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Hancock PA, Ochomo E, Messenger LA. Genetic surveillance of insecticide resistance in African Anopheles populations to inform malaria vector control. Trends Parasitol 2024; 40:604-618. [PMID: 38760258 DOI: 10.1016/j.pt.2024.04.016] [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: 02/28/2024] [Revised: 04/24/2024] [Accepted: 04/26/2024] [Indexed: 05/19/2024]
Abstract
Insecticide resistance in malaria vector populations poses a major threat to malaria control, which relies largely on insecticidal interventions. Contemporary vector-control strategies focus on combatting resistance using multiple insecticides with differing modes of action within the mosquito. However, diverse genetic resistance mechanisms are present in vector populations, and continue to evolve. Knowledge of the spatial distribution of these genetic mechanisms, and how they impact the efficacy of different insecticidal products, is critical to inform intervention deployment decisions. We developed a catalogue of genetic-resistance mechanisms in African malaria vectors that could guide molecular surveillance. We highlight situations where intervention deployment has led to resistance evolution and spread, and identify challenges in understanding and mitigating the epidemiological impacts of resistance.
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Affiliation(s)
- Penelope A Hancock
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.
| | - Eric Ochomo
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya; Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, UK
| | - Louisa A Messenger
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, USA; Parasitology and Vector Biology (PARAVEC) Laboratory, School of Public Health, University of Nevada, Las Vegas, USA
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Lynd A, Gonahasa S, Staedke SG, Oruni A, Maiteki-Sebuguzi C, Hancock PA, Knight E, Dorsey G, Opigo J, Yeka A, Katureebe A, Kyohere M, Hemingway J, Kamya MR, McDermott D, Lucas ER, Donnelly MJ. LLIN Evaluation in Uganda Project (LLINEUP)-effects of a vector control trial on Plasmodium infection prevalence and genotypic markers of insecticide resistance in Anopheles vectors from 48 districts of Uganda. Sci Rep 2024; 14:14488. [PMID: 38914669 PMCID: PMC11196729 DOI: 10.1038/s41598-024-65050-z] [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: 12/07/2023] [Accepted: 06/17/2024] [Indexed: 06/26/2024] Open
Abstract
Pyrethroid bednets treated with the synergist piperonyl butoxide (PBO) offer the possibility of improved vector control in mosquito populations with metabolic resistance. In 2017-2019, we conducted a large-scale, cluster-randomised trial (LLINEUP) to evaluate long-lasting insecticidal nets (LLINs) treated with a pyrethroid insecticide plus PBO (PBO LLINs), as compared to conventional, pyrethroid-only LLINs across 104 health sub-districts (HSDs) in Uganda. In LLINEUP, and similar trials in Tanzania, PBO LLINs were found to provide greater protection against malaria than conventional LLINs, reducing parasitaemia and vector density. In the LLINEUP trial, we conducted cross-sectional household entomological surveys at baseline and then every 6 months for two years, which we use here to investigate longitudinal changes in mosquito infection rate and genetic markers of resistance. Overall, 5395 female Anopheles mosquitoes were collected from 5046 households. The proportion of mosquitoes infected (PCR-positive) with Plasmodium falciparum did not change significantly over time, while infection with non-falciparum malaria decreased in An. gambiae s.s., but not An. funestus. The frequency of genetic markers associated with pyrethroid resistance increased significantly over time, but the rate of change was not different between the two LLIN types. The knock-down resistance (kdr) mutation Vgsc-995S declined over time as Vgsc-995F, the alternative resistance mutation at this codon, increased. Vgsc-995F appears to be spreading into Uganda. Distribution of LLINs in Uganda was previously found to be associated with reductions in parasite prevalence and vector density, but here we show that the proportion of infective mosquitoes remained stable across both PBO and non-PBO LLINs, suggesting that the potential for transmission persisted. The increased frequency of markers of pyrethroid resistance indicates that LLIN distribution favoured the evolution of resistance within local vectors and highlights the potential benefits of resistance management strategies.Trial registration: This study is registered with ISRCTN, ISRCTN17516395. Registered 14 February 2017, http://www.isrctn.com/ISRCTN17516395 .
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Affiliation(s)
- Amy Lynd
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Samuel Gonahasa
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Sarah G Staedke
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Ambrose Oruni
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | | | | | - Erin Knight
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Grant Dorsey
- University of California, San Francisco, San Francisco, CA, 94110, USA
| | | | - Adoke Yeka
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Agaba Katureebe
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Mary Kyohere
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Janet Hemingway
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
- Department of Medicine, Makerere University, Kampala, Uganda
| | - Daniel McDermott
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Eric R Lucas
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Martin J Donnelly
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
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Okiring J, Gonahasa S, Maiteki-Sebuguzi C, Katureebe A, Bagala I, Mutungi P, Kigozi SP, Namuganga JF, Nankabirwa JI, Kamya MR, Donnelly MJ, Churcher TS, Staedke SG, Sherrard-Smith E. LLIN Evaluation in Uganda Project (LLINEUP): modelling the impact of COVID-19-related disruptions on delivery of long-lasting insecticidal nets on malaria indicators in Uganda. Malar J 2024; 23:180. [PMID: 38844987 PMCID: PMC11157881 DOI: 10.1186/s12936-024-05008-8] [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: 03/05/2024] [Accepted: 06/04/2024] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND Disruptions in malaria control due to COVID-19 mitigation measures were predicted to increase malaria morbidity and mortality in Africa substantially. In Uganda, long-lasting insecticidal nets (LLINs) are distributed nationwide every 3-4 years, but the 2020-2021 campaign was altered because of COVID-19 restrictions so that the timing of delivery of new nets was different from the original plans made by the National Malaria Control Programme. METHODS A transmission dynamics modelling exercise was conducted to explore how the altered delivery of LLINs in 2020-2021 impacted malaria burden in Uganda. Data were available on the planned LLIN distribution schedule for 2020-2021, and the actual delivery. The transmission model was used to simulate 100 health sub-districts, and parameterized to match understanding of local mosquito bionomics, net use estimates, and seasonal patterns based on data collected in 2017-2019 during a cluster-randomized trial (LLINEUP). Two scenarios were compared; simulated LLIN distributions matching the actual delivery schedule, and a comparable scenario simulating LLIN distributions as originally planned. Model parameters were otherwise matched between simulations. RESULTS Approximately 70% of the study population received LLINs later than scheduled in 2020-2021, although some areas received LLINs earlier than planned. The model indicates that malaria incidence in 2020 was substantially higher in areas that received LLINs late. In some areas, early distribution of LLINs appeared less effective than the original distribution schedule, possibly due to attrition of LLINs prior to transmission peaks, and waning LLIN efficacy after distribution. On average, the model simulations predicted broadly similar overall mean malaria incidence in 2021 and 2022. After accounting for differences in cluster population size and LLIN distribution dates, no substantial increase in malaria burden was detected. CONCLUSIONS The model results suggest that the disruptions in the 2020-2021 LLIN distribution campaign in Uganda did not substantially increase malaria burden in the study areas.
