambiae; then we used chemical inhibitors and inducers of xenobiotic pumps and cytochrome P450 enzymes in combination with ivermectin to probe the mechanism of ivermectin detoxification. Results Dual inhibition of xenobiotic pumps and cytochromes was found to have a synergistic effect with ivermectin, greatly increasing mosquito mortality. Inhibition of xenobiotic pumps alone had no effect on ivermectin-induced mortality. Induction of xenobiotic pumps and cytochromes may confer partial protection from ivermectin. Conclusion There is a clear pathway for development of ivermectin resistance in malaria vectors. Detoxification mechanisms mediated by cytochrome P450 enzymes are more important than xenobiotic pumps in protecting mosquitoes against ivermectin.![]()
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Affiliation(s)
- Patricia Nicolas
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, 1929, Maputo, Mozambique
| | - Caroline Kiuru
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, 1929, Maputo, Mozambique
| | - Martin G Wagah
- Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 91SA, UK.,Department of Biosciences, KEMRI Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Martha Muturi
- Department of Biosciences, KEMRI Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya
| | - Urs Duthaler
- Division of Clinical Pharmacology and Toxicology, Department of Biomedicine, University and University Hospital Basel, 4056, Basel, Switzerland.,Division of Clinical Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Basel, 4056, Basel, Switzerland
| | - Felix Hammann
- Division of Clinical Pharmacology and Toxicology, Department of Internal Medicine, University Hospital Bern, 3010, Bern, Switzerland
| | - Marta Maia
- Department of Biosciences, KEMRI Wellcome Trust Research Programme, Kilifi, 230-80108, Kenya.,Nuffield Department of Medicine, Centre for Tropical Medicine and Global Health, University of Oxford, Oxford, UK
| | - Carlos Chaccour
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036, Barcelona, Spain. .,Ifakara Health Institute, Ifakara, 67501, United Republic of Tanzania. .,Facultad de Medicina, Universidad de Navarra, 31008, Pamplona, Spain.
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20
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Duthaler U, Weber M, Hofer L, Chaccour C, Maia M, Müller P, Krähenbühl S, Hammann F. The pharmacokinetics and drug-drug interactions of ivermectin in Aedes aegypti mosquitoes. PLoS Pathog 2021; 17:e1009382. [PMID: 33730100 PMCID: PMC7968666 DOI: 10.1371/journal.ppat.1009382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 02/15/2021] [Indexed: 11/29/2022] Open
Abstract
Mosquitoes are vectors of major diseases such as dengue fever and malaria. Mass drug administration of endectocides to humans and livestock is a promising complementary approach to current insecticide-based vector control measures. The aim of this study was to establish an insect model for pharmacokinetic and drug-drug interaction studies to develop sustainable endectocides for vector control. Female Aedes aegypti mosquitoes were fed with human blood containing either ivermectin alone or ivermectin in combination with ketoconazole, rifampicin, ritonavir, or piperonyl butoxide. Drug concentrations were quantified by LC-MS/MS at selected time points post-feeding. Primary pharmacokinetic parameters and extent of drug-drug interactions were calculated by pharmacometric modelling. Lastly, the drug effect of the treatments was examined. The mosquitoes could be dosed with a high precision (%CV: ≤13.4%) over a range of 0.01–1 μg/ml ivermectin without showing saturation (R2: 0.99). The kinetics of ivermectin were characterised by an initial lag phase of 18.5 h (CI90%: 17.0–19.8 h) followed by a slow zero-order elimination rate of 5.5 pg/h (CI90%: 5.1–5.9 pg/h). By contrast, ketoconazole, ritonavir, and piperonyl butoxide were immediately excreted following first order elimination, whereas rifampicin accumulated over days in the mosquitoes. Ritonavir increased the lag phase of ivermectin by 11.4 h (CI90%: 8.7–14.2 h) resulting in an increased exposure (+29%) and an enhanced mosquitocidal effect. In summary, this study shows that the pharmacokinetics of drugs can be investigated and modulated in an Ae. aegypti animal model. This may help in the development of novel vector-control interventions and further our understanding of toxicology in arthropods. Mosquitoes are responsible for the transmission of pathogens, which cause diseases that are of major health significance such as dengue fever and malaria. Preventive strategies involving the use of insecticides, however, have led to the emergence of resistant mosquitoes. Consequently, development of complementary approaches is urgently needed to stop the spread of these pathogens. Our study reports on a pioneering approach to investigate how well drugs are taken up by the mosquitoes and how long they reside in their body. We focused on ivermectin, which is toxic for mosquitoes, and several drugs that interfere with drug metabolising enzymes. We demonstrated that the exposure of drugs can be precisely determined in individual mosquitoes and that drugs interact with each other in the same way as observed in vertebrates. In this regard, we were able to increase the exposure and mosquito toxicity of ivermectin by co-administering ritonavir, a broad-spectrum inhibitor of drug metabolising enzymes. This study establishes Aedes mosquitoes as a new model organism for pharmacokinetic studies. It opens the door for the investigation of novel insecticide strategies and optimisation of lead compounds against mosquitoes.
