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Hamid-Adiamoh M, Muhammad AK, Assogba BS, Soumare HM, Jadama L, Diallo M, D'Alessandro U, Ousmane Ndiath M, Erhart A, Amambua-Ngwa A. Mosquitocidal effect of ivermectin-treated nettings and sprayed walls on Anopheles gambiae s.s. Sci Rep 2024; 14:12620. [PMID: 38824239 PMCID: PMC11144240 DOI: 10.1038/s41598-024-63389-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: 06/01/2023] [Accepted: 05/28/2024] [Indexed: 06/03/2024] Open
Abstract
Ivermectin (IVM) has been proposed as a new tool for malaria control as it is toxic on vectors feeding on treated humans or cattle. Nevertheless, IVM may have a direct mosquitocidal effect when applied on bed nets or sprayed walls. The potential for IVM application as a new insecticide for long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) was tested in this proof-of-concept study in a laboratory and semi-field environment. Laboratory-reared, insecticide-susceptible Kisumu Anopheles gambiae were exposed to IVM on impregnated netting materials and sprayed plastered- and mud walls using cone bioassays. The results showed a direct mosquitocidal effect of IVM on this mosquito strain as all mosquitoes died by 24 h after exposure to IVM. The effect was slower on the IVM-sprayed walls compared to the treated nettings. Further work to evaluate possibility of IVM as a new insecticide formulation in LLINs and IRS will be required.
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Affiliation(s)
- Majidah Hamid-Adiamoh
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia.
| | - Abdul Khalie Muhammad
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Benoit Sessinou Assogba
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Harouna Massire Soumare
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Lamin Jadama
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Moussa Diallo
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Umberto D'Alessandro
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Mamadou Ousmane Ndiath
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Annette Erhart
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
| | - Alfred Amambua-Ngwa
- Medical Research Council Unit The Gambia at the London School of Hygiene & Tropical Medicine, Banjul, Gambia
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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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Pathak AK, Shiau JC, Freitas RC, Kyle DE. Blood meals from 'dead-end' vertebrate hosts enhance transmission potential of malaria-infected mosquitoes. One Health 2023; 17:100582. [PMID: 38024285 PMCID: PMC10665158 DOI: 10.1016/j.onehlt.2023.100582] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 06/08/2023] [Accepted: 06/08/2023] [Indexed: 12/01/2023] Open
Abstract
Ingestion of an additional blood meal(s) by a hematophagic insect can accelerate development of several vector-borne parasites and pathogens. Most studies, however, offer blood from the same vertebrate host species as the original challenge (for e.g., human for primary and additional blood meals). Here, we show a second blood meal from bovine and canine hosts can also enhance sporozoite migration in Anopheles stephensi mosquitoes infected with the human- and rodent-restricted Plasmodium falciparum and P. berghei, respectively. The extrinsic incubation period (time to sporozoite appearance in salivary glands) showed more consistent reductions with blood from human and bovine donors than canine blood, although the latter's effect may be confounded by the toxicity, albeit non-specific, associated with the anticoagulant used to collect whole blood from donors. The complex patterns of enhancement highlight the limitations of a laboratory system but are nonetheless reminiscent of parasite host-specificity and mosquito adaptations, and the genetic predisposition of An. stephensi for bovine blood. We suggest that in natural settings, a blood meal from any vertebrate host could accentuate the risk of human infections by P. falciparum: targeting vectors that also feed on animals, via endectocides for instance, may reduce the number of malaria-infected mosquitoes and thus directly lower residual transmission. Since endectocides also benefit animal health, our results underscore the utility of the One Health framework, which postulates that human health and well-being is interconnected with that of animals. We posit this framework will be further validated if our observations also apply to other vector-borne diseases which together are responsible for some of the highest rates of morbidity and mortality in socio-economically disadvantaged populations.
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Affiliation(s)
- Ashutosh K. Pathak
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, United States of America
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, GA 30602, United States of America
- Center for the Ecology of Infectious Diseases (CEID), University of Georgia, Athens, GA 30602, United States of America
- The SporoCore, CTEGD, University of Georgia, Athens, GA 30602, United States of America
| | - Justine C. Shiau
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, United States of America
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, GA 30602, United States of America
- Center for the Ecology of Infectious Diseases (CEID), University of Georgia, Athens, GA 30602, United States of America
- The SporoCore, CTEGD, University of Georgia, Athens, GA 30602, United States of America
| | - Rafael C.S. Freitas
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, GA 30602, United States of America
- The SporoCore, CTEGD, University of Georgia, Athens, GA 30602, United States of America
| | - Dennis E. Kyle
- Department of Infectious Diseases, University of Georgia, Athens, GA 30602, United States of America
- Center for Tropical and Emerging Global Diseases (CTEGD), University of Georgia, Athens, GA 30602, United States of America
- The SporoCore, CTEGD, University of Georgia, Athens, GA 30602, United States of America
- Department of Cellular Biology, University of Georgia, Athens, GA 30602, United States of America
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Chakraborty S, Gao S, Allan BF, Smith RL. Effects of cattle on vector-borne disease risk to humans: A systematic review. PLoS Negl Trop Dis 2023; 17:e0011152. [PMID: 38113279 PMCID: PMC10763968 DOI: 10.1371/journal.pntd.0011152] [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: 02/08/2023] [Revised: 01/03/2024] [Accepted: 12/04/2023] [Indexed: 12/21/2023] Open
Abstract
Vector-borne pathogens (VBPs) causing vector-borne diseases (VBDs) can circulate among humans, domestic animals, and wildlife, with cattle in particular serving as an important source of exposure risk to humans. The close associations between humans and cattle can facilitate the transmission of numerous VBPs, impacting public health and economic security. Published studies demonstrate that cattle can influence human exposure risk positively, negatively, or have no effect. There is a critical need to synthesize the information in the scientific literature on this subject, in order to illuminate the various ecological mechanisms that can affect VBP exposure risk in humans. Therefore, the aim of this systematic review was to review the scientific literature, provide a synthesis of the possible effects of cattle on VBP risk to humans, and propose future directions for research. This study was performed according to the PRISMA 2020 extension guidelines for systematic review. After screening 470 peer-reviewed articles published between 1999-2019 using the databases Web of Science Core Collection, PubMed Central, CABI Global Health, and Google Scholar, and utilizing forward and backward search techniques, we identified 127 papers that met inclusion criteria. Results of the systematic review indicate that cattle can be beneficial or harmful to human health with respect to VBDs depending on vector and pathogen ecology and livestock management practices. Cattle can increase risk of exposure to infections spread by tsetse flies and ticks, followed by sandflies and mosquitoes, through a variety of mechanisms. However, cattle can have a protective effect when the vector prefers to feed on cattle instead of humans and when chemical control measures (e.g., acaricides/insecticides), semio-chemicals, and other integrated vector control measures are utilized in the community. We highlight that further research is needed to determine ways in which these mechanisms may be exploited to reduce VBD risk in humans.
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Affiliation(s)
- Sulagna Chakraborty
- Program in Ecology, Evolution & Conservation Biology, University of Illinois Urbana-Champaign; Urbana, Illinois, United Sates of America
| | - Siyu Gao
- School of Social Work, The University of Minnesota, Twin Cities, Minnesota, United Sates of America
| | - Brian. F. Allan
- Program in Ecology, Evolution & Conservation Biology, University of Illinois Urbana-Champaign; Urbana, Illinois, United Sates of America
- Department of Entomology, University of Illinois Urbana-Champaign, Urbana, Illinois, United Sates of America
| | - Rebecca Lee Smith
- Program in Ecology, Evolution & Conservation Biology, University of Illinois Urbana-Champaign; Urbana, Illinois, United Sates of America
- Department of Pathobiology, University of Illinois Urbana-Champaign, Urbana, Illinois, United Sates of America
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Alcântara JA, de Araújo FSA, da Costa Paz A, Alencar RM, de Albuquerque Caldas BY, Godoy RSM, Lacerda MVG, de Melo GC, Monteiro WM, de Souza Sampaio V, Secundino NFC, Duarte APM, Santana RAG, Pimenta PFP. Effect of fluralaner on the biology, survival, and reproductive fitness of the neotropical malaria vector Anopheles aquasalis. Malar J 2023; 22:337. [PMID: 37936198 PMCID: PMC10631211 DOI: 10.1186/s12936-023-04767-0] [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: 02/27/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023] Open
Abstract
BACKGROUND Reducing mosquito abundance or interfering with its ability to support the parasite cycle can help to interrupt malaria in areas of significant risk of malaria transmission. Fluralaner is a safe and effective drug for veterinary use indicated for the treatment against fleas and ticks which acts as an antagonist of chloride ion channels mediated by γ-aminobutyric acid (GABA), preventing the entry of these ions into the postsynaptic neuron, leading to hyperexcitability of the postsynaptic neuron of the central nervous system of arthropods. Fluralaner demonstrated insecticidal activity against different insect species. METHODS The study aimed to evaluate the effects of fluralaner on the biology, survival, and reproductive fitness of Anopheles aquasalis. The following lethal concentrations (LC) were determined for An. aquasalis: LC5 = 0.511 µM; LC25 = 1.625 µM; LC50 = 3.237 µM. RESULTS A significant decrease (P < 0.001) was evident in the number of eggs, larvae, and pupae in the group exposed to a sublethal dose of fluralaner when compared to a control group (without the drug). Using blood from dogs after administration of fluralaner, it was observed that the drug causes 100% mortality in An. aquasalis in less than 24 h after feeding; this effect remains even after 90 days in all samples. DISCUSSION Fluralaner showed the same result for up to 60 days, and after that, there was a slight reduction in its effect, evidenced by a decrease in the percentage of dead females; however, still significant when compared to the control group. CONCLUSION Fluralaner affects the biology and reduction of survival in An. aquasalis in a lasting and prolonged period, and its fecundity with lower dosages, is a strong candidate for controlling disease vectors.