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Affiliation(s)
- Jaffer Okiring
- Clinical Epidemiology Unit, Makerere University College of Health Sciences, PO Box 7475, Kampala, Uganda.
- Infectious Diseases Research Collaboration, Kampala, Uganda.
| | | | | | | | - Irene Bagala
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Peter Mutungi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Simon P Kigozi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Joaniter I Nankabirwa
- Clinical Epidemiology Unit, Makerere University College of Health Sciences, PO Box 7475, Kampala, Uganda
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University, Kampala, Uganda
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Wellcome Sanger Institute, Hinxton, UK
| | - Thomas S Churcher
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
| | - Sarah G Staedke
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, UK
- Department of Clinical Research, London School of Hygiene & Tropical Medicine, London, UK
| | - Ellie Sherrard-Smith
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, UK
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Connolly JB, Burt A, Christophides G, Diabate A, Habtewold T, Hancock PA, James AA, Kayondo JK, Lwetoijera DW, Manjurano A, McKemey AR, Santos MR, Windbichler N, Randazzo F. Considerations for first field trials of low-threshold gene drive for malaria vector control. Malar J 2024; 23:156. [PMID: 38773487 PMCID: PMC11110314 DOI: 10.1186/s12936-024-04952-9] [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: 11/29/2023] [Accepted: 04/15/2024] [Indexed: 05/23/2024] Open
Abstract
Sustainable reductions in African malaria transmission require innovative tools for mosquito control. One proposal involves the use of low-threshold gene drive in Anopheles vector species, where a 'causal pathway' would be initiated by (i) the release of a gene drive system in target mosquito vector species, leading to (ii) its transmission to subsequent generations, (iii) its increase in frequency and spread in target mosquito populations, (iv) its simultaneous propagation of a linked genetic trait aimed at reducing vectorial capacity for Plasmodium, and (v) reduced vectorial capacity for parasites in target mosquito populations as the gene drive system reaches fixation in target mosquito populations, causing (vi) decreased malaria incidence and prevalence. Here the scope, objectives, trial design elements, and approaches to monitoring for initial field releases of such gene dive systems are considered, informed by the successful implementation of field trials of biological control agents, as well as other vector control tools, including insecticides, Wolbachia, larvicides, and attractive-toxic sugar bait systems. Specific research questions to be addressed in initial gene drive field trials are identified, and adaptive trial design is explored as a potentially constructive and flexible approach to facilitate testing of the causal pathway. A fundamental question for decision-makers for the first field trials will be whether there should be a selective focus on earlier points of the pathway, such as genetic efficacy via measurement of the increase in frequency and spread of the gene drive system in target populations, or on wider interrogation of the entire pathway including entomological and epidemiological efficacy. How and when epidemiological efficacy will eventually be assessed will be an essential consideration before decisions on any field trial protocols are finalized and implemented, regardless of whether initial field trials focus exclusively on the measurement of genetic efficacy, or on broader aspects of the causal pathway. Statistical and modelling tools are currently under active development and will inform such decisions on initial trial design, locations, and endpoints. Collectively, the considerations here advance the realization of developer ambitions for the first field trials of low-threshold gene drive for malaria vector control within the next 5 years.
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Affiliation(s)
- John B Connolly
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK.