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Affiliation(s)
- Urs Duthaler
- Division of Clinical Pharmacology & Toxicology, Department of Biomedicine, University and University Hospital Basel, Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
- * E-mail:
| | - Michael Weber
- Division of Clinical Pharmacology & Toxicology, Department of Biomedicine, University and University Hospital Basel, Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Lorenz Hofer
- Swiss Tropical and Public Health institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Carlos Chaccour
- ISGlobal, Hospital Clínic—Universitat de Barcelona, Barcelona, Spain
- Facultad de Medicina, Universidad de Navarra, Pamplona, Spain
- Ifakara Health Institute, Ifakara, United Republic of Tanzania
| | - Marta Maia
- Kenyan Medical Research Institute, Wellcome Trust Research Programme, Department of Biosciences, Kilifi, Kenya
- University of Oxford, Nuffield Department of Medicine, Centre for Global Health and Tropical Medicine, Oxford, United Kingdom
| | - Pie Müller
- Swiss Tropical and Public Health institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Stephan Krähenbühl
- Division of Clinical Pharmacology & Toxicology, Department of Biomedicine, University and University Hospital Basel, Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
| | - Felix Hammann
- Division of Clinical Pharmacology & Toxicology, Department of Biomedicine, University and University Hospital Basel, Basel, Switzerland
- Division of Clinical Pharmacology & Toxicology, Department of Pharmaceutical Sciences, University of Basel, Basel, Switzerland
- Clinical Pharmacology and Toxicology, Department of General Internal Medicine, Inselspital, Bern University Hospital, University of Bern, Switzerland
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21
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Lymphatic filariasis, infection status in Culex quinquefasciatus and Anopheles species after six rounds of mass drug administration in Masasi District, Tanzania. Infect Dis Poverty 2021; 10:20. [PMID: 33648600 PMCID: PMC7919328 DOI: 10.1186/s40249-021-00808-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 02/09/2021] [Indexed: 11/10/2022] Open
Abstract
Background Lymphatic filariasis (LF) elimination program in Tanzania started in 2000 in response to the Global program for the elimination of LF by 2020. Evidence shows a persistent LF transmission despite more than a decade of mass drug administration (MDA). It is advocated that, regular monitoring should be conducted in endemic areas to evaluate the progress towards elimination and detect resurgence of the disease timely. This study was therefore designed to assess the status of Wuchereria bancrofti infection in Culex quinqefasciatus and Anopheles species after six rounds of MDA in Masasi District, South Eastern Tanzania. Methods Mosquitoes were collected between June and July 2019 using Center for Diseases Control (CDC) light traps and gravid traps for indoor and outdoor respectively. The collected mosquitoes were morphologically identified into respective species. Dissections and PCR were carried out to detect W. bancrofti infection. Questionnaire survey and checklist were used to assess vector control interventions and household environment respectively. A Poisson regression model was run to determine the effects of household environment on filarial vector density. Results Overall, 12 452 mosquitoes were collected of which 10 545 (84.7%) were filarial vectors. Of these, Anopheles gambiae complex, An. funestus group and Cx. quinquefasciatus accounted for 0.1%, 0.7% and 99.2% respectively. A total of 365 pools of Cx. quinquefasciatus (each with 20 mosquitoes) and 46 individual samples of Anopheles species were analyzed by PCR. For Cx. quinquefasciatus pools, 33 were positive for W. bancrofti, giving an infection rate of 0.5%, while the 46 samples of Anopheles species were all negative. All 1859 dissected mosquitoes analyzed by microscopy were also negative. Households with modern latrines had less mosquitoes than those with pit latrines [odds ratio (OR) = 0.407, P < 0.05]. Houses with unscreened windows had more mosquitoes as compared to those with screened windows (OR = 2.125, P < 0.05). More than 80% of the participants own bednets while 16.5% had no protection. Conclusions LF low transmission is still ongoing in Masasi District after six rounds of MDA and vector control interventions. The findings also suggest that molecular tools may be essential for xenomonitoring LF transmission during elimination phase. ![]()
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22
