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Alafo C, Montoya LF, Martí-Soler H, Máquina M, Malheia A, Sacoor C, Abílio AP, Marrenjo D, Cuamba N, Galatas B, Aide P, Saúte F, Paaijmans KP. An evaluation of LLIN physical integrity and population attitudes towards net use, care and handling during the Magude project in southern Mozambique. Malar J 2024; 23:87. [PMID: 38532416 PMCID: PMC10967156 DOI: 10.1186/s12936-024-04910-5] [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: 12/20/2023] [Accepted: 03/18/2024] [Indexed: 03/28/2024] Open
Abstract
BACKGROUND The Magude Project assessed the feasibility of eliminating malaria in Magude district, a low transmission setting in southern Mozambique, using a package of interventions, including long-lasting insecticidal nets (LLINs). As the efficacy of LLINs depends in part on their physical integrity, this metric was quantified for Olyset® Nets post mass-distribution, in addition to net use, care and handling practices and other risk factors associated with net physical integrity. METHODS Nets were collected during a cross-sectional net evaluation, nine months after the Magude project commenced, which was 2 years after the nets were distributed by the National Malaria Control Programme (NMCP). The physical integrity of the nets was assessed by counting and sizing the holes at different positions on each net. A structured questionnaire was administered to assess how the selected net was used and treated (care, wash and repair). Net bio-efficacy was assessed following the standard World Health Organization (WHO) cone bioassay procedures. RESULTS Out of the 170 Olyset® Nets included in the analysis, 63.5% had been used the night before. The main reason for not using a net was the notion that there were no mosquitoes present. The average number of people using each net was 1.79. Two thirds of the nets had only been washed once or twice since distribution. Most nets (80.9%) were holed and 18% were torn, but none of the risk factors were significantly associated with net integrity, except for presence of mice in the household. Less than half of the participants noticed holes in holed nets, and of those only 38.6% attempted to repair those. None of the six nets that were tested for bio-efficacy passed the WHO threshold of 80% mosquito mortality. CONCLUSION Overall the majority of Olyset® Nets were in serviceable condition two years post-distribution, but their insecticidal effect may have been lost. This study-together with previous evidence on suboptimal access to and use of LLINs in Magude district-highlights that LLINs as an intervention could have been optimized during the Magude project to achieve maximum intervention impact.
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Affiliation(s)
- Celso Alafo
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
| | - Lucia Fernandez Montoya
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
- ISGlobal, Barcelona, Spain
| | | | - Mara Máquina
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
| | - Arlindo Malheia
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
| | - Charfudin Sacoor
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
| | - Ana Paula Abílio
- Instituto Nacional da Saúde, Ministério da Saúde, Maputo, Mozambique
| | - Dulcisaria Marrenjo
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
| | - Nelson Cuamba
- Programa Nacional de Controlo da Malária, Ministério da Saúde, Maputo, Mozambique
- PMI VectorLink Project, Abt Associates Inc., Maputo, Mozambique
| | - Beatriz Galatas
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
- ISGlobal, Barcelona, Spain
- Global Malaria Program, World Health Organization, Geneva, Switzerland
| | - Pedro Aide
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
- Instituto Nacional da Saúde, Ministério da Saúde, Maputo, Mozambique
| | - Francisco Saúte
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique
| | - Krijn P Paaijmans
- Centro de Investigação em Saúde de Manhiça (CISM), Fundação Manhiça, Maputo, Mozambique.
- ISGlobal, Barcelona, Spain.
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ, USA.
- Simon A. Levin Mathematical, Computational and Modeling Sciences Center, Arizona State University, Tempe, AZ, USA.