| | - Austin Burt
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK
| | - George Christophides
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
| | - Abdoulaye Diabate
- Institut de Recherche en Sciences de la Santé/Centre Muraz, Bobo-Dioulasso, Burkina Faso
| | - Tibebu Habtewold
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
- Environmental Health and Ecological Science Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Penelope A Hancock
- MRC Centre for Global Infectious Disease Analysis, St. Mary's Campus, Imperial College London, London, UK
| | - Anthony A James
- Departments of Microbiology & Molecular Genetics and Molecular Biology & Biochemistry, University of California, Irvine, USA
| | - Jonathan K Kayondo
- Entomology Department, Uganda Virus Research Institute (UVRI), Entebbe, Uganda
| | | | - Alphaxard Manjurano
- Malaria Research Unit and Laboratory Sciences, Mwanza Medical Research Centre, National Institute for Medical Research, Mwanza, Tanzania
| | - Andrew R McKemey
- Department of Life Sciences, Silwood Park, Imperial College London, London, UK
| | - Michael R Santos
- Foundation for the National Institutes of Health, North Bethesda, MD, USA
| | - Nikolai Windbichler
- Department of Life Sciences, South Kensington Campus, Imperial College London, London, UK
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Odero JO, Nambunga IH, Masalu JP, Mkandawile G, Bwanary H, Hape EE, Njalambaha RM, Tungu P, Ngowo HS, Kaindoa EW, Mapua SA, Kahamba NF, Nelli L, Wondji C, Koekemoer LL, Weetman D, Ferguson HM, Baldini F, Okumu FO. Genetic markers associated with the widespread insecticide resistance in malaria vector Anopheles funestus populations across Tanzania. Parasit Vectors 2024; 17:230. [PMID: 38760849 PMCID: PMC11100202 DOI: 10.1186/s13071-024-06315-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Accepted: 05/03/2024] [Indexed: 05/19/2024] Open
Abstract
BACKGROUND Anopheles funestus is a leading vector of malaria in most parts of East and Southern Africa, yet its ecology and responses to vector control remain poorly understood compared with other vectors such as Anopheles gambiae and Anopheles arabiensis. This study presents the first large-scale survey of the genetic and phenotypic expression of insecticide resistance in An. funestus populations in Tanzania. METHODS We performed insecticide susceptibility bioassays on An. funestus mosquitoes in nine regions with moderate-to-high malaria prevalence in Tanzania, followed by genotyping for resistance-associated mutations (CYP6P9a, CYP6P9b, L119F-GSTe2) and structural variants (SV4.3 kb, SV6.5 kb). Generalized linear models were used to assess relationships between genetic markers and phenotypic resistance. An interactive R Shiny tool was created to visualize the data and support evidence-based interventions. RESULTS Pyrethroid resistance was universal but reversible by piperonyl-butoxide (PBO). However, carbamate resistance was observed in only five of the nine districts, and dichloro-diphenyl-trichloroethane (DDT) resistance was found only in the Kilombero valley, south-eastern Tanzania. Conversely, there was universal susceptibility to the organophosphate pirimiphos-methyl in all sites. Genetic markers of resistance had distinct geographical patterns, with CYP6P9a-R and CYP6P9b-R alleles, and the SV6.5 kb structural variant absent or undetectable in the north-west but prevalent in all other sites, while SV4.3 kb was prevalent in the north-western and western regions but absent elsewhere. Emergent L119F-GSTe2, associated with deltamethrin resistance, was detected in heterozygous form in districts bordering Mozambique, Malawi and the Democratic Republic of Congo. The resistance landscape was most complex in western Tanzania, in Tanganyika district, where all five genetic markers were detected. There was a notable south-to-north spread of resistance genes, especially CYP6P9a-R, though this appears to be interrupted, possibly by the Rift Valley. CONCLUSIONS This study underscores the need to expand resistance monitoring to include An. funestus alongside other vector species, and to screen for both the genetic and phenotypic signatures of resistance. The findings can be visualized online via an interactive user interface and could inform data-driven decision-making for resistance management and vector control. Since this was the first large-scale survey of resistance in Tanzania's An. funestus, we recommend regular updates with greater geographical and temporal coverage.
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Affiliation(s)
- Joel O Odero
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania.
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Ismail H Nambunga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - John P Masalu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Gustav Mkandawile
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Hamis Bwanary
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Emmanuel E Hape
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, South Africa
| | - Rukiyah M Njalambaha
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Patrick Tungu
- Amani Medical Research Centre, National Institute for Medical Research, Muheza, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Emmanuel W Kaindoa
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania
| | - Salum A Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
| | - Najat F Kahamba
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Luca Nelli
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Charles Wondji
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
- Department of Medical Entomology, Centre for Research in Infectious Diseases (CRID), Yaoundé 5, Cameroon
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg, South Africa
- Centre for Emerging Zoonotic & Parasitic Diseases, National Institute for Communicable Diseases, A Division of the National Health Laboratory Service, Johannesburg, South Africa
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Heather M Ferguson
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Francesco Baldini
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, P.O. Box 53, Ifakara, Tanzania.
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, P.O. Box 447, Arusha, Tanzania.
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Oruni A, Lynd A, Njoroge H, Onyige I, van’t Hof AE, Matovu E, Donnelly MJ. Pyrethroid resistance and gene expression profile of a new resistant An. gambiae colony from Uganda reveals multiple resistance mechanisms and overexpression of Glutathione-S-Transferases linked to survival of PBO-pyrethroid combination. Wellcome Open Res 2024; 9:13. [PMID: 38813466 PMCID: PMC11134160 DOI: 10.12688/wellcomeopenres.19404.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2024] [Indexed: 05/31/2024] Open
Abstract
Background The effectiveness of long-lasting insecticidal nets (LLINs) are being threatened by growing resistance to pyrethroids. To restore their efficacy, a synergist, piperonyl butoxide (PBO) which inhibits cytochrome P450s has been incorporated into pyrethroid treated nets. A trial of PBO-LLINs was conducted in Uganda from 2017 and we attempted to characterize mechanisms of resistance that could impact intervention efficacy. Methods We established an Anopheles gambiae s.s colony in 2018 using female mosquitoes collected from Busia district in eastern Uganda. We first assessed the phenotypic resistance profile of this colony using WHO tube and net assays using a deltamethrin dose-response approach. The Busia colony was screened for known resistance markers and RT-qPCR targeting 15 genes previously associated with insecticide resistance was performed. Results The Busia colony had very high resistance to deltamethrin, permethrin and DDT. In addition, the colony had moderate resistance to alpha-cypermethrin and lambda-cyhalothrin but were fully susceptible to bendiocarb and fenitrothion. Exposure to PBO in combination with permethrin and deltamethrin resulted in higher mortality rates in both net and tube assays, with a higher mortality observed in net assays than tube assays. The kdr marker, Vgsc-995S was at very high frequency (91.7-98.9%) whilst the metabolic markers Coeae1d and Cyp4j5-L43F were at very low (1.3% - 11.5%) and moderate (39.5% - 44.7%) frequencies respectively. Our analysis showed that gene expression pattern in mosquitoes exposed to deltamethrin, permethrin or DDT only were similar in comparison to the susceptible strain and there was significant overexpression of cytochrome P450s, glutathione-s-transferases (GSTs) and carboxyl esterases (COEs). However, mosquitoes exposed to both PBO and pyrethroid strikingly and significantly only overexpressed closely related GSTs compared to unexposed mosquitoes while major cytochrome P450s were underexpressed. Conclusions The high levels of pyrethroid resistance observed in Busia appears associated with a wide range of metabolic gene families.