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Affiliation(s)
- João Arthur Alcântara
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Francys Sayara Andrade de Araújo
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Andréia da Costa Paz
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Rodrigo Maciel Alencar
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | | | - Raquel Soares Maia Godoy
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Marcus Vinicius Guimarães Lacerda
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto Leônidas e Maria Deane - Fundação Oswaldo Cruz - (ILMD - Fiocruz Amazônia), Manaus, Brazil
- University of Texas Medical Branch (UTMB), Galveston, USA
| | - Gisely Cardoso de Melo
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Wuelton Marcelo Monteiro
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Vanderson de Souza Sampaio
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
| | - Nágila Francinete Costa Secundino
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Ana Paula Marques Duarte
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil
| | - Rosa Amélia Gonçalves Santana
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil
- Instituto Leônidas e Maria Deane - Fundação Oswaldo Cruz - (ILMD - Fiocruz Amazônia), Manaus, Brazil
| | - Paulo Filemon Paolucci Pimenta
- Programa de Pós-graduação em Medicina Tropical-Universidade do Estado do Amazonas/Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (PPGM-UEA/FMT-HVD), Manaus, Brazil.
- Departamento de Ensino e Pesquisa-Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (DENPE/FMT-HVD), Manaus, Brazil.
- Programa de Pós-Graduação Em Ciências da Saúde, FIOCRUZ-Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
- Instituto René Rachou-Fundação Oswaldo Cruz-(IRR-Fiocruz Minas), Belo Horizonte, Brazil.
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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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7
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Pooda SH, Moiroux N, Porciani A, Courjaud AL, Roberge C, Gaudriault G, Sidibé I, Belem AMG, Rayaissé JB, Dabiré RK, Mouline K. Proof-of-concept study for a long-acting formulation of ivermectin injected in cattle as a complementary malaria vector control tool. Parasit Vectors 2023; 16:66. [PMID: 36788608 PMCID: PMC9926456 DOI: 10.1186/s13071-022-05621-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Accepted: 12/15/2022] [Indexed: 02/16/2023] Open
Abstract
BACKGROUND Domesticated animals play a role in maintaining residual transmission of Plasmodium parasites of humans, by offering alternative blood meal sources for malaria vectors to survive on. However, the blood of animals treated with veterinary formulations of the anti-helminthic drug ivermectin can have an insecticidal effect on adult malaria vector mosquitoes. This study therefore assessed the effects of treating cattle with long-acting injectable formulations of ivermectin on the survival of an important malaria vector species, to determine whether it has potential as a complementary vector control measure. METHODS Eight head of a local breed of cattle were randomly assigned to either one of two treatment arms (2 × 2 cattle injected with one of two long-acting formulations of ivermectin with the BEPO® technology at the therapeutic dose of 1.2 mg/kg), or one of two control arms (2 × 2 cattle injected with the vehicles of the formulations). The lethality of the formulations was evaluated on 3-5-day-old Anopheles coluzzii mosquitoes through direct skin-feeding assays, from 1 to 210 days after treatment. The efficacy of each formulation was evaluated and compared using Cox proportional hazards survival models, Kaplan-Meier survival estimates, and log-logistic regression on cumulative mortality. RESULTS Both formulations released mosquitocidal concentrations of ivermectin until 210 days post-treatment (hazard ratio > 1). The treatments significantly reduced mosquito survival, with average median survival time of 4-5 days post-feeding. The lethal concentrations to kill 50% of the Anopheles (LC50) before they became infectious (10 days after an infectious blood meal) were maintained for 210 days post-injection for both formulations. CONCLUSIONS This long-lasting formulation of ivermectin injected in cattle could complement insecticide-treated nets by suppressing field populations of zoophagic mosquitoes that are responsible, at least in part, for residual malaria transmission. The impact of this approach will of course depend on the field epidemiological context. Complementary studies will be necessary to characterize ivermectin withdrawal times and potential environmental toxicity.
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Affiliation(s)
- Sié Hermann Pooda
- Université de Dédougou, Dedougou, Burkina Faso
- Centre International de Recherche et Développement pour l’Élevage en zones Sub-humides, Bobo-Dioulasso, Burkina Faso
- Insectarium de Bobo Dioulasso – Campagne d’éradication de la mouche Tsé Tsé et des Trypanosomoses, Bobo-Dioulasso, Burkina Faso
- Université Nazi Boni, Bobo-Dioulasso, Burkina Faso
| | - Nicolas Moiroux
- MIVEGEC, Université de Montpellier-CNRS-IRD, Montpellier, France
| | | | | | | | | | - Issa Sidibé
- Insectarium de Bobo Dioulasso – Campagne d’éradication de la mouche Tsé Tsé et des Trypanosomoses, Bobo-Dioulasso, Burkina Faso
| | | | - Jean-Baptiste Rayaissé
- Centre International de Recherche et Développement pour l’Élevage en zones Sub-humides, Bobo-Dioulasso, Burkina Faso
| | - Roch K. Dabiré
- Institut de Recherche en Sciences de la Santé, Bobo Dioulasso, Burkina Faso
| | - Karine Mouline
- MIVEGEC, Université de Montpellier-CNRS-IRD, Montpellier, France
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8
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Dias ACA, Teixeira AV, Lima Bezerra F, Andriolo A, Silva ADA. Sugar Bait Composition Containing Ivermectin Affect Engorgement and Mortality of the Mosquito Aedes aegypti (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2023; 60:159-164. [PMID: 36440696 DOI: 10.1093/jme/tjac181] [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: 05/06/2022] [Indexed: 06/16/2023]
Abstract
Toxins and attractants have been studied and used in sugar baits for mosquitoes. However, little importance has been given to the combination of sugar concentration, bait composition, and their relationship with mosquito engorgement and mortality. Therefore, the present study evaluated the effects of three concentrations of sucrose on baits with and without an attractant (concentrated guava juice), on engorgement and mortality rates of adult Aedes aegypti (Linnaeus, Diptera: Culicidae). Toxic sugar baits (TSB) and attractant toxic sugar baits (ATSB) containing 10, 50, and 70% sucrose and 100 ppm ivermectin (IVM) were prepared to assess engorgement and mortality rates. Subsequently, different concentrations of IVM (0.312-100 ppm) in TSB and ATSB were prepared with sucrose concentrations of 10 and 70% to determine the lethal concentrations (LC50 and LC90) values. Engorgement on the baits was observed under a stereomicroscope, and mortality was followed up to 48 h after feeding. In general, more mosquitoes engorged on TSB regardless of the sugar concentration, while higher concentrations of sugar in ATSBs resulted in higher numbers of mosquitoes engorging. A large increase in the LC90 of IVM was observed for females feeding on ATSBs and TSBs with 70% sucrose relative to those feeding on baits with lower sugar concentrations. No such effect was observed for males.
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Affiliation(s)
- Alyne Cunha Alves Dias
- Programa de Pós-Graduação em Biologia Experimental, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
| | - Aurea Vieira Teixeira
- Programa de Pós-Graduação em Biologia Experimental, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
| | - Flaviana Lima Bezerra
- Laboratório de Bioecologia de Insetos, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
| | - Aline Andriolo
- Programa de Pós-Graduação em Conservação e uso de Recursos Naturais, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
| | - Alexandre de A Silva
- Programa de Pós-Graduação em Biologia Experimental, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
- Laboratório de Bioecologia de Insetos, Universidade Federal de Rondônia, Porto Velho, RO, Brasil
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9
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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: 3] [Impact Index Per Article: 3.0] [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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10
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Ikerionwu C, Ugwuishiwu C, Okpala I, James I, Okoronkwo M, Nnadi C, Orji U, Ebem D, Ike A. Application of machine and deep learning algorithms in optical microscopic detection of Plasmodium: A malaria diagnostic tool for the future. Photodiagnosis Photodyn Ther 2022; 40:103198. [PMID: 36379305 DOI: 10.1016/j.pdpdt.2022.103198] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 11/14/2022]
Abstract
Machine and deep learning techniques are prevalent in the medical discipline due to their high level of accuracy in disease diagnosis. One such disease is malaria caused by Plasmodium falciparum and transmitted by the female anopheles mosquito. According to the World Health Organisation (WHO), millions of people are infected annually, leading to inevitable deaths in the infected population. Statistical records show that early detection of malaria parasites could prevent deaths and machine learning (ML) has proved helpful in the early detection of malarial parasites. Human error is identified to be a major cause of inaccurate diagnostics in the traditional microscopy malaria diagnosis method. Therefore, the method would be more reliable if human expert dependency is restricted or entirely removed, and thus, the motivation of this paper. This study presents a systematic review to understand the prevalent machine learning algorithms applied to a low-cost, portable optical microscope in the automation of blood film interpretation for malaria parasite detection. Peer-reviewed papers were downloaded from selected reputable databases eg. Elsevier, IEEExplore, Pubmed, Scopus, Web of Science, etc. The extant literature suggests that convolutional neural network (CNN) and its variants (deep learning) account for 41.9% of the microscopy malaria diagnosis using machine learning with a prediction accuracy of 99.23%. Thus, the findings suggest that early detection of the malaria parasite has improved through the application of CNN and other ML algorithms on microscopic malaria parasite detection.
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Affiliation(s)
- Charles Ikerionwu
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Software Engineering, Federal University of Technology, Owerri, Imo State, Nigeria
| | - Chikodili Ugwuishiwu
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Computer Science, University of Nigeria, Nsukka, Enugu State, Nigeria.
| | - Izunna Okpala
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Information Technology, University of Cincinnati, USA
| | - Idara James
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Computer Science, Akwa Ibom State University, Nigeria
| | - Matthew Okoronkwo
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Computer Science, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Charles Nnadi
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Deprtment of Pharmaceutical and Medicinal Chemistry, Faculty of Pharmaceutical Sciences, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Ugochukwu Orji
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Computer Science, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Deborah Ebem
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Computer Science, University of Nigeria, Nsukka, Enugu State, Nigeria
| | - Anthony Ike
- Machine Learning on Disease Diagnosis Research Group, Nigeria; Department of Microbiology, University of Nigeria, Nsukka, Enugu State, Nigeria
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11
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Dreyer SM, Vaughan JA. Survival and Fecundity of Anopheles stephensi and Anopheles albimanus Mosquitoes (Diptera: Culicidae) After Ingesting Bovine Blood Containing Various Veterinary Systemic Parasiticides. JOURNAL OF MEDICAL ENTOMOLOGY 2022; 59:1700-1709. [PMID: 35934895 PMCID: PMC9473655 DOI: 10.1093/jme/tjac103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Indexed: 05/13/2023]
Abstract
Systemic parasiticides in livestock can control zoophilic malaria vectors that contribute to residual malaria transmission. Membrane feeding techniques were used to screen seven systemic parasiticidic drugs currently in veterinary use for livestock and dogs. Drugs were tested in two laboratory strains of zoophilic Anopheles - A. stephensi (South Asian vector) and A. albimanus (Central American vector). To assess the relative potentials of these drugs, the resultant LC-50 for each drug was compared with what is known about the pharmacokinetic of the drug. Drugs with LC-50 values below the reported maximum plasma concentration of treated animals were considered as showing the most promise for use in the field. Ivermectin and fipronil showed the greatest promise for use in cattle against A. stephensi. Fipronil showed the greatest promise for use in cattle against A. albimanus. Both fluralaner and afoxolaner were highly effective against both mosquito species but pharmacokinetic data for these drugs in cattle are lacking. Eprinomectin, moxidectin and abamectin showed marginal to no promise for either mosquito species. At sublethal doses, ivermectin, fipronil, and afoxolaner (but not fluralaner) significantly reduced the larval production of surviving A. stephensi and A. albimanus. Further testing of candidate systemic parasiticides, including their product formulations, in livestock against field-collected populations of Anopheles is the next logical step toward full implementation of this strategy to manage zoophilic vectors.
