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Fatou M, Müller P. 3D video tracking analysis reveals that mosquitoes pass more likely through holes in permethrin-treated than in untreated nets. Sci Rep 2024; 14:13598. [PMID: 38866869 PMCID: PMC11169678 DOI: 10.1038/s41598-024-63968-y] [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: 05/31/2023] [Accepted: 06/04/2024] [Indexed: 06/14/2024] Open
Abstract
In addition to killing, mosquito nets treated with permethrin have been claimed to repel mosquitoes, reducing their success in passing through a holed net. We have tested this hypothesis by tracking mosquitoes in a modified World Health Organization tunnel test. In the original assay, mosquitoes are released at one end of the tunnel and have to pass through a holed piece of net to reach the bait at the other end. The mosquitoes are left in the tunnel overnight, while mortality and feeding rates are scored the following morning. Since the original test does not reveal how mosquitoes move within the tunnel, we combined the tunnel with a 3D video camera system. We tracked susceptible and permethrin-resistant Anopheles gambiae s.s. as they moved in the tunnel and interacted with an untreated or a permethrin-treated net (Olyset Net®). Surprisingly, while permethrin increased the mortality and reduced blood-feeding rates, twice as many mosquitoes passed through the holes of the permethrin-treated net. The flight trajectories reveal that upon exposure to the permethrin-treated net, both mosquito colonies showed increased 'excitation', thereby augmenting their chance of getting through the holes in the net. The study underlines the complexity of behavioural modes of action of insecticides.
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Affiliation(s)
- Mathurin Fatou
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland.
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland.
| | - Pie Müller
- Swiss Tropical and Public Health Institute, Kreuzstrasse 2, 4123, Allschwil, Switzerland
- University of Basel, Petersplatz 1, 4001, Basel, Switzerland
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2
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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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Sadoine ML, Zinszer K, Liu Y, Gachon P, Fournier M, Dueymes G, Dorsey G, Llerena A, Namuganga JF, Nasri B, Smargiassi A. Predicting malaria risk considering vector control interventions under climate change scenarios. Sci Rep 2024; 14:2430. [PMID: 38286803 PMCID: PMC10824718 DOI: 10.1038/s41598-024-52724-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: 07/07/2023] [Accepted: 01/23/2024] [Indexed: 01/31/2024] Open
Abstract
Many studies have projected malaria risks with climate change scenarios by modelling one or two environmental variables and without the consideration of malaria control interventions. We aimed to predict the risk of malaria with climate change considering the influence of rainfall, humidity, temperatures, vegetation, and vector control interventions (indoor residual spraying (IRS) and long-lasting insecticidal nets (LLIN)). We used negative binomial models based on weekly malaria data from six facility-based surveillance sites in Uganda from 2010-2018, to estimate associations between malaria, environmental variables and interventions, accounting for the non-linearity of environmental variables. Associations were applied to future climate scenarios to predict malaria distribution using an ensemble of Regional Climate Models under two Representative Concentration Pathways (RCP4.5 and RCP8.5). Predictions including interaction effects between environmental variables and interventions were also explored. The results showed upward trends in the annual malaria cases by 25% to 30% by 2050s in the absence of intervention but there was great variability in the predictions (historical vs RCP 4.5 medians [Min-Max]: 16,785 [9,902-74,382] vs 21,289 [11,796-70,606]). The combination of IRS and LLIN, IRS alone, and LLIN alone would contribute to reducing the malaria burden by 76%, 63% and 35% respectively. Similar conclusions were drawn from the predictions of the models with and without interactions between environmental factors and interventions, suggesting that the interactions have no added value for the predictions. The results highlight the need for maintaining vector control interventions for malaria prevention and control in the context of climate change given the potential public health and economic implications of increasing malaria in Uganda.
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Affiliation(s)
- Margaux L Sadoine
- School of Public Health, Université de Montréal, Montreal, Quebec, Canada.