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Affiliation(s)
- Ambrose Oruni
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, L3 5QA, UK
- College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Central Region, Uganda
| | - Amy Lynd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, L3 5QA, UK
| | - Harun Njoroge
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, L3 5QA, UK
- Centre for Global Health Research, Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Ismail Onyige
- Infectious Diseases Research Collaboration, Kampala, Central Region, Uganda
| | - Arjen E. van’t Hof
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, L3 5QA, UK
| | - Enock Matovu
- College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala, Central Region, Uganda
| | - Martin J. Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, Merseyside, L3 5QA, UK
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Friedman-Klabanoff DJ, Adu-Gyasi D, Asante KP. Malaria prevention in children: an update. Curr Opin Pediatr 2024; 36:164-170. [PMID: 38299986 PMCID: PMC10932812 DOI: 10.1097/mop.0000000000001332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2024]
Abstract
PURPOSE OF REVIEW Malaria cases and deaths decreased from 2000 to 2015 but remain increased since 2019. Several new developments and strategies could help reverse this trend. The purpose of this review is to discuss new World Health Organization (WHO) guidelines and recent research on malaria prevention in children. RECENT FINDINGS Fifteen countries have now rolled out seasonal malaria chemoprophylaxis (SMC) in children at highest risk for severe malaria, and new WHO recommendations provide more flexibility for SMC implementation in terms of target age groups, geographic region, and number of cycles. Recent studies confirm that malaria burden in school aged children, and their contribution to transmission, is high. New guidelines permit expanded chemoprevention options for these children. Two vaccines have been approved for use in malaria endemic countries, RTS,S/AS01 E and R21/Matrix-M. Additionally, pyrethroid-chlorfenapyr bed nets are being deployed to combat resistant mosquitoes. SUMMARY While challenges remain in malaria control towards elimination, new guidelines and recently approved vaccines offer hope. Monitoring for continued vaccine and chemoprevention effectiveness, and for possible epidemiologic shifts in severe malaria presentation and deaths as additional prevention efforts roll out will be paramount.
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Affiliation(s)
- DeAnna J Friedman-Klabanoff
- Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Dennis Adu-Gyasi
- Kintampo Health Research Centre, Research and Development Division, Ghana Health Service, Kintampo North Municipality, Bono East Region, Ghana
- Centre for Research in Applied Biology, School of Sciences, University of Energy and Natural Resources, Sunyani, Bono Region, Ghana, West Africa
| | - Kwaku Poku Asante
- Kintampo Health Research Centre, Research and Development Division, Ghana Health Service, Kintampo North Municipality, Bono East Region, Ghana
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Gilleran JA, Ashraf K, Delvillar M, Eck T, Fondekar R, Miller EB, Hutchinson A, Dong A, Seitova A, De Souza ML, Augeri D, Halabelian L, Siekierka J, Rotella DP, Gordon J, Childers WE, Grier MC, Staker BL, Roberge JY, Bhanot P. Structure-Activity Relationship of a Pyrrole Based Series of PfPKG Inhibitors as Anti-Malarials. J Med Chem 2024; 67:3467-3503. [PMID: 38372781 DOI: 10.1021/acs.jmedchem.3c01795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Controlling malaria requires new drugs against Plasmodium falciparum. The P. falciparum cGMP-dependent protein kinase (PfPKG) is a validated target whose inhibitors could block multiple steps of the parasite's life cycle. We defined the structure-activity relationship (SAR) of a pyrrole series for PfPKG inhibition. Key pharmacophores were modified to enable full exploration of chemical diversity and to gain knowledge about an ideal core scaffold. In vitro potency against recombinant PfPKG and human PKG were used to determine compound selectivity for the parasite enzyme. P. berghei sporozoites and P. falciparum asexual blood stages were used to assay multistage antiparasitic activity. Cellular specificity of compounds was evaluated using transgenic parasites expressing PfPKG carrying a substituted "gatekeeper" residue. The structure of PfPKG bound to an inhibitor was solved, and modeling using this structure together with computational tools was utilized to understand SAR and establish a rational strategy for subsequent lead optimization.
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Affiliation(s)
- John A Gilleran
- Rutgers Molecular Design and Synthesis Core, Office for Research, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, United States
| | - Kutub Ashraf
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, 225 Warren Street, Newark, New Jersey 07103, United States
| | - Melvin Delvillar
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, 225 Warren Street, Newark, New Jersey 07103, United States
| | - Tyler Eck
- Department of Chemistry and Biochemistry and Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, New Jersey 07043, United States
| | - Raheel Fondekar
- Rutgers Molecular Design and Synthesis Core, Office for Research, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, United States
- Rutgers School of Pharmacy, 160 Frelinghuysen Road, Piscataway, New Jersey 08854, United States
| | - Edward B Miller
- Schrödinger, Inc., 1540 Broadway, 24th Floor, New York, New York 10036, United States
| | - Ashley Hutchinson
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Aiping Dong
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Alma Seitova
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
| | - Mariana Laureano De Souza
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, 225 Warren Street, Newark, New Jersey 07103, United States
| | - David Augeri
- Rutgers Molecular Design and Synthesis Core, Office for Research, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, United States
- Schrödinger, Inc., 1540 Broadway, 24th Floor, New York, New York 10036, United States
| | - Levon Halabelian
- Structural Genomics Consortium, University of Toronto, Toronto, Ontario M5G 1L7, Canada
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
| | - John Siekierka
- Department of Chemistry and Biochemistry and Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, New Jersey 07043, United States
| | - David P Rotella
- Department of Chemistry and Biochemistry and Sokol Institute of Pharmaceutical Life Sciences, Montclair State University, Montclair, New Jersey 07043, United States
| | - John Gordon
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, Pennsylvania 19140, United States
| | - Wayne E Childers
- Moulder Center for Drug Discovery Research, Temple University School of Pharmacy, Philadelphia, Pennsylvania 19140, United States
| | - Mark C Grier
- Rutgers Molecular Design and Synthesis Core, Office for Research, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, United States
| | - Bart L Staker
- Seattle Structural Genomics Center for Infectious Disease, Seattle, Washington 98109, United States
- Center for Global Infectious Disease Research, Seattle Children's Research Institute, Seattle, Washington 98109, United States
| | - Jacques Y Roberge
- Rutgers Molecular Design and Synthesis Core, Office for Research, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854, United States
| | - Purnima Bhanot
- Department of Microbiology, Biochemistry and Molecular Genetics, Rutgers New Jersey Medical School, 225 Warren Street, Newark, New Jersey 07103, United States
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9