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Affiliation(s)
- Staci M Dreyer
- Department of Biology, University of North Dakota, Grand Forks, ND, USA
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12
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Velho MC, Fontana de Andrade D, Beck RCR. Ivermectin: recent approaches in the design of novel veterinary and human medicines. Pharm Dev Technol 2022; 27:865-880. [PMID: 36062978 DOI: 10.1080/10837450.2022.2121840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
Ivermectin (IVM) is a drug widely used in veterinary and human medicine for the management of parasitic diseases. Its repositioning potential has been recently considered for the treatment of different diseases, such as cancer and viral infections. However, IVM faces some limitations to its formulations due to its low water solubility and bioavailability, along with reports of drug resistance. In this sense, novel technological approaches have been explored to optimize its formulations and/or to develop innovative medicines. Therefore, this review discusses the strategies proposed in the last decade to improve the safety and efficacy of IVM and to explore its novel therapeutic applications. Among these technologies, the use of micro/nano-drug delivery systems is the most used approach, followed by long-acting formulations. In general, the development of these novel formulations seems to run side by side in veterinary and human health, showing a shared interface between the two areas. Although the technologies proposed indicate a promising future in the development of innovative dosage forms containing IVM, its safety and therapeutic targets must be further evaluated. Overall, these approaches comprise tailoring drug delivery profiles, decreasing the risks of developing drug resistance, and supporting the application of IVM for reaching different therapeutic targets.
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Affiliation(s)
- Maiara Callegaro Velho
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.,Laboratório de Nanocarreadores e Impressão 3D em Tecnologia Farmacêutica (Nano3D), Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre
| | - Diego Fontana de Andrade
- Departamento de Produção e Controle de Matéria-Prima, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.,Laboratório de Nanocarreadores e Impressão 3D em Tecnologia Farmacêutica (Nano3D), Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre
| | - Ruy Carlos Ruver Beck
- Programa de Pós-Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.,Departamento de Produção e Controle de Medicamentos, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, Rio Grande do Sul, Brazil.,Laboratório de Nanocarreadores e Impressão 3D em Tecnologia Farmacêutica (Nano3D), Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre
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13
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Onyeaka H, Tamasiga P, Agbara JO, Mokgwathi OA, Uwishema O. The use of Ivermectin for the treatment of COVID-19: Panacea or enigma? CLINICAL EPIDEMIOLOGY AND GLOBAL HEALTH 2022; 16:101074. [PMID: 35694631 PMCID: PMC9174099 DOI: 10.1016/j.cegh.2022.101074] [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: 03/02/2022] [Revised: 05/18/2022] [Accepted: 05/22/2022] [Indexed: 11/22/2022] Open
Abstract
The outbreak of SARS-CoV-2 pandemic has triggered unprecedented social, economic and health challenges. To control and reduce the infection rate, countries employed non-pharmaceutical measures such as social distancing, isolation, quarantine, and the use of masks, hand and surface sanitisation. Since 2021 a global race for COVID-19 vaccination ensued, mainly due to a lack of equitable vaccine production and distribution. To date, no treatments have been demonstrated to cure COVID-19. The scientific World is now considering the potential use of Ivermectin as a prophylactic and treatment for COVID-19. Against this background, the objective of this study is to review the literature to demystify the enigma or panacea in the use of Ivermectin. This paper intends to investigate literature which supports the existence or shows the nonexistence of a causal link between Ivermectin, COVID-19 mortality and recovery. There are inconsistent results on the effectiveness of Ivermectin in the treatment of COVID-19 patients. Some studies have asserted that in a bid to slow down the transmission of COVID-19, ivermectin can be used to inhibit the in vitro replication of SARS-CoV-2. The pre-existing health system burdens can be alleviated as patients treated prophylactically would reduce hospital admissions and stem the spread of COVID-19. On a global scale, Ivermectin is currently used by about 28% of the world's population, and its adoption is presently about 44% of countries. However, the full administration of this drug would require further tests to establish its clinical effectiveness and efficacy.
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Affiliation(s)
- Helen Onyeaka
- School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | | | - Joy O Agbara
- Department of Obstetrics and Gynaecology, College of Medicine, Lagos State University, Lagos, Nigeria
| | | | - Olivier Uwishema
- Oli Health Magazine Organization, Research and Education, Kigali, Rwanda.,Clinton Global Initiative University, New York, NY, USA.,Faculty of Medicine, Karadeniz Technical University, Trabzon, Turkey
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14
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Dreyer SM, Morin KJ, Magaña M, Pott M, Leiva D, Achee NL, Grieco JP, Vaughan JA. Oral susceptibility to ivermectin is over fifty times greater in a wild population of Anopheles albimanus mosquitoes from Belize than the STECLA laboratory reference strain of this mosquito. Malar J 2022; 21:72. [PMID: 35246147 PMCID: PMC8896111 DOI: 10.1186/s12936-022-04092-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Accepted: 02/16/2022] [Indexed: 12/12/2022] Open
Abstract
Background The STECLA strain of Anopheles albimanus has been in continuous colony for many years and is the reference strain on which genomic studies for the species are based. Recently, the STECLA strain was demonstrated to be much less susceptible to ivermectin ingested in a blood meal (4-day LC50 of 1468 ng/ml) than all other Anopheles species tested to-date (LC50 values range from 7 to 56 ng/ml). The ability of An. albimanus to survive ingestion of ivermectin at concentrations far beyond that typically found in the blood of ivermectin-treated people or livestock (i.e., 30–70 ng/ml) could invalidate the use of ivermectin as a malaria vector control strategy in areas where An. albimanus is a primary vector. Methods To investigate this, host-seeking An. albimanus were captured in northern Belize and used in membrane feeding bioassays of ivermectin, employing the same methods as described earlier with the STECLA strain. Results Field-collected An. albimanus in Belize were 55 times more susceptible to ingested ivermectin than were the STECLA reference strain. Oral susceptibility to ivermectin in wild An. albimanus from Belize (4-day LC50 of 26 ng/ml) was equivalent to that of other Anopheles species tested. Conclusions Contrary to initial assessments using a highly inbred strain of mosquito, laboratory studies using a field population indicate that ivermectin treatment of livestock could reduce An. albimanus populations in areas of Central America and the Caribbean where malaria transmission may occur. Toxicity screening of ivermectin and other systemic parasiticides for malaria control should examine wild populations of the vector species being targeted.
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Affiliation(s)
| | | | - Marla Magaña
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Marie Pott
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Donovan Leiva
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Nicole L Achee
- Belize Vector and Ecology Center, Orange Walk Town, Belize.,University of Notre Dame, South Bend, IN, 46556, USA
| | - John P Grieco
- Belize Vector and Ecology Center, Orange Walk Town, Belize.,University of Notre Dame, South Bend, IN, 46556, USA
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15
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Atta AH, Atta SA, Nasr SM, Mouneir SM. Current perspective on veterinary drug and chemical residues in food of animal origin. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:15282-15302. [PMID: 34981398 DOI: 10.1007/s11356-021-18239-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 12/16/2021] [Indexed: 06/14/2023]
Abstract
The marked increase in the demand for animal protein of high quality necessitates protecting animals from infectious diseases. This requires increasing the use of veterinary therapeutics. The overuse and misuse of veterinary products can cause a risk to human health either as short-term or long-term health problems. However, the biggest problem is the emergence of resistant strains of bacteria or parasites. This is in addition to economic losses due to the discarding of polluted milk or condemnation of affected carcasses. This paper discusses three key points: possible sources of drug and chemical residues, human health problems, and the possible method of control and prevention of veterinary drug residues in animal products.
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Affiliation(s)
- Attia H Atta
- Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
| | - Shimaa A Atta
- Immunology Department, Theodor Bilharz Research Institute, Giza, 12411, Egypt
| | - Soad M Nasr
- Department of Parasitology & Animal Diseases, National Research Centre, 33 Bohouth St., Dokki, Giza, 12622, Egypt
| | - Samar M Mouneir
- Department of Pharmacology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt
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16
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Faraji-Fard P, Ahmadi-Angali K, Behbahani A. Species Variety of the Calf and Human-Attracted Mosquitoes in Southwest Iran. J Arthropod Borne Dis 2022; 15:162-170. [PMID: 35111854 PMCID: PMC8782744 DOI: 10.18502/jad.v15i2.7485] [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: 10/21/2017] [Accepted: 04/14/2021] [Indexed: 11/29/2022] Open
Abstract
Background: Any mosquito control methods requires precise information about population dynamics, variety, biology and mosquito habitat. This research assessed Culicid mosquitoes’ attraction to a human host and a calf to better understand their behavior. Methods: Adult mosquitoes were sampled in 22 weeks in southwestern Iran’s Nur Ali Village from May to October 2015. The mosquitoes were drawn to the person and calf as bait, while the unbaited trap was also used. A substantial statistical difference between attracted mosquitoes to the hosts was determined in the T-test. Results: Within 22 weeks, 29821 mosquitoes were captured. Only 9% were collected from the human baited net trap, 89.1% from the calf baited net trap, and 1.9% from the unbaited net trap. The number of collected female mosquitoes was statistically significantly higher using the calf baited net trap of the total mosquitoes, 916 were randomly identified at the species level by local identification keys. Of these, 63 were Anopheles stephensi (human: 16%, calf: 75% and unbaited: 9%), 83 An. pulcherrimus (human: 27%, calf: 60% and unbaited: 13%), 118 Aedes caspius (human: 24%, calf: 69% and unbaited: 7%), 493 Culex tritaeniorhynchus (human: 52%, calf: 37% and unbaited: 11%), 153 Cx. quinquefasciatus (human: 44%, calf: 47% and unbaited: 9%), and 6 Cx. theileri (human: 33%, calf: 50% and unbaited: 17%). Conclusion: The obtained results here provide useful insights into the mosquito population and the possibility of using this information as an essential part of integrated vector management regarding the reemergence of malaria or other mosquito-borne.