- Center for Public Health Research, Université de Montréal, Montreal, Quebec, Canada.
| | - Kate Zinszer
- School of Public Health, Université de Montréal, Montreal, Quebec, Canada
- Center for Public Health Research, Université de Montréal, Montreal, Quebec, Canada
| | - Ying Liu
- School of Public Health, Université de Montréal, Montreal, Quebec, Canada
- Center for Public Health Research, Université de Montréal, Montreal, Quebec, Canada
| | - Philippe Gachon
- ESCER (Étude et Simulation du Climat à l'Échelle Régionale) Centre, Université du Québec à Montréal, Montreal, Quebec, Canada
| | - Michel Fournier
- Department of Public Health, Montreal Regional, Montreal, Quebec, Canada
| | - Guillaume Dueymes
- ESCER (Étude et Simulation du Climat à l'Échelle Régionale) Centre, Université du Québec à Montréal, Montreal, Quebec, Canada
| | - Grant Dorsey
- University of California San Francisco, San Francisco, USA
| | - Ana Llerena
- Department of Earth and Atmospheric Sciences, Université du Québec à Montréal, Montreal, Quebec, Canada
| | | | - Bouchra Nasri
- School of Public Health, Université de Montréal, Montreal, Quebec, Canada
- Center for Public Health Research, Université de Montréal, Montreal, Quebec, Canada
| | - Audrey Smargiassi
- School of Public Health, Université de Montréal, Montreal, Quebec, Canada
- Center for Public Health Research, Université de Montréal, Montreal, Quebec, Canada
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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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Kibondo UA, Renju J, Lukole E, Mosha JF, Mosha FW, Manjurano A, Rowland M, Protopopoff N. Factors associated with malaria infection among children after distribution of PBO-pyrethroid synergist-treated nets and indoor residual spraying in north-western Tanzania. PLoS One 2023; 18:e0295800. [PMID: 38127909 PMCID: PMC10734997 DOI: 10.1371/journal.pone.0295800] [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: 06/07/2023] [Accepted: 11/29/2023] [Indexed: 12/23/2023] Open
Abstract
BACKGROUND After a decade of successful control, malaria is on the rise again. The prevalence of malaria in Tanzania has increased from 7% in 2017 to 8% in 2022 and reached 18% in Kagera region in the North West of Tanzania. Malaria vectors in Muleba district Kagera have high level of pyrethroid resistance. The aim of this paper is to explore factors associated with malaria infection prevalence in children aged 6 months to 14 years in Muleba, where Long Lasting Insecticidal Net (LLIN) combining a pyrethroid insecticide and synergist piperonyl butoxide (PBO) that counteract resistance in the mosquitoes, was first distributed under trial conditions in 2015. METHODS The trial was a community randomized control in which there were two malaria prevalence cross-sectional household surveys each year (June and December) from 2015 to 2017 in Muleba. In this study we conducted a secondary data analysis of the December surveys only. Multilevel Poisson regression analysis was used to assess factors associated with malaria infection. RESULTS A total of 10,941 children and 4,611 households were included in this study. Overall malaria prevalence was 35.8%, 53.3% and 54.4% in the year 2015, 2016 and 2017 respectively. Living in an area with standard LLIN as opposed to the novel PBO synergist LLIN, being a male child, above 5 years of age, living in a house with open eaves, living in house without IRS, having head of household with no formal education, lower socioeconomic status and survey year were associated with increased risk of malaria infection. CONCLUSIONS Using PBO LLIN reduced the risk of malaria infection. However, additional measures could further reduce malaria infection in areas of insecticide resistance such as housing improvement.