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Lucas ER, Nagi SC, Kabula B, Batengana B, Kisinza W, Egyir-Yawson A, Essandoh J, Dadzie S, Chabi J, Van't Hof AE, Rippon EJ, Pipini D, Harding NJ, Dyer NA, Clarkson CS, Miles A, Weetman D, Donnelly MJ. Copy number variants underlie the major selective sweeps in insecticide resistance genes in Anopheles arabiensis from Tanzania. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.11.583874. [PMID: 38559088 PMCID: PMC10979859 DOI: 10.1101/2024.03.11.583874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
To keep ahead of the evolution of resistance to insecticides in mosquitoes, national malaria control programmes must make use of a range of insecticides, both old and new, while monitoring resistance mechanisms. Knowledge of the mechanisms of resistance remains limited in Anopheles arabiensis, which in many parts of Africa is of increasing importance because it is apparently less susceptible to many indoor control interventions. Furthermore, comparatively little is known in general about resistance to non-pyrethroid insecticides such as pirimiphos-methyl (PM), which are crucial for effective control in the context of resistance to pyrethroids. We performed a genome-wide association study to determine the molecular mechanisms of resistance to deltamethrin (commonly used in bednets) and PM, in An. arabiensis from two regions in Tanzania. Genomic regions of positive selection in these populations were largely driven by copy number variants (CNVs) in gene families involved in resistance to these two insecticides. We found evidence of a new gene cluster involved in resistance to PM, identifying a strong selective sweep tied to a CNV in the Coeae2g-Coeae6g cluster of carboxylesterase genes. Using complementary data from An. coluzzii in Ghana, we show that copy number at this locus is significantly associated with PM resistance. Similarly, for deltamethrin, resistance was strongly associated with a novel CNV allele in the Cyp6aa / Cyp6p cluster. Against this background of metabolic resistance, target site resistance was very rare or absent for both insecticides. Mutations in the pyrethroid target site Vgsc were at very low frequency in Tanzania, yet combining these samples with three An. arabiensis individuals from West Africa revealed a startling diversity of evolutionary origins of target site resistance, with up to 5 independent origins of Vgsc-995 mutations found within just 8 haplotypes. Thus, despite having been first recorded over 10 years ago, Vgsc resistance mutations in Tanzanian An. arabiensis have remained at stable low frequencies. Overall, our results provide a new copy number marker for monitoring resistance to PM in malaria mosquitoes, and reveal the complex picture of resistance patterns in An. arabiensis.
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Affiliation(s)
- Eric R Lucas
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Sanjay C Nagi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Bilali Kabula
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | - Bernard Batengana
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | - William Kisinza
- National Institute for Medical Research, Amani Research Centre, P.O. Box 81, Muheza, Tanzania
| | | | - John Essandoh
- Department of Biomedical Sciences, University of Cape Coast, Cape Coast, Ghana
| | - Sam Dadzie
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Joseph Chabi
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Accra, Ghana
| | - Arjen E Van't Hof
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Branišovská 31, 370 05 České Budějovice, Czech Republic
| | - Emily J Rippon
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Dimitra Pipini
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Nicholas J Harding
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Naomi A Dyer
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Chris S Clarkson
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - Alistair Miles
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
| | - Martin J Donnelly
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK
- Wellcome Sanger Institute, Hinxton, Cambridge CB10 1SA, United Kingdom
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10
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Mosha JF, Matowo NS, Kulkarni MA, Messenger LA, Lukole E, Mallya E, Aziz T, Kaaya R, Shirima BA, Isaya G, Taljaard M, Hashim R, Martin J, Manjurano A, Kleinschmidt I, Mosha FW, Rowland M, Protopopoff N. Effectiveness of long-lasting insecticidal nets with pyriproxyfen-pyrethroid, chlorfenapyr-pyrethroid, or piperonyl butoxide-pyrethroid versus pyrethroid only against malaria in Tanzania: final-year results of a four-arm, single-blind, cluster-randomised trial. THE LANCET. INFECTIOUS DISEASES 2024; 24:87-97. [PMID: 37776879 DOI: 10.1016/s1473-3099(23)00420-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Revised: 05/31/2023] [Accepted: 06/20/2023] [Indexed: 10/02/2023]
Abstract
BACKGROUND New classes of long-lasting insecticidal nets (LLINs) containing two active ingredients have been recently recommended by WHO in areas where malaria vectors are resistant to pyrethroids. This policy was based on evidence generated by the first 2 years of our recently published trial in Tanzania. In this Article, we report the final third-year trial findings, which are necessary for assessing the long-term effectiveness of new classes of LLIN in the community and the replacement intervals required. METHODS A third year of follow-up of a four-arm, single-blind, cluster-randomised controlled trial of dual active ingredient LLINs was conducted between July 14, 2021, and Feb 10, 2022, in Misungwi, Tanzania. Restricted randomisation was used to assign 84 clusters to the four LLIN groups (1:1:1:1) to receive either standard pyrethroid (PY) LLINs (reference), chlorfenapyr-PY LLINs, pyriproxyfen-PY LLINs, or piperonyl butoxide (PBO)-PY LLINs. All households received one LLIN for every two people. Data collection was done in consenting households in the cluster core area with at least one child between 6 months and 15 years of age who permanently resided in the selected household. Exclusion criteria were householders absent during the visit, living in the cluster buffer area, no adult caregiver capable of giving informed consent, or eligible children who were severely ill. Field staff and study participants were masked to allocation, and those analysing data were not. The primary 24-month endpoint was reported previously; here, we present the secondary outcome, malaria infection prevalence in children at 36 months post LLIN distribution, reported in the intention-to-treat analysis. The trial was registered with ClinicalTrials.gov (NCT03554616) and is now complete. FINDINGS Overall usage of study nets was 1023 (22·3%) of 4587 people at 36 months post distribution. In the standard PY LLIN group, malaria infection was prevalent in 407 (37·4%) of 1088 participants, compared with 261 (22·8%) of 1145 in the chlorfenapyr-PY LLIN group (odds ratio 0·57, 95% CI 0·38-0·86; p=0·0069), 338 (32·2%) of 1048 in the PBO-PY LLIN group (0·95, 0·64-1·42; p=0·80), and 302 (28·8%) of 1050 in the pyriproxyfen-PY LLIN group (0·82, 0·55-1·23; p=0·34). None of the participants or caregivers reported side-effects. INTERPRETATION Despite low coverage, the protective efficacy against malaria offered by chlorfenapyr-PY LLINs was superior to that provided by standard PY LLINs over a 3-year LLIN lifespan. Appropriate LLIN replacement strategies to maintain adequate usage of nets will be necessary to maximise the full potential of these nets. FUNDING Department for International Development, UK Medical Research Council, Wellcome Trust, Department of Health and Social Care, and Bill & Melinda Gates Foundation via the Innovative Vector Control Consortium.