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Jones RT, Pretorius E, Ant TH, Bradley J, Last A, Logan JG. The use of islands and cluster-randomized trials to investigate vector control interventions: a case study on the Bijagós archipelago, Guinea-Bissau. Philos Trans R Soc Lond B Biol Sci 2021; 376:20190807. [PMID: 33357055 PMCID: PMC7776941 DOI: 10.1098/rstb.2019.0807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2020] [Indexed: 12/30/2022] Open
Abstract
Vector-borne diseases threaten the health of populations around the world. While key interventions continue to provide protection from vectors, there remains a need to develop and test new vector control tools. Cluster-randomized trials, in which the intervention or control is randomly allocated to clusters, are commonly selected for such evaluations, but their design must carefully consider cluster size and cluster separation, as well as the movement of people and vectors, to ensure sufficient statistical power and avoid contamination of results. Island settings present an opportunity to conduct these studies. Here, we explore the benefits and challenges of conducting intervention studies on islands and introduce the Bijagós archipelago of Guinea-Bissau as a potential study site for interventions intended to control vector-borne diseases. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Robert T. Jones
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
- ARCTEC, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - Elizabeth Pretorius
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - Thomas H. Ant
- Centre for Virus Research, Bearsden Road, Bearsden, Glasgow G61 1QH, UK
| | - John Bradley
- MRC International Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - Anna Last
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
| | - James G. Logan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
- ARCTEC, London School of Hygiene & Tropical Medicine, Keppel Street, Bloomsbury, London WC1E 7HT, UK
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23
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El-Saber Batiha G, Alqahtani A, Ilesanmi OB, Saati AA, El-Mleeh A, Hetta HF, Magdy Beshbishy A. Avermectin Derivatives, Pharmacokinetics, Therapeutic and Toxic Dosages, Mechanism of Action, and Their Biological Effects. Pharmaceuticals (Basel) 2020; 13:E196. [PMID: 32824399 PMCID: PMC7464486 DOI: 10.3390/ph13080196] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/09/2020] [Accepted: 08/13/2020] [Indexed: 12/15/2022] Open
Abstract
Avermectins are a group of drugs that occurs naturally as a product of fermenting Streptomyces avermitilis, an actinomycetes, isolated from the soil. Eight different structures, including ivermectin, abamectin, doramectin, eprinomectin, moxidectin, and selamectin, were isolated and divided into four major components (A1a, A2a, B1a and B2a) and four minor components (A1b, A2b, B1b, and B2b). Avermectins are generally used as a pesticide for the treatment of pests and parasitic worms as a result of their anthelmintic and insecticidal properties. Additionally, they possess anticancer, anti-diabetic, antiviral, antifungal, and are used for treatment of several metabolic disorders. Avermectin generally works by preventing the transmission of electrical impulse in the muscle and nerves of invertebrates, by amplifying the glutamate effects on the invertebrates-specific gated chloride channel. Avermectin has unwanted effects or reactions, especially when administered indiscriminately, which include respiratory failure, hypotension, and coma. The current review examines the mechanism of actions, biosynthesis, safety, pharmacokinetics, biological toxicity and activities of avermectins.
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Affiliation(s)
- Gaber El-Saber Batiha
- Department of Pharmacology and Therapeutics, Faculty of Veterinary Medicine, Damanhour University, Damanhour 22511, Egypt
| | - Ali Alqahtani
- Department of Pharmacology, College of Pharmacy, King Khalid University, Guraiger, Abha 62529, Saudi Arabia;
| | - Omotayo B. Ilesanmi
- Department of Biochemistry, Faculty of Science, Federal University Otuoke, Otuoke 561, Nigeria;
| | - Abdullah A. Saati
- Department of Community Medicine & Pilgrims Healthcare, Faculty of Medicine, Umm Al-Qura University Makkah, Mecca 24382, Saudi Arabia;
| | - Amany El-Mleeh
- Department of Pharmacology, Faculty of Veterinary Medicine, Menoufia University, Shibin Al Kawm 32511, Egypt;
| | - Helal F. Hetta
- Department of Medical Microbiology and Immunology, Faculty of Medicine, Assiut University, Assiut 71515, Egypt;
- Department of Internal Medicine, University of Cincinnati College of Medicine, Cincinnati, OH 45221, USA
| | - Amany Magdy Beshbishy
- National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho, Obihiro 080-8555, Hokkaido, Japan
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