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Affiliation(s)
- Ummi Abdul Kibondo
- Vector Control Product Testing Unit (VCPTU) Ifakara Health Institute, Environmental Health, and Ecological Sciences, Bagamoyo, Tanzania
- Department of Epidemiology and Biostatistics, Institute of Public Health, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
| | - Jenny Renju
- Department of Epidemiology and Biostatistics, Institute of Public Health, Kilimanjaro Christian Medical University College (KCMUCo), Moshi, Tanzania
- The London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Eliud Lukole
- Kilimanjaro Christian Medical University College, Moshi, Tanzania
| | - Jacklin F. Mosha
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | | | - Alphaxard Manjurano
- National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Mark Rowland
- The London School of Hygiene and Tropical Medicine, London, United Kingdom
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Sadoine ML, Smargiassi A, Liu Y, Gachon P, Fournier M, Dueymes G, Namuganga JF, Dorsey G, Nasri B, Zinszer K. Differential Influence of Environmental Factors on Malaria Due to Vector Control Interventions in Uganda. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:7042. [PMID: 37998273 PMCID: PMC10671539 DOI: 10.3390/ijerph20227042] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 10/23/2023] [Accepted: 11/06/2023] [Indexed: 11/25/2023]
Abstract
BACKGROUND Few studies have explored how vector control interventions may modify associations between environmental factors and malaria. METHODS We used weekly malaria cases reported from six public health facilities in Uganda. Environmental variables (temperature, rainfall, humidity, and vegetation) were extracted from remote sensing sources. The non-linearity of environmental variables was investigated, and negative binomial regression models were used to explore the influence of indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) on associations between environmental factors and malaria incident cases for each site as well as pooled across the facilities, with or without considering the interaction between environmental variables and vector control interventions. RESULTS An average of 73.3 weekly malaria cases per site (range: 0-597) occurred between 2010 and 2018. From the pooled model, malaria risk related to environmental variables was reduced by about 35% with LLINs and 63% with IRS. Significant interactions were observed between some environmental variables and vector control interventions. There was site-specific variability in the shape of the environment-malaria risk relationship and in the influence of interventions (6 to 72% reduction in cases with LLINs and 43 to 74% with IRS). CONCLUSION The influence of vector control interventions on the malaria-environment relationship need to be considered at a local scale in order to efficiently guide control programs.
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Affiliation(s)
- Margaux L. Sadoine
- Department of Social and Preventive Medicine, School of Public Health, Université de Montréal, Montreal, QC H3N 1X9, Canada
- Center for Public Health Research, Université de Montréal, Montreal, QC H3N 1X9, Canada
| | - Audrey Smargiassi
- Center for Public Health Research, Université de Montréal, Montreal, QC H3N 1X9, Canada
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Montreal, QC H3T 1A8, Canada
| | - Ying Liu
- Center for Public Health Research, Université de Montréal, Montreal, QC H3N 1X9, Canada
- Department of Environmental and Occupational Health, School of Public Health, Université de Montréal, Montreal, QC H3T 1A8, Canada
| | - Philippe Gachon
- ESCER (Étude et Simulation du Climat à l’Échelle Régionale) Centre, Université du Québec à Montréal, Montreal, QC H2L 2C4, Canada
| | - Michel Fournier
- Montreal Regional Department of Public Health, Montreal, QC H2L 1M3, Canada
| | - Guillaume Dueymes
- ESCER (Étude et Simulation du Climat à l’Échelle Régionale) Centre, Université du Québec à Montréal, Montreal, QC H2L 2C4, Canada
| | | | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, CA 94143, USA
| | - Bouchra Nasri
- Department of Social and Preventive Medicine, School of Public Health, Université de Montréal, Montreal, QC H3N 1X9, Canada
- Center for Public Health Research, Université de Montréal, Montreal, QC H3N 1X9, Canada
| | - Kate Zinszer
- Department of Social and Preventive Medicine, School of Public Health, Université de Montréal, Montreal, QC H3N 1X9, Canada