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Affiliation(s)
- Jacklin F Mosha
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Nancy S Matowo
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
| | - Manisha A Kulkarni
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK; Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV, USA
| | - Eliud Lukole
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Elizabeth Mallya
- Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Tatu Aziz
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Robert Kaaya
- Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Boniface A Shirima
- Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Gladness Isaya
- Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Monica Taljaard
- School of Epidemiology and Public Health, University of Ottawa, Ottawa, ON, Canada; Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Ramadhan Hashim
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Jacklin Martin
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania; Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Alphaxard Manjurano
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Immo Kleinschmidt
- Medical Research Council Tropical Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, UK; Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa; Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Franklin W Mosha
- Department of Parasitology, Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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11
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Protopopoff N, Mosha JF, Messenger LA, Lukole E, Charlwood JD, Wright A, Kessy E, Manjurano A, Mosha FW, Kleinschmidt I, Rowland M. Effectiveness of piperonyl butoxide and pyrethroid-treated long-lasting insecticidal nets (LLINs) versus pyrethroid-only LLINs with and without indoor residual spray against malaria infection: third year results of a cluster, randomised controlled, two-by-two factorial design trial in Tanzania. Malar J 2023; 22:294. [PMID: 37789389 PMCID: PMC10548685 DOI: 10.1186/s12936-023-04727-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Accepted: 09/25/2023] [Indexed: 10/05/2023] Open
Abstract
BACKGROUND After decades of success in reducing malaria through the scale-up of pyrethroid long-lasting insecticidal nets (LLINs), the decline in the malaria burden has stalled, coinciding with the rapid spread of pyrethroid resistance. In a previously reported study, nets treated with a pyrethroid and a synergist, piperonyl butoxide (PBO), demonstrated superior efficacy compared to standard pyrethroid LLINs (std-LLINs) against malaria. Evidence was used to support the public health recommendation of PBO-Pyrethroid-LLIN by the World Health Organization in 2018. This study looks at the third year of rollout of these nets in Muleba district, Tanzania to inform whether policy guidelines need to be updated. METHODS A four-group cluster randomized trial (CRT) using a two-by-two factorial design was carried out between January 2014 and December 2017. A total of 48 clusters, were randomized in a 1:1:1:1 ratio to the following treatment groups, each intervention being provided once in 2015: 1/std-LLIN; 2/PBO-pyrethroid LLIN; 3/std-LLIN + Indoor Residual Spraying (IRS) and 4/PBO-Pyrethroid-LLIN + IRS. During the third year follow-up, malaria infection prevalence in 80 children per cluster, aged 6 months to 14 years, was measured at 28- and 33-months post-intervention and analysed as intention-to-treat (ITT) and per protocol (PP). Mosquito collections were performed monthly in all clusters, using CDC light traps in 7 randomly selected houses per cluster. RESULTS At 28 and 33 months, study net usage among household participants was only 47% and 31%, respectively. In ITT analysis, after 28 months malaria infection prevalence among 7471 children was 80.9% in the two std-LLIN groups compared to 69.3% in the two PBO-Pyrethroid-LLIN (Odds Ratio: 0.45, 95% Confidence Interval: 0.21-0.95, p-value: 0.0364). After 33 months the effect was weaker in the ITT analysis (prevalence 59.6% versus 49.9%, OR: 0.60, 95%CI:0.32-1.13, p-value: 0.1131) but still evident in the PP analysis (57.2% versus 44.2%, OR: 0.34, 95%CI: 0.16-0.71, p-value: 0.0051). Mean number of Anopheles per night collected per house was similar between PBO-Pyrethroid-LLIN groups (5.48) and std-LLIN groups (5.24) during the third year. CONCLUSIONS Despite low usage of PBO- Pyrethroid LLIN, a small impact of those nets on malaria infection prevalence was still observed in the 3rd year with the most protection offered to children still using them. To maximize impact, it is essential that net re-distribution cycles are aligned with this LLIN lifespan to maintain maximum coverage. TRIAL REGISTRATION The trial was registered with ClinicalTrials.gov (registration number NCT02288637).