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Affiliation(s)
- Parvaneh Faraji-Fard
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Kambiz Ahmadi-Angali
- Department of Biostatistics, Faculty of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
| | - Abdolamir Behbahani
- Infectious and Tropical Diseases Research Center, Health Research Institute, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran.,Department of Medical Entomology, Faculty of Public Health, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran
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17
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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] [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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Fikrig K, Harrington LC. Understanding and interpreting mosquito blood feeding studies: the case of Aedes albopictus. Trends Parasitol 2021; 37:959-975. [PMID: 34497032 DOI: 10.1016/j.pt.2021.07.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 07/23/2021] [Accepted: 07/23/2021] [Indexed: 12/31/2022]
Abstract
Blood feeding is a fundamental mosquito behavior with consequences for pathogen transmission and control. Feeding behavior can be studied through two lenses - patterns and preference. Feeding patterns are assessed via blood meal analyses, reflecting mosquito-host associations influenced by environmental and biological parameters. Bias can profoundly impact results, and we provide recommendations for mitigating these effects. We also outline design choices for host preference research, which can take many forms, and highlight their respective (dis)advantages for preference measurement. Finally, Aedes albopictus serves as a case study for how to apply these lessons to interpret data and understand feeding biology. We illustrate how assumptions and incomplete evidence can lead to inconsistent interpretations by reviewing Ae. albopictus feeding studies alongside prevalent narratives about perceived behavior.
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Affiliation(s)
- Kara Fikrig
- Department of Entomology, Cornell University, Ithaca, NY, USA.
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19
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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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20
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Makhanthisa TI, Braack L, Lutermann H. The effect of cattle-administered ivermectin and fipronil on the mortality and fecundity of Anopheles arabiensis Patton. Parasit Vectors 2021; 14:349. [PMID: 34215295 PMCID: PMC8254271 DOI: 10.1186/s13071-021-04846-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/11/2021] [Indexed: 11/10/2022] Open
Abstract
Background Malaria control primarily depends on two vector control strategies: indoor residual spraying (IRS) and long-lasting insecticide-treated nets (LLINs). Both IRS and LLIN target indoor-biting mosquitoes. However, some of the most important malaria vectors have developed resistance against the chemical compounds used in IRS and LLINs. Insecticide-induced behavioural changes in vectors, such as increased outdoor feeding on cattle and other animals, also limit the effectiveness of these strategies. Novel vector control strategies must therefore be found to complement IRS and LLINs. A promising tool is the use of cattle-applied endectocides. Endectocides are broad-spectrum systemic drugs that are effective against a range of internal nematodes parasites and blood-feeding arthropods. The aim of this study was to investigate the effect of two endectocide drugs, injectable ivermectin and topical fipronil, on the survival and fecundity of zoophilic Anopheles arabiensis. Methods Laboratory-reared mosquitoes were allowed to feed on cattle treated with either injectable ivermectin (0.2 mg/kg), topical fipronil (1.0 mg/kg) or saline (control) on days 0, 1, 4, 7, 13, 21 and 25 post-treatment, and mortality and egg production were recorded daily. Results Compared to controls, the mortality of An. arabiensis increased by 3.52- and 2.43-fold with injectable ivermectin and topical fipronil, respectively. The overall fecundity of mosquitoes that fed on both ivermectin- and fipronil-treated cattle was significantly reduced by up to 90 and 60%, respectively, compared to the control group. The effects of both drugs attenuated over a period of 3 weeks. Injectable ivermectin was more effective than topical fipronil and increased mosquito mortality by a risk factor of 1.51 higher than fipronil. Similarly, both drugs significantly reduced the fecundity of An. arabiensis. Conclusions This study demonstrates that injectable ivermectin and topical fipronil are able to suppress An. arabiensis density and could help to reduce outdoor malaria transmission. Data from the present study as well as from other similar studies suggest that current-generation endectocides have a limited duration of action and are expensive. However, new-generation, sustained-release formulations of ivermectin have a multi-week, high mortality impact on vector populations, thus holding promise of an effective reduction of outdoor malaria transmission. Graphical abstract ![]()
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Affiliation(s)
- Takalani I Makhanthisa
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa.,UP Institute for Sustainable Malaria Control, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa
| | - Leo Braack
- UP Institute for Sustainable Malaria Control, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.,Faculty of Tropical Medicine, Malaria Consortium, Mahidol University, Bangkok, Thailand
| | - Heike Lutermann
- Mammal Research Institute, Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa.
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21
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Jagannathan SV, Manemann EM, Rowe SE, Callender MC, Soto W. Marine Actinomycetes, New Sources of Biotechnological Products. Mar Drugs 2021; 19:365. [PMID: 34201951 PMCID: PMC8304352 DOI: 10.3390/md19070365] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2021] [Revised: 06/14/2021] [Accepted: 06/21/2021] [Indexed: 02/07/2023] Open
Abstract
The Actinomycetales order is one of great genetic and functional diversity, including diversity in the production of secondary metabolites which have uses in medical, environmental rehabilitation, and industrial applications. Secondary metabolites produced by actinomycete species are an abundant source of antibiotics, antitumor agents, anthelmintics, and antifungals. These actinomycete-derived medicines are in circulation as current treatments, but actinomycetes are also being explored as potential sources of new compounds to combat multidrug resistance in pathogenic bacteria. Actinomycetes as a potential to solve environmental concerns is another area of recent investigation, particularly their utility in the bioremediation of pesticides, toxic metals, radioactive wastes, and biofouling. Other applications include biofuels, detergents, and food preservatives/additives. Exploring other unique properties of actinomycetes will allow for a deeper understanding of this interesting taxonomic group. Combined with genetic engineering, microbial experimental evolution, and other enhancement techniques, it is reasonable to assume that the use of marine actinomycetes will continue to increase. Novel products will begin to be developed for diverse applied research purposes, including zymology and enology. This paper outlines the current knowledge of actinomycete usage in applied research, focusing on marine isolates and providing direction for future research.
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Affiliation(s)
| | | | | | | | - William Soto
- Department of Biology, College of William & Mary, Williamsburg, VA 23185, USA; (S.V.J.); (E.M.M.); (S.E.R.); (M.C.C.)
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22
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Okumu F, Finda M. Key Characteristics of Residual Malaria Transmission in Two Districts in South-Eastern Tanzania-Implications for Improved Control. J Infect Dis 2021; 223:S143-S154. [PMID: 33906218 PMCID: PMC8079133 DOI: 10.1093/infdis/jiaa653] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
After 2 decades of using insecticide-treated nets (ITNs) and improved case management, malaria burden in the historically-holoendemic Kilombero valley in Tanzania has significantly declined. We review key characteristics of the residual transmission and recommend options for improvement. Transmission has declined by >10-fold since 2000 but remains heterogeneous over small distances. Following the crash of Anopheles gambiae, which coincided with ITN scale-up around 2005-2012, Anopheles funestus now dominates malaria transmission. While most infections still occur indoors, substantial biting happens outdoors and before bed-time. There is widespread resistance to pyrethroids and carbamates; An. funestus being particularly strongly-resistant. In short and medium-term, these challenges could be addressed using high-quality indoor residual spraying with nonpyrethroids, or ITNs incorporating synergists. Supplementary tools, eg, spatial-repellents may expand protection outdoors. However, sustainable control requires resilience-building approaches, particularly improved housing and larval-source management to suppress mosquitoes, stronger health systems guaranteeing case-detection and treatment, greater community-engagement and expanded health education.
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Affiliation(s)
- Fredros Okumu
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, University of the Witwatersrand, Johannesburg, Republic of South Africa
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
- School of Life Science and Bioengineering, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Marceline Finda
- Environmental Health and Ecological Sciences, Ifakara Health Institute, Ifakara, Tanzania
- School of Public Health, University of the Witwatersrand, Johannesburg, Republic of South Africa
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23
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Degefa T, Githeko AK, Lee MC, Yan G, Yewhalaw D. Patterns of human exposure to early evening and outdoor biting mosquitoes and residual malaria transmission in Ethiopia. Acta Trop 2021; 216:105837. [PMID: 33485868 DOI: 10.1016/j.actatropica.2021.105837] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 01/10/2021] [Accepted: 01/12/2021] [Indexed: 10/22/2022]
Abstract
Ethiopia has shown a notable progress in reducing malaria burden over the past decade, mainly due to the scaleup of vector control interventions such as long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). Based on the progress, the country has set goals to eliminate malaria by 2030. However, residual malaria transmission due to early evening and outdoor biting vectors could pose a challenge to malaria elimination efforts. This study assessed vector behavior, patterns of human exposure to vector bites and residual malaria transmission in southwestern Ethiopia. Anopheles mosquitoes were collected monthly from January to December 2018 using human landing catches (HLCs), human-baited double net traps, CDC light traps and pyrethrum spray catches. Human behavior data were collected using questionnaire to estimate the magnitude of human exposure to mosquito bites occurring indoors and outdoors at various times of the night. Enzyme-linked immunosorbent assay (ELISA) was used to determine mosquito blood meal sources and sporozoite infections. A total of 2,038 female Anopheles mosquitoes comprising Anopheles arabiensis (30.8%), An. pharoensis (40.5%), An. coustani (28.1%), An. squamosus (0.3%) and An. funestus group (0.2%) were collected. Anopheles arabiensis and An. pharoensis were 2.4 and 2.5 times more likely to seek hosts outdoors than indoors, respectively. However, 66% of human exposure to An. arabiensis and 39% of exposure to An. pharoensis bites occurred indoors for LLIN non-users. For LLIN users, 75% of residual exposure to An. arabiensis bites occurred outdoors while 23% occurred indoors before bed time. Likewise, 84% of residual exposure to An. pharoensis bites occurred outdoors while 15% occurred indoors before people retired to bed. Anopheles arabiensis and An. pharoensis were 4.1 and 4.8 times more likely to feed on bovine than humans, respectively. Based on the HLC, an estimated indoor and outdoor EIR of An. arabiensis was 6.2 and 1.4 infective bites/person/year, respectively, whereas An. pharoensis had an estimated outdoor EIR of 3.0 infective bites/person/year. In conclusion, An. arabiensis and An. pharoensis showed exophagic and zoophagic behavior. Human exposure to An. arabiensis bites occurred mostly indoors for LLIN non-users, while most of the exposure to both An. arabiensis and An. pharoensis bites occurred outdoors for LLIN users. Malaria transmission by An. arabiensis occurred both indoors and outdoors, whereas An. pharoensis contributed exclusively to outdoor transmission. Additional control tools targeting early-evening and outdoor biting malaria vectors are required to complement the current control interventions to control residual transmission and ultimately achieve malaria elimination.