- Center for Public Health Research, Université de Montréal, Montreal, QC H3N 1X9, Canada
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da Silva Ferreira Lima AC, Galardo AKR, Müller JN, de Andrade Corrêa APS, Ribeiro KAN, Silveira GA, Hijjar AV, Soares da Roch Bauzer LG, Lima JBP. Evaluation of Long-lasting insecticidal nets (LLINs) for malaria control in an endemic area in Brazil. Parasit Vectors 2023; 16:162. [PMID: 37173754 PMCID: PMC10182611 DOI: 10.1186/s13071-023-05759-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Accepted: 03/29/2023] [Indexed: 05/15/2023] Open
Abstract
BACKGROUND Most cases of malaria in Brazil are concentrated in the Amazon region. One of the vector control alternatives recommended by the WHO is the long-lasting insecticidal net (LLIN). This tool is used in the nine federal states of the Brazilian Legal Amazon, where LLINs are essential for reducing vector density and disease transmission as they prevent contact between the mosquito and the individual. The objective of this study was to evaluate the residuality and use of LLIN insecticides in different health regions in a city located in the Brazilian Amazon. METHODS A total of 17,027 LLINs were installed in the third, fifth and ninth health regions of the municipality of Porto Velho, Rondonia State, Brazil. The LLINs were of two types: Olyset (permethrin), for around the bed, and Interceptor (alphacypermethrin), for around hammocks. The residuality of 172 LLINs was evaluated using cone bioassays to verify the mortality rate of the mosquito Nyssorhynchus darlingi, over a period of 2 years. Structured questionnaires on the acceptance and use of LLINs were distributed to the participating population (n = 391), covering a total sample of 1147 mosquito nets. The mortality rate was evaluated both in terms of days after LLIN installation and the type of insecticide used. Statistical analyses were based on analysis of variance (ANOVA) and Chi-square and were performed using the SPSS statistical program. RESULTS For the Ny. darlingi mosquito, Interceptor-type LLINs showed residual efficacy, with mortality rates ≥ 80% during the 2-year study period, as determined by the WHO. In contrast, Olyset-type LLINs were associated with a reduction in mortality rates, with 76% and 45% mortality rates in the last two assessments, which occurred during the last 6 months of the study period. Based on the structured questionnaires, the acceptance rate, i.e. percentage of individuals accepting the permanence of the 1147 LLINs sampled, in the three health regions of Porto Velho was 93.8% (of 1076 LLINs). CONCLUSION The alphacypermethrin-impregnated LLIN was more effective than the LLIN impregnated with permethrin. The results indicate that the correct use of mosquito nets-and consequently the protection of the population-needs to be supported by health promotion actions. These initiatives are considered to be essential for the success of this vector control strategy. New studies that consider the monitoring of the placement of mosquito nets are necessary to provide effective support in the correct use of this methodology.
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Affiliation(s)
- Ana Cristina da Silva Ferreira Lima
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (IEPA), Macapá, Amapá, Brazil
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Medicina Tropical, Instituto Oswaldo Cruz FIOCRUZ, Rio de Janeiro, Brazil
| | - Allan Kardec Ribeiro Galardo
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (IEPA), Macapá, Amapá, Brazil
| | - Josiane Nogueira Müller
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (IEPA), Macapá, Amapá, Brazil.
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil.
- Programa de Pós-Graduação em Medicina Tropical, Instituto Oswaldo Cruz FIOCRUZ, Rio de Janeiro, Brazil.
| | - Ana Paula Sales de Andrade Corrêa
- Laboratório de Entomologia Médica, Instituto de Pesquisas Científicas e Tecnológicas do Estado do Amapá (IEPA), Macapá, Amapá, Brazil
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Medicina Tropical, Instituto Oswaldo Cruz FIOCRUZ, Rio de Janeiro, Brazil
| | | | | | | | | | - José Bento Pereira Lima
- Laboratório de Fisiologia e Controle de Artrópodes Vetores, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
- Programa de Pós-Graduação em Medicina Tropical, Instituto Oswaldo Cruz FIOCRUZ, Rio de Janeiro, Brazil