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Affiliation(s)
- Natacha Protopopoff
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
| | - Jacklin F Mosha
- Mwanza Medical Research Centre, National Institute for Medical Research, Mwanza, Tanzania
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Eliud Lukole
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
- Mwanza Medical Research Centre, National Institute for Medical Research, Mwanza, Tanzania
| | - Jacques D Charlwood
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Alexandra Wright
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Enock Kessy
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Alphaxard Manjurano
- Mwanza Medical Research Centre, National Institute for Medical Research, Mwanza, Tanzania
| | - Franklin W Mosha
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Immo Kleinschmidt
- MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
- School of Pathology, Faculty of Health Sciences, University of Witwatersrand, Johannesburg, South Africa
- Southern African Development Community Malaria Elimination Eight Secretariat, Windhoek, Namibia
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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12
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Djènontin A, Alfa D, Bouraima A, Soares C, Dahounto A, Cornélie S, Egrot M, Damien G, Remoué F, Sagna AB, Moiroux N, Pennetier C. Durability of the deltamethrin-treated polypropylene long-lasting net LifeNet® in a pyrethroid resistance area in south western Benin: A phase III trial. PLoS One 2023; 18:e0291755. [PMID: 37729177 PMCID: PMC10511067 DOI: 10.1371/journal.pone.0291755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 09/05/2023] [Indexed: 09/22/2023] Open
Abstract
BACKGROUND Long-lasting insecticidal bed nets (LLINs) are a key measure for preventing malaria and their evaluation is coordinated by the World Health Organization Pesticide Evaluation Scheme (WHOPES). LifeNet® was granted WHOPES time-limited interim recommendation in 2011 after successful Phase I and Phase II evaluations. Here, we evaluated the durability and community acceptance of LifeNet® in a Phase III trial from June 2014 to June 2017 in Benin rural area. METHODS A prospective longitudinal, cluster-randomized, controlled trial with households as the unit of observation was designed to assess the performance of LifeNet® over a three-year period, using a WHOPES fully recommended LLIN (PermaNet® 2.0) as a positive control. The primary outcomes were the bioassay performance using WHO cone assays and tunnel tests, the insecticide content and physical integrity. RESULTS At baseline, 100% of LLINs were within the tolerance limits of their target deltamethrin concentrations. By 36 months only 17.3% of LifeNet® and 8.5% of PermaNet® LLINs still were within their target deltamethrin concentrations. Despite these low rates, 100% of both LLINs meet WHO efficacy criteria (≥ 80% mortality or ≥ 95% knockdown or tunnel test criteria of ≥ 80% mortality or ≥ 90% blood-feeding inhibition) after 36 months using WHO cone bio-assays and tunnel tests. The proportion of LLINs in good physical condition was 33% for LifeNet® and 29% for PermaNet® after 36 months. After 36 M the survivorship was 21% and 26% for LifeNet® and PermaNet® respectively. Although both LLINs were well accepted by the population, complaints of side effects were significantly higher among LifeNet® users than PermaNet® ones. CONCLUSION LifeNet® LLINs did meet WHO criteria for bio-efficacy throughout the study period and were well accepted by the population. This is an important step towards getting a full WHO recommendation for use in malaria endemic countries.
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Affiliation(s)
- Armel Djènontin
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Daleb Alfa
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Aziz Bouraima
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Christophe Soares
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Amal Dahounto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Sylvie Cornélie
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - Marc Egrot
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | - Georgia Damien
- Centre de Recherche Pour la Lutte Contre les Maladies Infectieuses Tropicales (CReMIT), Université D’Abomey-Calavi (UAC), Cotonou, Bénin
| | - Franck Remoué
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
| | | | | | - Cédric Pennetier
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
- MIVEGEC, Univ Montpellier, CNRS, IRD, Montpellier, France
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13
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Duke T. Randomised controlled trials in child and adolescent health in 2023. Arch Dis Child 2023; 108:709-714. [PMID: 37474280 DOI: 10.1136/archdischild-2023-326046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 07/12/2023] [Indexed: 07/22/2023]
Abstract
In the year July 2022 to June 2023 there were 501 publications from randomised controlled trials (RCTs) in child and adolescent health in developing countries identified through a standardised search strategy that has been going for 20 years. This year, trials addressed the widest range of diseases and conditions that affect the health, development and well-being of children, newborns, adolescents and mothers. RCTs reflected old, neglected and new problems, the changing epidemiology of child health, social and economic circumstances in many countries, local and global priorities of low-income and middle-income countries, environmental causes of poor child health, and inequities. The RCTs tested new and refined treatments, diagnostics, vaccines, holistic management, and prevention approaches, and explored many outcomes, including mortality, nutrition, psychosocial measures, and neurodevelopment. The studies were conducted in numerous hospitals and healthcare clinics, schools, and communities, including among some of the world's most disadvantaged populations in humanitarian and refugee emergencies. Some studies are of the highest quality, and others fall short. Many RCTs will influence guidelines, practice and policies for years to come.
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Affiliation(s)
- Trevor Duke
- Department of Paediatrics, University of Melbourne, and Intensive Care Unit, The Royal Children's Hospital, Melbourne, Victoria, Australia
- Child Health, School of Medicine and Health Sciences, University of Papua New Guinea, Port Moresby, Papua New Guinea
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14
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Yovogan B, Adoha CJ, Akinro B, Accrombessi M, Dangbénon E, Sidick A, Ossè R, Padonou GG, Messenger LA, Fassinou A, Sagbohan HW, Agbangla C, Djènontin A, Odjo EM, Ngufor C, Cook J, Protopopoff N, Sovi A, Akogbéto MC. Field performance of three mosquito collection methods for assessing the entomological efficacy of dual-active ingredient long-lasting insecticidal nets. Sci Rep 2023; 13:12263. [PMID: 37507478 PMCID: PMC10382560 DOI: 10.1038/s41598-023-39558-9] [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: 03/14/2023] [Accepted: 07/27/2023] [Indexed: 07/30/2023] Open
Abstract
Selection of mosquito collection methods is of crucial importance to evaluate the impact of vector control tools on entomological outcomes. During a cluster randomised control trial evaluating the relative efficacy of two dual-active ingredient (a.i.) long-lasting insecticidal nets (LLINs) compared to pyrethroid-only LLINs, we assessed the performance of different mosquito collection methods: Human landing catches (HLC), Centers for Disease Control and Prevention (CDC) light traps, and pyrethrum spray catches (PSC). Anopheles mosquitoes were collected using three collection methods in 4 houses, in each of the 60 trial clusters at baseline and every quarter for 24 months using PSCs and HLCs, while CDC light traps were performed during two quarters only. Mean density of vectors collected per method per night was the highest with HLCs (15.9), followed by CDC light traps (6.8); with PSCs (1.1) collecting 10 times less mosquitoes than HLCs. All three collection methods collected fewer mosquitoes in the Interceptor G2® dual a.i. arm, compared to the other trial arms, although only HLCs and PSCs demonstrated strong evidence of this due to a greater number of collection rounds undertaken, than CDC light traps. The broadly similar results regarding the differential impact of the two dual a.i. LLINs showed by the three collection methods suggest that the more ethically acceptable, cheaper, and logistically simpler methods such as CDC light traps could be prioritised for use in large community trials for measuring the efficacy of vector control tools.