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24
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Khaligh FG, Jafari A, Silivanova E, Levchenko M, Rahimi B, Gholizadeh S. Endectocides as a complementary intervention in the malaria control program: a systematic review. Syst Rev 2021; 10:30. [PMID: 33455581 PMCID: PMC7812718 DOI: 10.1186/s13643-021-01578-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/02/2021] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Malaria is the most common vector-borne disease transmitted to humans by Anopheles mosquitoes. Endectocides and especially ivermectin will be available as a vector control tool soon. The current review could be valuable for trial design and clinical studies to control malaria transmission. METHODS PubMed/MEDLINE, Scopus, Web of Science, and Science Direct were searched for original English published papers on ("Malaria chemical control" OR "Malaria elimination" OR "Anopheles vector control" OR "Malaria zooprophylaxis") AND ("Systemic insecticides" OR "Endectocides" OR "Ivermectin"). The last search was from 19 June 2019 to 31 December 2019. It was updated on 17 November 2020. Two reviewers (SG and FGK) independently reviewed abstracts and full-text articles. Data were extracted by one person and checked by another. As meta-analyses were not possible, a qualitative summary of results was performed. RESULTS Thirty-six published papers have used systemic insecticides/endectocides for mosquito control. Most of the studies (56.75%) were done on Anopheles gambiae complex species on doses from 150 μg/kg to 400 μg/kg in several studies. Target hosts for employing systemic insecticides/drugs were animals (44.2%, including rabbit, cattle, pig, and livestock) and humans (32.35%). CONCLUSIONS Laboratory and field studies have highlighted the potential of endectocides in malaria control. Ivermectin and other endectocides could soon serve as novel malaria transmission control tools by reducing the longevity of Anopheles mosquitoes that feed on treated hosts, potentially decreasing Plasmodium parasite transmission when used as mass drug administration (MDA).
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Affiliation(s)
- Fereshteh Ghahvechi Khaligh
- Social Determinants of Health Research Center, Clinical Research Institute, Urmia University of Medical Sciences, Urmia, Iran.,Medical Entomology Department, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran
| | - Abbas Jafari
- Department of Clinical Toxicology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran.,Cellular and Molecular Research Center, Research Institute on Cellular and Molecular Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Elena Silivanova
- All-Russian Scientific Research Institute of Veterinary Entomology and Arachnology, Branch of Federal State Institution Federal Research Centre Tyumen Scientific Centre, Siberian Branch of the Russian Academy of Sciences (ASRIVEA - Branch of Tyumen Scientific Centre SB RAS), Institutskaya st. 2, Tyumen, Russian Federation, 625041
| | - Mikhail Levchenko
- All-Russian Scientific Research Institute of Veterinary Entomology and Arachnology, Branch of Federal State Institution Federal Research Centre Tyumen Scientific Centre, Siberian Branch of the Russian Academy of Sciences (ASRIVEA - Branch of Tyumen Scientific Centre SB RAS), Institutskaya st. 2, Tyumen, Russian Federation, 625041
| | - Bahlol Rahimi
- Department of Health Information Technology, School of Applied Medical Sciences, Urmia University of Medical Sciences, Urmia, Iran
| | - Saber Gholizadeh
- Social Determinants of Health Research Center, Clinical Research Institute, Urmia University of Medical Sciences, Urmia, Iran. .,Medical Entomology Department, School of Public Health, Urmia University of Medical Sciences, Urmia, Iran.
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25
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Finney M, McKenzie BA, Rabaovola B, Sutcliffe A, Dotson E, Zohdy S. Widespread zoophagy and detection of Plasmodium spp. in Anopheles mosquitoes in southeastern Madagascar. Malar J 2021; 20:25. [PMID: 33413398 PMCID: PMC7791646 DOI: 10.1186/s12936-020-03539-4] [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: 08/18/2020] [Accepted: 12/07/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Malaria is a top cause of mortality on the island nation of Madagascar, where many rural communities rely on subsistence agriculture and livestock production. Understanding feeding behaviours of Anopheles in this landscape is crucial for optimizing malaria control and prevention strategies. Previous studies in southeastern Madagascar have shown that Anopheles mosquitoes are more frequently captured within 50 m of livestock. However, it remains unknown whether these mosquitoes preferentially feed on livestock. Here, mosquito blood meal sources and Plasmodium sporozoite rates were determined to evaluate patterns of feeding behaviour in Anopheles spp. and malaria transmission in southeastern Madagascar. METHODS Across a habitat gradient in southeastern Madagascar 7762 female Anopheles spp. mosquitoes were collected. Of the captured mosquitoes, 492 were visibly blood fed and morphologically identifiable, and a direct enzyme-linked immunosorbent assay (ELISA) was used to test for swine, cattle, chicken, human, and dog blood among these specimens. Host species identification was confirmed for multiple blood meals using PCR along with Sanger sequencing. Additionally, 1,607 Anopheles spp. were screened for the presence of Plasmodium falciparum, P. vivax-210, and P. vivax 247 circumsporozoites (cs) by ELISA. RESULTS Cattle and swine accounted, respectively, for 51% and 41% of all blood meals, with the remaining 8% split between domesticated animals and humans. Of the 1,607 Anopheles spp. screened for Plasmodium falciparum, Plasmodium vivax 210, and Plasmodium vivax 247 cs-protein, 45 tested positive, the most prevalent being P. vivax 247, followed by P. vivax 210 and P. falciparum. Both variants of P. vivax were observed in secondary vectors, including Anopheles squamosus/cydippis, Anopheles coustani, and unknown Anopheles spp. Furthermore, evidence of coinfection of P. falciparum and P. vivax 210 in Anopheles gambiae sensu lato (s.l.) was found. CONCLUSIONS Here, feeding behaviour of Anopheles spp. mosquitoes in southeastern Madagascar was evaluated, in a livestock rich landscape. These findings suggest largely zoophagic feeding behaviors of Anopheles spp., including An. gambiae s.l. and presence of both P. vivax and P. falciparum sporozoites in Anopheles spp. A discordance between P. vivax reports in mosquitoes and humans exists, suggesting high prevalence of P. vivax circulating in vectors in the ecosystem despite low reports of clinical vivax malaria in humans in Madagascar. Vector surveillance of P. vivax may be relevant to malaria control and elimination efforts in Madagascar. At present, the high proportion of livestock blood meals in Madagascar may play a role in buffering (zooprophylaxis) or amplifying (zoopotentiation) the impacts of malaria. With malaria vector control efforts focused on indoor feeding behaviours, complementary approaches, such as endectocide-aided vector control in livestock may be an effective strategy for malaria reduction in Madagascar.
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Affiliation(s)
- Micaela Finney
- College of Science and Mathematics, Auburn University, Auburn, AL, USA
| | - Benjamin A McKenzie
- School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, USA
| | | | - Alice Sutcliffe
- Division of Parasitic Diseases and Malaria, Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Ellen Dotson
- Division of Parasitic Diseases and Malaria, Entomology Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
| | - Sarah Zohdy
- School of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, USA. .,College of Veterinary Medicine, Auburn University, Auburn, AL, USA.
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Chaccour C. Veterinary endectocides for malaria control and elimination: prospects and challenges. Philos Trans R Soc Lond B Biol Sci 2020; 376:20190810. [PMID: 33357062 DOI: 10.1098/rstb.2019.0810] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Residual transmission is the persistence of malaria transmission after scale-up of appropriate vector control tools and is one of the key challenges for malaria elimination today. Although long associated with outdoor biting, other mosquito behaviours such as partly feeding upon animals contribute greatly to sustaining transmission. Peri-domestic livestock can be used as decoy to protect humans from blood-seeking vectors but this approach often leads to an increased malaria risk in a phenomenon known as zoopotentiation. Treating the said livestock with drugs capable of killing intestinal parasites as well as mosquitoes that feed upon them has the potential to tackle malaria through a previously unexplored mechanism. The advantages and challenges associated with this approach are briefly discussed here. Numerous references are purposely provided. This article is part of the theme issue 'Novel control strategies for mosquito-borne diseases'.