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Syahrani L, Asih PBS, Bowolaksono A, Dwiranti A, Zubaidah S, Rozi IE, Permana DH, Bøgh C, Bangs MJ, Grieco JP, Achee NL, Lobo NF, Syafruddin D. Impact of a spatial repellent intervention on Anopheles kdr insecticide resistance allele in Sumba, Indonesia. Malar J 2024; 23:31. [PMID: 38254131 PMCID: PMC10802001 DOI: 10.1186/s12936-024-04841-1] [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: 10/15/2023] [Accepted: 01/05/2024] [Indexed: 01/24/2024] Open
Abstract
BACKGROUND The emergence of insecticide resistance and outdoor transmission in malaria-endemic areas underlines the urgent need to develop innovative tools, such as spatial repellents (SR), that may circumvent this residual transmission. With limited options for effective insecticides, regular resistance monitoring is warranted for selecting and using appropriate tools. This study evaluates the pyrethroid knockdown resistance (kdr) allele before and after implementing a transfluthrin-based spatial repellent (SR) intervention in placebo-treated clusters. METHODS This study looks at the frequency distribution of the kdr allele in Sumba Island from June 2015 to August 2018. Insecticide susceptibility tests were carried out on female Anopheles sp. aged 3-5 days against permethrin 21.5 μg/ml, deltamethrin 12.5 μg/ml, and transfluthrin 10 μg/ml using CDC bottle assay. PCR sequencing of representative samples from adult mosquito collections and insecticide tests revealed the presence of kdr mutations (L1014F and L1014S) in the VGSC gene. RESULTS A total of 12 Anopheles species, Anopheles tesselatus, Anopheles. aconitus, Anopheles barbirostris, Anopheles kochi, Anopheles annularis, Anopheles maculatus, Anopheles sundaicus, Anopheles flavirostris, Anopheles balabacensis, Anopheles indefinitus, Anopheles subpictus, and Anopheles vagus were analysed. Anopheles vagus and An. sundaicus predominated in the larval populations. Susceptibility assays for all insecticides identified fully susceptible phenotypes in all species examined. Anopheles increasing frequency of kdr mutant alleles during the 3 year SR deployment was observed in both SR-treated and placebo areas, a statistically significant increase occurred in each arm. However, it is unclear how significant SR is in causing the increase in mutant alleles. The L1014S, knockdown resistance east type (kdr-e) allele was detected for the first time among the mosquito samples in this study. The L1014F, knockdown resistance west type (kdr-w) allele and heteroduplex form (wild-type-mutant) were found in almost all Anopheles species examined, including An. vagus, An. aconitus, An. subpictus, An. tesselatus, An. annularis, An. flavirostris and An. sundaicus. CONCLUSION The presence of fully susceptible phenotypes over time, along with an increase in the frequency distribution of the L1014F/S mutations post-intervention, suggest drivers of resistance external to the study, including pyrethroid use in agriculture and long-lasting insecticidal nets (LLINs). However, this does not negate possible SR impacts that support resistance. More studies that enable the comprehension of possible SR-based drivers of resistance in mosquitoes need to be conducted.
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Affiliation(s)
- Lepa Syahrani
- Doctoral Program, Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
| | - Puji B S Asih
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia.
| | - Anom Bowolaksono
- Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
| | - Astari Dwiranti
- Department of Biology, Faculty of Mathematics and Natural Sciences, University of Indonesia, Depok, Indonesia
| | - Siti Zubaidah
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
| | - Ismail E Rozi
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Doctoral Program, Faculty of Medicine, University of Hasanuddin, Makassar, Indonesia
| | - Dendi H Permana
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Doctoral Program of Biomedical Sciences, Faculty of Medicine, University of Indonesia, Jakarta, Indonesia
| | - Claus Bøgh
- The Sumba Foundation, Public Health and Malaria Control, Sumba, Indonesia
| | - Michael J Bangs
- Public Health and Malaria Control, PT Freeport Indonesia, International SOS, Mimika, Indonesia
| | - John P Grieco
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Nicole L Achee
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Neil F Lobo
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Indiana, USA
| | - Din Syafruddin
- Eijkman Research Center for Molecular Biology, National Research and Innovation Agency (BRIN), Cibinong, Indonesia
- Department of Parasitology, Faculty of Medicine, Hasanuddin University, Makassar, Indonesia
- Hasanuddin University Medical Research Center (HUMRC), Makassar, Indonesia
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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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