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Hiruy HN, Irish SR, Abdelmenan S, Wuletaw Y, Zewde A, Woyessa A, Haile M, Chibsa S, Lorenz L, Worku A, Yukich J, Berhane Y, Keating J. Durability of long-lasting insecticidal nets (LLINs) in Ethiopia. Malar J 2023; 22:109. [PMID: 36967389 PMCID: PMC10041722 DOI: 10.1186/s12936-023-04540-3] [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: 02/03/2023] [Accepted: 03/22/2023] [Indexed: 03/28/2023] Open
Abstract
BACKGROUND The functional survival time of long-lasting insecticidal nets (LLINs), which varies across different field contexts, is critical for the successful prevention of malaria transmission. However, there is limited data on LLIN durability in field settings in Ethiopia. METHODS A three-year longitudinal study was conducted to monitor attrition, physical integrity, and bio-efficacy and residual chemical concentration of LLINs in four regions in Ethiopia. World Health Organization (WHO) guidelines were used to determine sample size, measure physical integrity, and calculate attrition rates, and functional survival time. Yearly bio-efficacy testing was done on randomly selected LLINs. An excel tool developed by vector works project was used to calculate the median functional survival time of the LLINs. Predictors of functional survival were identified by fitting binary and multivariate cox proportional hazards model. RESULTS A total of 3,396 LLINs were included in the analysis. A total of 3,396 LLINs were included in the analysis. By the end of 36 months, the proportion of LLINs functionally surviving was 12.9% [95% confidence interval (CI) 10.5, 15.6], the rates of attrition due to physical damage and repurposing were 48.8% [95% confidence interval (CI) 45.0, 52.6] and 13.8% [95% confidence interval (CI) 11.6, 14.6], respectively. The estimated median functional survival time was 19 months (95%CI 17, 21). Factors associated with shorter functional survival time include being in a low malaria transmission setting [Adjusted Hazards Ratio (AHR) (95%CI) 1.77 (1.22, 2.55)], rural locations [AHR (95%CI) 1.83 (1.17, 2.84)], and in a room where cooking occurs [AHR (95%CI) 1.28 (1.05, 1.55)]. Bioassay tests revealed that 95.3% (95%CI 86.4, 98.5) of the LLINs met the WHO criteria of bio-efficacy after 24 months of distribution. CONCLUSION The LLIN survival time was shorter than the expected three years due to high attrition rates and rapid loss of physical integrity. National malaria programmes may consider, procuring more durable LLINs, educating communities on how to prevent damage of LLINs, and revising the current three-year LLIN distribution schedule to ensure sufficient protection is provided by LLINs against malaria transmission. While this paper contributes to the understanding of determinants impacting functional survival, further research is needed to understand factors for the rapid attrition rates and loss of physical integrity of LLINs in field settings.
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Affiliation(s)
- Honelgn Nahusenay Hiruy
- Department of Epidemiology and Biostatistics, Addis Continental Institute of Public Health, Addis Ababa, Ethiopia
| | - Seth R Irish
- U.S. President's Malaria Initiative, Entomology Branch, U.S. Centers for Disease Control and Prevention (CDC), Atlanta, GA, USA
| | - Semira Abdelmenan
- Department of Epidemiology and Biostatistics, Addis Continental Institute of Public Health, Addis Ababa, Ethiopia.
| | - Yonas Wuletaw
- Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Ayele Zewde
- Department of Global Health and Policy, Addis Continental Institute of Public Health, Addis Ababa, Ethiopia
| | - Adugna Woyessa
- Ethiopian Public Health Institute, Addis Ababa, Ethiopia
| | - Mebrahtom Haile
- Ethiopia Federal Ministry of Health, National Malaria Elimination Program, Addis Ababa, Ethiopia
| | - Sheleme Chibsa
- U.S. President's Malaria Initiative, USA Agency for International Development, Addis Ababa, Ethiopia
| | - Lena Lorenz
- U.S. President's Malaria Initiative, USA Agency for International Development, Addis Ababa, Ethiopia
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
- Ifakara Health Institute, Dar-Es-Salaam, Tanzania
- College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, Scotland
| | - Alemayehu Worku
- Department of Epidemiology and Biostatistics, Addis Continental Institute of Public Health, Addis Ababa, Ethiopia
| | - Josh Yukich
- Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Yemane Berhane
- Department of Epidemiology and Biostatistics, Addis Continental Institute of Public Health, Addis Ababa, Ethiopia
| | - Joseph Keating
- Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
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9