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Affiliation(s)
- Carlos Chaccour
- ISGlobal, Hospital Clínic - Universitat de Barcelona, Rosello 132, 5ª 2ª, 08036 Barcelona, Spain.,Ifakara Health Institute, Off Mlabani Passage, PO Box 53, Ifakara, United Republic of Tanzania.,Faculty of Medicine, Universidad de Navarra, Calle de Irunlarrea 1, 31008 Pamplona, Spain
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27
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Mlacha YP, Chaki PP, Muhili A, Massue DJ, Tanner M, Majambere S, Killen GF, Govella NJ. Reduced human-biting preferences of the African malaria vectors Anopheles arabiensis and Anopheles gambiae in an urban context: controlled, competitive host-preference experiments in Tanzania. Malar J 2020; 19:418. [PMID: 33218346 PMCID: PMC7678205 DOI: 10.1186/s12936-020-03495-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 11/11/2020] [Indexed: 11/26/2022] Open
Abstract
BACKGROUND Host preference is a critical determinant of human exposure to vector-borne infections and the impact of vector control interventions. Widespread use of long-lasting insecticide-treated nets (LLINs) and indoor residual spraying (IRS) across sub-Saharan Africa, which protect humans against mosquitoes, may select for altered host preference traits of malaria vectors over the long term. Here, the host preferences of Anopheles arabiensis and Anopheles gambiae sensu stricto (s.s.) were experimentally assessed in the field, using direct host-preference assays in two distinct ecological settings in Tanzania. METHODS Eight Ifakara Tent Trap (ITT), four baited with humans and four with bovine calves, were simultaneously used to catch malaria vectors in open field sites in urban and rural Tanzania. The numbers of mosquitoes collected in human-baited traps versus calf-baited traps were used to estimate human feeding preference for each site's vector species. RESULTS The estimated proportion [95% confidence interval (CI)] of mosquitoes attacking humans rather than cattle was 0.60 [0.40, 0.77] for An. arabiensis in the rural setting and 0.61 [0.32, 0.85] for An. gambiae s.s. in the urban setting, indicating no preference for either host in both cases (P = 0.32 and 0.46, respectively) and no difference in preference between the two (Odds Ratio (OR) [95%] = 0.95 [0.30, 3.01], P = 0.924). However, only a quarter of An. arabiensis in the urban setting attacked humans (0.25 [0.09, 0.53]), indicating a preference for cattle that approached significance (P = 0.08). Indeed, urban An. arabiensis were less likely to attack humans rather than cattle when compared to the same species in the rural setting (OR [95%] = 0.21 [0.05, 0.91], P = 0.037). CONCLUSION Urban An. arabiensis had a stronger preference for cattle than the rural population and urban An. gambiae s.s. showed no clear preference for either humans or cattle. In the urban setting, both species exhibited stronger tendencies to attack cattle than previous studies of the same species in rural contexts. Cattle keeping may, therefore, particularly limit the impact of human-targeted vector control interventions in Dar es Salaam and perhaps in other African towns and cities.
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Affiliation(s)
- Yeromin P Mlacha
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania.
- Swiss Tropical and Public Health Institute, Basel, Switzerland.
- University of Basel, Basel, Switzerland.
| | - Prosper P Chaki
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- The Pan-African Mosquito Control Association (PAMCA), KEMRI Headquarters, Mbagathi Road, Nairobi, 54840-00200, Nairobi, Kenya
| | - Athuman Muhili
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
| | - Dennis J Massue
- Univerity of Dar Es Salaam, Mbeya College of Health and Allied Sciences, P.O. Box 608, Mbeya, United Republic of Tanzania
- Amani Research Centre, National Institute for Medical Research, P.O. Box 81, Muheza-Tanga, United Republic of Tanzania
| | - Marcel Tanner
- Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Silas Majambere
- The Pan-African Mosquito Control Association (PAMCA), KEMRI Headquarters, Mbagathi Road, Nairobi, 54840-00200, Nairobi, Kenya
| | - Gerry F Killen
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Vector Biology Department, Pembroke Place, Liverpool, L3 5QA, UK
- School of Biological, Earth & Environmental Sciences and Environmental Research Institute, University College Cork, Cork, Republic of Ireland
| | - Nicodem J Govella
- Ecological Sciences Department, Ifakara Health Institute, Environmental Health, Kiko Avenue, P.O. Box 78373, Mikocheni, Dar es Salaam, United Republic of Tanzania
- The Nelson Mandela, African Institution of Science and Technology, The School of Life Science and Bio-Engineering (LISBE), P.O.BOX 447, Tengeru, Arusha, United Republic of Tanzania
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Boussinesq M, Enyong P, Chounna-Ndongmo P, Njouendou AJ, Pion SD, Rech A, Roberge C, Gaudriault G, Wanji S. Effects of an injectable long-acting formulation of ivermectin on Onchocerca ochengi in zebu cattle. ACTA ACUST UNITED AC 2020; 27:36. [PMID: 32420864 PMCID: PMC7233116 DOI: 10.1051/parasite/2020036] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2019] [Accepted: 05/05/2020] [Indexed: 11/14/2022]
Abstract
The availability of a safe macrofilaricidal drug would help to accelerate onchocerciasis elimination. A trial was conducted in Cameroon to evaluate the effects of a subcutaneous injectable long-acting formulation of ivermectin (LAFI) on the microfilariae (mf) and adult stages of Onchocerca ochengi. Ten zebu cattle naturally infected with the parasite were injected subcutaneously with either 500 mg (group A, N = 4), or 1000 mg long-acting ivermectin (group B, N = 4) or the vehicle (group C, N = 2). Skin samples were collected from each animal before, and 6, 12, and 24 months after treatment to measure microfilarial densities (MFDs). Nodules excised before, and 6 and 12 months after treatment were examined histologically to assess the adult worms’ viability and reproductive status. Blood samples were collected at pre-determined time-points to obtain pharmacokinetic data. Before treatment, the average O. ochengi MFDs were similar in the three groups. Six months after treatment, all animals in groups A and B were free of skin mf, whereas those in group C still showed high MFDs (mean = 324.5 mf/g). Only one ivermectin-treated animal (belonging to group A) had skin mf 12 months after treatment (0.9 mf/g). At 24 months, another animal in group A showed skin mf (10.0 mf/g). The histologic examination of nodules at 6 and 12 months showed that LAFI was not macrofilaricidal but had a strong effect on embryogenesis. The new LAFI regimen might be an additional tool to accelerate the elimination of human onchocerciasis in specific settings.
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Affiliation(s)
- Michel Boussinesq
- Recherches Translationnelles sur le VIH et les Maladies Infectieuses (TransVIHMI), UMI233 IRD-U1175 INSERM-Université de Montpellier, BP 64501, 34394 Montpellier Cedex 5, France
| | - Peter Enyong
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
| | | | - Abdel-Jelil Njouendou
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
| | - Sébastien David Pion
- Recherches Translationnelles sur le VIH et les Maladies Infectieuses (TransVIHMI), UMI233 IRD-U1175 INSERM-Université de Montpellier, BP 64501, 34394 Montpellier Cedex 5, France
| | - Anthony Rech
- MedinCell S.A., 3 Rue des Frères Lumière, 34830 Jacou, France
| | | | | | - Samuel Wanji
- Research Foundation for Tropical Diseases and the Environment, PO Box 474, Buea, Cameroon
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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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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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31
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Meredith HR, Furuya-Kanamori L, Yakob L. Optimising systemic insecticide use to improve malaria control. BMJ Glob Health 2019; 4:e001776. [PMID: 31798988 PMCID: PMC6861066 DOI: 10.1136/bmjgh-2019-001776] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2019] [Revised: 09/26/2019] [Accepted: 10/12/2019] [Indexed: 01/08/2023] Open
Abstract
Background Long-lasting insecticidal nets and indoor residual sprays have significantly reduced the burden of malaria. However, several hurdles remain before elimination can be achieved: mosquito vectors have developed resistance to public health insecticides, including pyrethroids, and have altered their biting behaviour to avoid these indoor control tools. Systemic insecticides, drugs applied directly to blood hosts to kill mosquitoes that take a blood meal, offer a promising vector control option. To date, most studies focus on repurposing ivermectin, a drug used extensively to treat river blindness. There is concern that overdependence on a single drug will inevitably repeat past experiences with the rapid spread of pyrethroid resistance in malaria vectors. Diversifying the arsenal of systemic insecticides used for mass drug administration would improve this strategy’s sustainability. Methods Here, a review was conducted to identify systemic insecticide candidates and consolidate their pharmacokinetic/pharmacodynamic properties. The impact of alternative integrated vector control options and different dosing regimens on malaria transmission reduction are illustrated through mathematical model simulation. Results The review identified drugs from four classes commonly used in livestock and companion animals: avermectins, milbemycins, isoxazolines and spinosyns. Simulations predicted that isoxazolines and spinosyns are promising candidates for mass drug administration, as they were predicted to need less frequent application than avermectins and milbemycins to maintain mosquitocidal blood concentrations. Conclusions These findings will provide a guide for investigating and applying different systemic insecticides to achieve more effective and sustainable control of malaria transmission.
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Affiliation(s)
- Hannah R Meredith
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK.,Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Luis Furuya-Kanamori
- Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australian Capital Territory, Australia
| | - Laith Yakob
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, UK
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Dreyer SM, Leiva D, Magaña M, Pott M, Kay J, Cruz A, Achee NL, Grieco JP, Vaughan JA. Fipronil and ivermectin treatment of cattle reduced the survival and ovarian development of field-collected Anopheles albimanus in a pilot trial conducted in northern Belize. Malar J 2019; 18:296. [PMID: 31464619 PMCID: PMC6716933 DOI: 10.1186/s12936-019-2932-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 08/23/2019] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Most malaria vector control programmes rely on indoor residual spraying of insecticides and insecticide-treated bed nets. This is effective against vector species that feed indoors at night and rest inside the house afterwards. In Central America, malaria vectors have different behaviours and are typically exophagic (i.e., bite outdoors), exophilic (i.e., remain outdoors after feeding), and zoophagic (i.e., as likely to feed on non-humans as humans). Thus, malaria elimination in Central America may require additional tactics. This pilot study investigated whether commercially-available products used to treat livestock for ticks could also be used to kill and/or sterilize zoophagic malaria vectors that feed on treated cattle in Belize. METHODS Cattle were treated with either a pour-on formulation of 1% fipronil (3 heifers) or injection of 1% ivemectin (1 heifer). Control heifers (n = 2) were left untreated. Field-collected Anopheles albimanus contained in screen-top cages were strapped onto cattle at 2, 5, 7, and 14 days after treatment. Mosquito mortality was monitored once a day for 4 successive days. Surviving mosquitoes were dissected to assess blood meal digestion and ovarian development. RESULTS A total of 1078 female An. albimanus mosquitoes were fed and monitored for mortality. Both fipronil and ivermectin significantly reduced survivorship of An. albimanus for up to 7 days after treatment. By 14 days, efficacy had declined. The ivermectin treatment completely lost its effectiveness and even though the fipronil-treated heifers were still killing significantly more mosquitoes than the untreated heifers, the amount of mosquito killing had diminished greatly. Both treatments significantly reduced ovary development in mosquitoes fed on treated cattle for the duration of the 2-week trial. CONCLUSIONS Treatment of cattle in northern Belize with topical fipronil and injectable ivermectin had significant lethal and sublethal effects on wild An. albimanus females. These results suggest that efforts towards eliminating residual transmission of malaria by zoophagic vectors in Central America may benefit by the judicious, targeted treatment of livestock with mosquitocidal compounds, such as fipronil or ivermectin.