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Affiliation(s)
- Boulais Yovogan
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin.
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
| | - Constantin J Adoha
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Bruno Akinro
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Manfred Accrombessi
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | | | | | - Razaki Ossè
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Ecole de Gestion et d'Exploitation des Systèmes d'Elevage, Université Nationale d'Agriculture, Kétou, Benin
| | - Gil G Padonou
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Louisa A Messenger
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
- Department of Environmental and Occupational Health, School of Public Health, University of Nevada, Las Vegas, NV, 89154, USA
| | - Arsène Fassinou
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Hermann W Sagbohan
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Clément Agbangla
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
| | - Armel Djènontin
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Esdras M Odjo
- Faculté des Sciences et Techniques, Université d'Abomey-Calavi, Abomey-Calavi, Benin
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
| | - Corine Ngufor
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Jackie Cook
- Medical Research Council (MRC) International Statistics and Epidemiology, Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Natacha Protopopoff
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Arthur Sovi
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
- Faculty of Infectious and Tropical Diseases, Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK.
- Faculté d'Agronomie, Université de Parakou, Parakou, Benin.
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15
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Syme T, Nounagnon J, N'dombidjé B, Gbegbo M, Agbevo A, Ahoga J, Ngufor C. Can the performance of pyrethroid-chlorfenapyr nets be reduced when combined with pyrethroid-piperonyl butoxide (PBO) nets? Malar J 2023; 22:214. [PMID: 37480030 PMCID: PMC10362717 DOI: 10.1186/s12936-023-04648-6] [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: 03/30/2023] [Accepted: 07/14/2023] [Indexed: 07/23/2023] Open
Abstract
BACKGROUND Pyrethroid-chlorfenapyr (CFP) and pyrethroid-piperonyl butoxide (PBO) nets are being scaled across endemic countries to improve control of malaria transmitted by pyrethroid-resistant mosquitoes. CFP is a pro-insecticide requiring activation by mosquito cytochrome P450 monooxygenase enzymes (P450s) while PBO improves pyrethroid potency by inhibiting the action of these enzymes in pyrethroid-resistant mosquitoes. The inhibitory action of PBO against P450s may thus reduce the efficacy of pyrethroid-CFP nets when applied inside the same household as pyrethroid-PBO nets. METHODS Two experimental hut trials were performed to evaluate the entomological impact of two different types of pyrethroid-CFP ITN (Interceptor® G2, PermaNet® Dual) when applied alone and in combination with pyrethroid-PBO ITNs (DuraNet® Plus, PermaNet® 3.0) against a pyrethroid-resistant vector population in southern Benin. In both trials, all net types were tested as single and double net treatments. Bioassays were also performed to assess the resistance profile of the vector population at the hut site and investigate interactions between CFP and PBO. RESULTS The vector population was susceptible to CFP but exhibited a high intensity of pyrethroid resistance that was overcame by PBO pre-exposure. Vector mortality was significantly lower in huts with combinations of pyrethroid-CFP nets plus pyrethroid-PBO nets compared to huts with two pyrethroid-CFP nets (74% vs. 85% for Interceptor® G2 and 57% vs. 83% for PermaNet® Dual, p < 0.001). PBO pre-exposure reduced the toxicity of CFP in bottle bioassays suggesting this effect may be partly attributable to antagonism between CFP and PBO. Higher levels of vector mortality were observed in huts with net combinations that included pyrethroid-CFP nets compared to those that did not and highest mortality was achieved when pyrethroid-CFP nets were applied alone as two nets together (83-85%). CONCLUSIONS This study shows evidence of a reduced performance of pyrethroid-CFP nets when combined with pyrethroid-PBO ITNs compared to when applied alone and higher efficacy with net combinations that included pyrethroid-CFP nets. These findings suggest that in similar contexts, prioritizing distribution of pyrethroid-CFP nets over other net types would maximize vector control impact.
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Affiliation(s)
- Thomas Syme
- London School of Hygiene & Tropical Medicine, London, UK.
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
| | - Judicaël Nounagnon
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Boris N'dombidjé
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Martial Gbegbo
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Abel Agbevo
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Juniace Ahoga
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin
| | - Corine Ngufor
- London School of Hygiene & Tropical Medicine, London, UK.
- Centre de Recherche Entomologique de Cotonou, Cotonou, Benin.
- Pan African Malaria Vector Research Consortium (PAMVERC), Cotonou, Benin.
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16
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Zinszer K, Talisuna AO. Fighting insecticide resistance in malaria control. THE LANCET. INFECTIOUS DISEASES 2023; 23:138-139. [PMID: 36174593 DOI: 10.1016/s1473-3099(22)00518-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 07/27/2022] [Indexed: 02/01/2023]
Affiliation(s)
- Kate Zinszer
- School of Public Health, University of Montreal, Montreal, QC H3N 1X9, Canada; Centre for Public Health Research, Montreal, QC, Canada.
| | - Ambrose Otau Talisuna
- Emergency Preparedness and Response Cluster, WHO, Regional Office for Africa, Brazzaville, Congo
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