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Meza FC, Muyaga LL, Limwagu AJ, Lwetoijera DW. The ability of Anopheles funestus and A. arabiensis to penetrate LLINs and its effect on their mortality. Wellcome Open Res 2023; 7:265. [PMID: 36974127 PMCID: PMC10039320 DOI: 10.12688/wellcomeopenres.18242.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/02/2023] [Indexed: 02/09/2023] Open
Abstract
Background: Variation in mosquito body size and the ability to penetrate long-lasting insecticide-treated nets (LLINs) remains unknown. This study evaluated the ability of Anopheles funestus and A. arabiensis to penetrate commercially available treated and untreated bednets and how this behaviour affects mosquito mortality. Methods: Three types of LLINs; DawaPlus 2.0, PermaNet 2.0, Olyset 2.0, and untreated (Safi Net) were tested inside a semi-field system. One hundred 3–5-day-old female A. funestus and A. arabiensis were released in a chamber with a sleeping adult volunteer under a treated or untreated bednet. Mosquitoes that penetrated inside the nets were collected every two hours using a mouth aspirator. Live mosquitoes were put in paper cups, fed on glucose ad libitum and their mortality rate was monitored for 48 h. Results: The ability of A. funestus to penetrate treated and untreated bednets was significantly higher than for A. arabiensis for all three LLIN net types (P<0.001). For both species the penetration rate was higher for untreated bednets than treated ones except for the Olyset net. Regardless of the assessed mosquito species, all the mosquitoes that penetrated the net, successfully blood-fed on the sleeping volunteer. Compared to A. arabiensis, significant mortality was recorded for A. funestus that were caught inside Olyset nets within 48 hrs of monitoring (P<0.001). Conclusions: These findings demonstrate the ability of A. funestus and A. arabiensis mosquitoes to penetrate the human-occupied treated and untreated bednets. Despite this ability, mosquitoes that penetrated the bednet succumbed to death within two days.
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Affiliation(s)
- Felician Clement Meza
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Alex Julius Limwagu
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Dickson Wilson Lwetoijera
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
- Life Science and Bioengineering, Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
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10
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Meza FC, Muyaga LL, Limwagu AJ, Lwetoijera DW. The ability of Anopheles funestus and A. arabiensis to penetrate LLINs and its effect on their mortality. Wellcome Open Res 2022; 7:265. [PMID: 36974127 PMCID: PMC10039320 DOI: 10.12688/wellcomeopenres.18242.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2022] [Indexed: 11/20/2022] Open
Abstract
Background: Variation in mosquito body size and the ability to penetrate long-lasting insecticide-treated nets (LLINs) remains unknown. This study evaluated the ability of Anopheles funestus and A. arabiensis to penetrate commercially available treated and untreated bednets and how this behaviour affects mosquito mortality. Methods: Three types of LLINs; DawaPlus 2.0, PermaNet 2.0, Olyset 2.0, and untreated (Safi Net) were tested inside a semi-field system. One hundred 3–5-day-old female A. funestus and A. arabiensis were released in a chamber with a sleeping adult volunteer under a treated or untreated bednet. Mosquitoes that penetrated inside the nets were collected every two hours using a mouth aspirator. Live mosquitoes were put in paper cups, fed on glucose ad libitum and their mortality rate was monitored for 48 h. Results: The ability of A. funestus to penetrate treated and untreated bednets was significantly higher than for A. arabiensis for all three LLIN net types (P<0.001). For both species the penetration rate was higher for untreated bednets than treated ones except for the Olyset net. Of all mosquitoes that penetrated the net, regardless of the species, >90% successfully blood-fed on the sleeping volunteer. Compared to A. arabiensis, significant mortality was recorded for A. funestus that were caught inside Olyset nets within 48 hrs of monitoring (P<0.001). Conclusions: These findings demonstrate the ability of A. funestus and A. arabiensis mosquitoes to penetrate the human-occupied treated and untreated bednets. Despite this ability, mosquitoes that penetrated the bednet succumbed to death within two days.