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Affiliation(s)
- Staci M Dreyer
- Biology Department, University of North Dakota, Grand Forks, ND, 58202, USA
| | - Donovan Leiva
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Marla Magaña
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Marie Pott
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Jonathan Kay
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | - Alvaro Cruz
- Belize Vector and Ecology Center, Orange Walk Town, Belize
| | | | - John P Grieco
- University of Notre Dame, South Bend, IN, 46556, USA
| | - Jefferson A Vaughan
- Biology Department, University of North Dakota, Grand Forks, ND, 58202, USA.
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Sharun K, Shyamkumar TS, Aneesha VA, Dhama K, Pawde AM, Pal A. Current therapeutic applications and pharmacokinetic modulations of ivermectin. Vet World 2019; 12:1204-1211. [PMID: 31641298 PMCID: PMC6755388 DOI: 10.14202/vetworld.2019.1204-1211] [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: 05/17/2019] [Accepted: 06/29/2019] [Indexed: 12/22/2022] Open
Abstract
Ivermectin is considered to be a wonder drug due to its broad-spectrum antiparasitic activity against both ectoparasites and endoparasites (under class of endectocide) and has multiple applications in both veterinary and human medicine. In particular, ivermectin is commonly used in the treatment of different kinds of infections and infestations. By altering the vehicles used in the formulations, the pharmacokinetic properties of different ivermectin preparations can be altered. Since its development, various vehicles have been evaluated to assess the efficacy, safety, and therapeutic systemic concentrations of ivermectin in different species. A subcutaneous route of administration is preferred over a topical or an oral route for ivermectin due to superior bioavailability. Different formulations of ivermectin have been developed over the years, such as stabilized aqueous formulations, osmotic pumps, controlled release capsules, silicone carriers, zein microspheres, biodegradable microparticulate drug delivery systems, lipid nanocapsules, solid lipid nanoparticles, sustained-release ivermectin varnish, sustained-release ivermectin-loaded solid dispersion suspension, and biodegradable subcutaneous implants. However, several reports of ivermectin resistance have been identified in different parts of the world over the past few years. Continuous use of suboptimal formulations or sub-therapeutic plasma concentrations may predispose an individual to resistance toward ivermectin. The current research trend is focused toward the need for developing ivermectin formulations that are stable, effective, and safe and that reduce the number of doses required for complete clinical cure in different parasitic diseases. Therefore, single-dose long-acting preparations of ivermectin that provide effective therapeutic drug concentrations need to be developed and commercialized, which may revolutionize drug therapy and prophylaxis against various parasitic diseases in the near future. The present review highlights the current advances in pharmacokinetic modulation of ivermectin formulations and their potent therapeutic applications, issues related to emergence of ivermectin resistance, and future trends of ivermectin usage.
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Affiliation(s)
- Khan Sharun
- Division of Surgery, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - T. S. Shyamkumar
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - V. A. Aneesha
- Division of Pharmacology and Toxicology, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - Kuldeep Dhama
- Division of Pathology, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - Abhijit Motiram Pawde
- Division of Surgery, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
| | - Amar Pal
- Division of Surgery, ICAR-Indian Veterinary Research Institute, Bareilly, Uttar Pradesh, India
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Patterns of anopheline feeding/resting behaviour and Plasmodium infections in North Cameroon, 2011-2014: implications for malaria control. Parasit Vectors 2019; 12:297. [PMID: 31196161 PMCID: PMC6567421 DOI: 10.1186/s13071-019-3552-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 06/03/2019] [Indexed: 11/10/2022] Open
Abstract
Background Effective malaria control relies on evidence-based interventions. Anopheline behaviour and Plasmodium infections were investigated in North Cameroon, following long-lasting insecticidal net (LLIN) distribution in 2010. Methods During four consecutive years from 2011 to 2014, adult mosquitoes were collected indoors, outdoors and in exit traps across 38 locations in the Garoua, Pitoa and Mayo-Oulo health districts. Anophelines were morphologically and molecularly identified, then analysed for blood meal origins and Plasmodium falciparum circumsporozoite protein (Pf-CSP). Blood from children under 5 years-old using LLINs was examined for Plasmodium infections. Results Overall, 9376 anophelines belonging to 14 species/sibling species were recorded. Anopheles gambiae (s.l.) [An. arabiensis (73.3%), An. coluzzii (17.6%) and An. gambiae (s.s.) (9.1%)] was predominant (72%), followed by An. funestus (s.l.) (20.5%) and An. rufipes (6.5%). The recorded blood meals were mainly from humans (28%), cattle (15.6%) and sheep (11.6%) or mixed (45%). Pf-CSP rates were higher indoors (3.2–5.4%) versus outdoors (0.8–2.0%), and increased yearly (χ2 < 18, df = 10, P < 0.03). Malaria prevalence in children under 5 years-old, in households using LLINs was 30% (924/3088). Conclusions The present study revealed the variability of malaria vector resting and feeding behaviour, and the persistence of Plasmodium infections regardless the use of LLINs. Supplementary interventions to LLINs are therefore needed to sustain malaria prevention in North Cameroon.
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Imbahale SS, Montaña Lopez J, Brew J, Paaijmans K, Rist C, Chaccour C. Mapping the potential use of endectocide-treated cattle to reduce malaria transmission. Sci Rep 2019; 9:5826. [PMID: 30967606 PMCID: PMC6456610 DOI: 10.1038/s41598-019-42356-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 03/29/2019] [Indexed: 12/27/2022] Open
Abstract
Treating cattle with endectocide is a longstanding veterinary practice to reduce the load of endo and ectoparasites, but has the potential to be added to the malaria control and elimination toolbox, as it also kills malaria mosquitoes feeding on the animals. Here we used openly available data to map the areas of the African continent where high malaria prevalence in 2-10 year old children coincides with a high density of cattle and high density of the partly zoophilic malaria vector Anopheles arabiensis. That is, mapping the areas where treating cattle with endectocide would potentially have the greatest impact on reducing malaria transmission. In regions of Africa that are not dominated by rainforest nor desert, the map shows a scatter of areas in several countries where this intervention shows potential, including central and eastern sub-Saharan Africa. The savanna region underneath the Sahel in West Africa appears as the climatic block that would benefit to the largest extent from this intervention, encompassing several countries. West Africa currently presents the highest under-10 malaria prevalence and elimination within the next twenty years cannot be contemplated there with currently available interventions alone, making the use of endectocide treated cattle as a complementary intervention highly appealing.
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Affiliation(s)
- Susan S Imbahale
- Department of Applied and Technical Biology, The Technical University of Kenya, Nairobi, Kenya
| | - Julia Montaña Lopez
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique
| | - Joe Brew
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain
| | - Krijn Paaijmans
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique.,Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.,The Biodesign Center for Immunotherapy, Vaccines and Virotherapy, Arizona State University, Tempe, AZ, USA
| | - Cassidy Rist
- Virginia-Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, VA, USA
| | - Carlos Chaccour
- ISGlobal, Hospital Clínic-Universitat de Barcelona, Barcelona, Spain. .,Centro de Investigação em Saúde de Manhiça, Maputo, Mozambique. .,Ifakara Health Institute, Ifakara, United Republic of Tanzania. .,Facultad de Medicina, Universidad de Navarra, Pamplona, Spain.
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Hewitt SE. Let's 'cut to the chase' on malaria elimination in the Greater Mekong Subregion. Trans R Soc Trop Med Hyg 2019; 113:161-162. [PMID: 30551174 DOI: 10.1093/trstmh/try125] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Revised: 11/01/2018] [Accepted: 11/15/2018] [Indexed: 11/14/2022] Open
Abstract
The Greater Mekong Subregion has made remarkable progress towards eliminating malaria in recent years, but efforts are now faltering in some areas. The development of tools to control forest-based transmission is taking too long and efforts to control malaria among high-risk mobile people are failing. If countries are to meet their elimination targets and prevent the spread of multidrug-resistant falciparum malaria, urgent and radical changes will be required. This commentary proposes changes in the approach to the development and roll-out of new tools as well as changes to the management of elimination efforts targeting transmission in forests and forest-farms.
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Affiliation(s)
- Sean E Hewitt
- VBDC Consulting Ltd., Fronteifi House, Cardigan, United Kingdom
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Orsborne J, Furuya-Kanamori L, Jeffries CL, Kristan M, Mohammed AR, Afrane YA, O'Reilly K, Massad E, Drakeley C, Walker T, Yakob L. Investigating the blood-host plasticity and dispersal of Anopheles coluzzii using a novel field-based methodology. Parasit Vectors 2019; 12:143. [PMID: 30909960 PMCID: PMC6434891 DOI: 10.1186/s13071-019-3401-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 03/15/2019] [Indexed: 11/10/2022] Open
Abstract
Background The biting behaviour and dispersal of insect vectors in the field underlies the transmission of many diseases. Here, a novel collection methodology coupled with the molecular analysis of blood-meal sources and digestion rates is introduced with the aim of aiding the understanding of two critical and relatively understudied mosquito behaviours: plasticity in blood-host choice and vector dispersal. Results A collection strategy utilising a transect of mosquito traps placed at 50 m intervals allowed the collection of blood-fed Anopheles coluzzii from a malaria-endemic village of southern Ghana where human host availability ranged from zero (a cattle pen), increasing until humans were the dominant host choice (the middle of the village). Blood-meal analysis using PCR showed statistically significant variation in blood-meal origins for mosquitoes collected across the 250 m transect: with decreasing trend in Bovine Blood Index (OR = 0.60 95% CI: 0.49–0.73, P < 0.01) and correspondingly, an increasing trend in Human Blood Index (OR = 1.50 95% CI: 1.05–2.16, P = 0.028) as the transect approached the village. Using qPCR, the host DNA remaining in the blood meal was quantified for field-caught mosquitoes and calibrated according to timed blood digestion in colony mosquitoes. Time since blood meal was consumed and the corresponding distance the vector was caught from its blood-host allowed the estimation of An. coluzzii dispersal rates. Within 7 hours of feeding, mosquitoes typically remained within 50 m of their blood-host but at 60 hours they had dispersed up to 250 m. Conclusions Using this methodology the remarkably small spatial scale at which An. coluzzii blood-host choice can change was demonstrated. In addition, conducting qPCR on host blood from field-caught mosquitoes and calibrating with timed experiments with colonised mosquitoes presents a novel methodology for investigating the dispersal behaviour of vectors. Future adaptations to this novel method to make it broadly applicable to other types of setting are also discussed.
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Affiliation(s)
- James Orsborne
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Luis Furuya-Kanamori
- Department of Population Medicine, College of Medicine, Qatar University, Doha, Qatar.,Research School of Population Health, College of Health and Medicine, Australian National University, Canberra, Australia
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Abdul Rahim Mohammed
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Kathleen O'Reilly
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Eduardo Massad
- School of Applied Mathematics, Fundacao Getulio Vargas, Rio de Janeiro, Brazil
| | - Chris Drakeley
- Department of Immunology & Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Laith Yakob
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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Mashatola T, Ndo C, Koekemoer LL, Dandalo LC, Wood OR, Malakoane L, Poumachu Y, Lobb LN, Kaiser M, Bourtzis K, Munhenga G. A review on the progress of sex-separation techniques for sterile insect technique applications against Anopheles arabiensis. Parasit Vectors 2018; 11:646. [PMID: 30583746 PMCID: PMC6304763 DOI: 10.1186/s13071-018-3219-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The feasibility of the sterile insect technique (SIT) as a malaria vector control strategy against Anopheles arabiensis has been under investigation over the past decade. One of the critical steps required for the application of this technique to mosquito control is the availability of an efficient and effective sex-separation system. Sex-separation systems eliminate female mosquitoes from the production line prior to irradiation and field release of sterile males. This is necessary because female mosquitoes can transmit pathogens such as malaria and, therefore, their release must be prevented. Sex separation also increases the efficiency of an SIT programme. Various sex-separation strategies have been explored including the exploitation of developmental and behavioural differences between male and female mosquitoes, and genetic approaches. Most of these are however species-specific and are not indicated for the major African malaria vectors such as An. arabiensis. As there is currently no reliable sex-separation method for An. arabiensis, various strategies were explored in an attempt to develop a robust system that can be applied on a mass-rearing scale. The progress and challenges faced during the development of a sexing system for future pilot and/or large-scale SIT release programmes against An. arabiensis are reviewed here. Three methods of sex separation were examined. The first is the use of pupal size for gender prediction. The second is the elimination of blood-feeding adult females through the addition of an endectocide to a blood meal source. The third is the establishment of a genetic sexing strain (GSS) carrying an insecticide resistance selectable marker (dieldrin-resistance rdl gene and/or other GABA receptor antagonists that can be used as alternative insecticides to dieldrin) or a temperature-sensitive lethal marker.
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Affiliation(s)
- Thabo Mashatola
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Cyrille Ndo
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Centre for Research in Infectious Disease (CRI), Yaoundé, Cameroon
| | - Lizette L. Koekemoer
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Leonard C. Dandalo
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Oliver R. Wood
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lerato Malakoane
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Yacouba Poumachu
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Vector Borne Disease Laboratory of the Applied Biology and Ecology Research Unit (VBDL-URBEA) Department of Animal Biology, Faculty of Sciences of the University of Dschang, Dschang, Cameroon
| | - Leanne N. Lobb
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Maria Kaiser
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Kostas Bourtzis
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Givemore Munhenga
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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Orsborne J, Furuya-Kanamori L, Jeffries CL, Kristan M, Mohammed AR, Afrane YA, O'Reilly K, Massad E, Drakeley C, Walker T, Yakob L. Using the human blood index to investigate host biting plasticity: a systematic review and meta-regression of the three major African malaria vectors. Malar J 2018; 17:479. [PMID: 30563533 PMCID: PMC6299493 DOI: 10.1186/s12936-018-2632-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Accepted: 12/14/2018] [Indexed: 12/17/2022] Open
Abstract
Background The proportion of mosquito blood-meals that are of human origin, referred to as the ‘human blood index’ or HBI, is a key determinant of malaria transmission. Methods A systematic review was conducted followed by meta-regression of the HBI for the major African malaria vectors. Results Evidence is presented for higher HBI among Anopheles gambiae (M/S forms and Anopheles coluzzii/An. gambiae sensu stricto are not distinguished for most studies and, therefore, combined) as well as Anopheles funestus when compared with Anopheles arabiensis (prevalence odds ratio adjusted for collection location [i.e. indoor or outdoor]: 1.62; 95% CI 1.09–2.42; 1.84; 95% CI 1.35–2.52, respectively). This finding is in keeping with the entomological literature which describes An. arabiensis to be more zoophagic than the other major African vectors. However, analysis also revealed that HBI was more associated with location of mosquito captures (R2 = 0.29) than with mosquito (sibling) species (R2 = 0.11). Conclusions These findings call into question the appropriateness of current methods of assessing host preferences among disease vectors and have important implications for strategizing vector control. Electronic supplementary material The online version of this article (10.1186/s12936-018-2632-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- James Orsborne
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Luis Furuya-Kanamori
- Department of Population Medicine, College of Medicine, Qatar University, Doha, Qatar
| | - Claire L Jeffries
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Mojca Kristan
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Abdul Rahim Mohammed
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Yaw A Afrane
- Department of Medical Microbiology, College of Health Sciences, University of Ghana, Korle Bu, Accra, Ghana
| | - Kathleen O'Reilly
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Eduardo Massad
- School of Applied Mathematics, Fundacao Getulio Vargas, Rio de Janeiro, Brazil
| | - Chris Drakeley
- Department of Immunology & Infection, London School of Hygiene & Tropical Medicine, London, UK
| | - Thomas Walker
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK
| | - Laith Yakob
- Department of Disease Control, London School of Hygiene & Tropical Medicine, London, UK.
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40
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Burrows J, Slater H, Macintyre F, Rees S, Thomas A, Okumu F, Hooft van Huijsduijnen R, Duparc S, Wells TNC. A discovery and development roadmap for new endectocidal transmission-blocking agents in malaria. Malar J 2018; 17:462. [PMID: 30526594 PMCID: PMC6287360 DOI: 10.1186/s12936-018-2598-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/24/2018] [Indexed: 11/10/2022] Open
Abstract
Reaching the overall goal of eliminating malaria requires halting disease transmission. One approach to blocking transmission is to prevent passage of the parasite to a mosquito, by preventing formation or transmission of gametocytes. An alternative approach, pioneered in the veterinary field, is to use endectocides, which are molecules that render vertebrate blood meals toxic for the mosquito vector, also killing the parasite. Field studies and modelling suggest that reducing the lifespan of the mosquito may significantly reduce transmission, given the lengthy maturation process of the parasite. To guide the development of new endectocides, or the reformulation of existing molecules, it is important to construct a framework of the required attributes, commonly called the target candidate profile. Here, using a combination of insights from current endectocides, mathematical models of the malaria transmission dynamics, and known impacts of vector control, a target candidate profile (TCP-6) and a regulatory strategy are proposed for a transmission reducing agent. The parameters chosen can be used to assess the potential of a new medicine, independent of whether it has classical endectocide activity, reduces the insect and parasite lifespan or any combination of all three, thereby constituting an ‘endectocidal transmission blocking’ paradigm.
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Affiliation(s)
- Jeremy Burrows
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland.
| | - Hannah Slater
- PATH, 2201 Westlake Avenue, Seattle, WA, 98121, USA.,Department of Infectious Disease Epidemiology, MRC Centre for Global Disease Analysis, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - Fiona Macintyre
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Sarah Rees
- Innovative Vector Control Consortium, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Anna Thomas
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Fredros Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Off Mlabani Passage, Ifakara, Morogoro, United Republic of Tanzania.,School of Public Health, Faculty of Health Sciences, University of the Witwatersrand, Parktown, Republic of South Africa.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, UK
| | | | - Stephan Duparc
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
| | - Timothy N C Wells
- Medicines for Malaria Venture, Route de Pré Bois 20, 1215, Geneva 15, Switzerland
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41
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Ng'habi K, Viana M, Matthiopoulos J, Lyimo I, Killeen G, Ferguson HM. Mesocosm experiments reveal the impact of mosquito control measures on malaria vector life history and population dynamics. Sci Rep 2018; 8:13949. [PMID: 30224714 PMCID: PMC6141522 DOI: 10.1038/s41598-018-31805-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 08/24/2018] [Indexed: 11/29/2022] Open
Abstract
The impact of control measures on mosquito vector fitness and demography is usually estimated from bioassays or indirect variables in the field. Whilst indicative, neither approach is sufficient to quantify the potentially complex response of mosquito populations to combined interventions. Here, large replicated mesocosms were used to measure the population-level response of the malaria vector Anopheles arabiensis to long-lasting insecticidal nets (LLINs) when used in isolation, or combined with insecticidal eave louvers (EL), or treatment of cattle with the endectocide Ivermectin (IM). State-space models (SSM) were fit to these experimental data, revealing that LLIN introduction reduced adult mosquito survival by 91% but allowed population persistence. ELs provided no additional benefit, but IM reduced mosquito fecundity by 59% and nearly eliminated all populations when combined with LLINs. This highlights the value of IM for integrated vector control, and mesocosm population experiments combined with SSM for identifying optimal combinations for vector population elimination.
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Affiliation(s)
- Kija Ng'habi
- Ifakara Health Institute, Environmental Health and Ecological Sciences, Ifakara, United Republic of Tanzania
- School of Health Sciences, University of Dar es Salaam, Dar es Salaam, Tanzania
| | - Mafalda Viana
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - Jason Matthiopoulos
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - Issa Lyimo
- Ifakara Health Institute, Environmental Health and Ecological Sciences, Ifakara, United Republic of Tanzania
| | - Gerry Killeen
- Ifakara Health Institute, Environmental Health and Ecological Sciences, Ifakara, United Republic of Tanzania
- Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, United Kingdom
| | - Heather M Ferguson
- Institute of Biodiversity, Animal Health and Comparative Medicine, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
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