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Affiliation(s)
- Felician Clement Meza
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Alex Julius Limwagu
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Dickson Wilson Lwetoijera
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
- Life Science and Bioengineering, Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
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11
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Diouf EH, Diouf M, Dieme C, Swamidoss I, Ngom EHM, Senghor MW, Mbaye M, Konaté A, Coulibaly Y, Tine D, Dia I, Dotson EM, Faye O, Konaté L. Evaluation of the residual efficacy and physical durability of five long-lasting insecticidal nets (LLINs) in Senegal. Malar J 2022; 21:210. [PMID: 35780153 PMCID: PMC9250169 DOI: 10.1186/s12936-022-04230-6] [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: 03/12/2022] [Accepted: 06/06/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The preventive and curative strategies of malaria are based on promoting the use of long-lasting insecticidal nets (LLINs) and treating confirmed cases with artemisinin-based combination therapy. These strategies have led to a sharp decline in the burden of malaria, which remains a significant public health problem in sub-Saharan countries. The objective of this study was to determine and compare the residual efficacy of LLINs recommended by the World Health Organization. METHODS The study was conducted in six villages in two sites in Senegal located in the Sahelo-Sudanian area of the Thiès region, 70 km from Dakar and in Mbagame, a semi-urban zone in the Senegal River Valley. A census was conducted of all sleeping places in each household to be covered by LLINs. Five brands of LLIN were distributed, and every six months, retention rates, net use, maintenance, physical integrity, insecticide chemical content, and biological efficacy were examined for each type of LLIN. RESULTS A total of 3012 LLINs were distributed in 1249 households in both sites, with an average coverage rate of 94% (95% CI 92.68-95.3). After 36 months, the average retention rate was 12.5% and this rate was respectively 20.5%, 15.1%, 10%, 7%, and 3% for Olyset Net®, Dawa Plus® 2.0, PermaNet® 2.0, NetProtect® and Life Net®, respectively. The proportion of LLINs with holes and the average number of holes per mosquito net increased significantly during each follow-up, with a large predominance of size 1 (small) holes for all types of LLINs distributed. During the three-year follow-up, bioassay mortality rates of a susceptible strain of insectary reared Anopheles coluzzii decreased in the following net types: in Dawa Plus® 2.0 (100% to 51.7%), PermaNet® 2.0 (96.6% to 83%), and Olyset Net® (96.6% to 33.3%). Mortality rates remained at 100% in Life Net® over the same time period. After 36 months, the average insecticide content per brand of LLIN decreased by 40.9% for Dawa Plus® 2.0, 31% for PermaNet® 2.0, 39.6% for NetProtect® and 51.9% for Olyset Net® and 40.1% for Life Net. CONCLUSIONS Although some net types retained sufficient insecticidal activity, based on all durability parameters measured, none of the net types survived longer than 2 years.
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Affiliation(s)
- El Hadji Diouf
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal.
| | - Mbaye Diouf
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Constentin Dieme
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Isabel Swamidoss
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | | | - Massila Wagué Senghor
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Modou Mbaye
- Laboratoire de Télédétection Appliquée, LTA/IST/FST/UCAD, Dakar, Sénégal
| | - Abdoulaye Konaté
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Youssouph Coulibaly
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Dome Tine
- Laboratoire de Télédétection Appliquée, LTA/IST/FST/UCAD, Dakar, Sénégal
| | | | - Ellen Marie Dotson
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Ousmane Faye
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
| | - Lassana Konaté
- Laboratoire d'Ecologie Vectorielle et Parasitaire, Département de Biologie Animal, Faculté Des Sciences et Techniques, Université Cheikh Anta Diop, Dakar, Sénégal
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12
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Madumla EP, Moore SJ, Moore J, Mbuba E, Mbeyela EM, Kibondo UA, C S, Mmbaga, Kobe D, Baraka J, Msellemu D, Swai JK, Mboma ZM, Odufuwa OG. "In starvation, a bone can also be meat": a mixed methods evaluation of factors associated with discarding of long-lasting insecticidal nets in Bagamoyo, Tanzania. Malar J 2022; 21:101. [PMID: 35331242 PMCID: PMC8944021 DOI: 10.1186/s12936-022-04126-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 03/17/2022] [Indexed: 11/27/2022] Open
Abstract
Background Between 2000 and 2019, more than 1.8 billion long-lasting insecticidal nets (LLINs) were distributed in Africa. While the insecticidal durability of LLINs is around 3 years, nets are commonly discarded 2 years post distribution. This study investigated the factors associated with the decision of users to discard LLINs. Methods A mixed-method sequential explanatory approach using a structured questionnaire followed by focus group discussions (FGDs) to collect information on experiences, views, reasons, how and when LLINs are discarded. Out of 6,526 households that responded to the questionnaire of LLINs durability trial, 160 households were randomly selected from the households in four villages in Bagamoyo Tanzania for FGDs but only 155 households participated in the FGDs. Five of the household representatives couldn’t participate due to unexpected circumstances. A total of sixteen FGDs each comprising of 8–10 adults were conducted; older women (40–60 years), older men (40–60 years), younger women (18–39 years), younger men (18–39 years). During the FGDs, participants visually inspected seven samples of LLINs that were “too-torn” based on Proportionate Hole Index recommended by the World Health Organization (WHO) guidelines on LLIN testing, the nets were brought to the discussion and participants had to determine if such LLINs were to be kept or discarded. The study assessed responses from the same participants that attended FGD and also responded to the structured questionnaire, 117 participants fulfilled the criteria, thus data from only 117 participants are analysed in this study. Results In FGDs, integrity of LLIN influenced the decision to discard or keep a net. Those of older age, women, and householders with lower income were more likely to classify a WHO “too-torn” net as “good”. The common methods used to discard LLINs were burning and burying. The findings were seen in the quantitative analysis. For every additional hole, the odds of discarding a WHO “too-torn” LLIN increased [OR = 1.05 (95%CI (1.04–1.07)), p < 0.001]. Younger age group [OR = 4.97 (95%CI (3.25–7.32)), p < 0.001], male-headed households [OR = 6.85 (95%CI (4.44 –10.59)), p < 0.001], and wealthy households [OR = 3.88 (95%CI (2.33–6.46)), p < 0.001] were more likely to discard LLINs. Conclusion Integrity of LLIN was the main determinant for discarding or keeping LLINs and the decision to discard the net is associated with socioeconomic status of the household, and the age and gender of respondents. WHO “too torn” nets are encouraged to be used instead of none until replacement, and disposal of nets should be based on recommendation. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04126-5.
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Affiliation(s)
- Edith P Madumla
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania. .,Nelson Mandela African Institution of Science and Technology, Tengeru, Arusha, Tanzania.
| | - Sarah J Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela African Institution of Science and Technology, Tengeru, Arusha, Tanzania.,Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland.,University of Basel, St. Petersplatz 1, CH-4002, Basel, Switzerland
| | - Jason Moore
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland
| | - Emmanuel Mbuba
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland.,University of Basel, St. Petersplatz 1, CH-4002, Basel, Switzerland
| | - Edgar M Mbeyela
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Ummi A Kibondo
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | | | - Mmbaga
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Dickson Kobe
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Jitihada Baraka
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Daniel Msellemu
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland.,University of Basel, St. Petersplatz 1, CH-4002, Basel, Switzerland
| | - Johnson K Swai
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Zawadi M Mboma
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit, Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Epidemiology and Public Health Department, Swiss Tropical and Public Health Institute, Kreuzstrasse 2, Allschwil, 4123, Basel, Switzerland.,London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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13
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Kumoji E'K, Awantang GN, Toso M, Kamara D, Bleu T, Lahai W, Sillah-Kanu M, Dosso A, Achu D, Babalola S. Ideational factors associated with net care behaviour: a multi-country analysis. Malar J 2022; 21:53. [PMID: 35177086 PMCID: PMC8851768 DOI: 10.1186/s12936-022-04053-5] [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: 08/04/2021] [Accepted: 01/17/2022] [Indexed: 11/12/2022] Open
Abstract
Background Malaria is endemic to sub-Saharan African countries. Mass and routine distribution, promotion, and use of ITNs are critical components of malaria prevention programmes. Correct and consistent use of insecticide-treated mosquito nets (ITN) is an effective strategy for malaria prevention. To extend bed-net lifespan, the World Health Organization recommends folding or tying up ITNs when they are not in use. This study analyses factors associated with net care practices in three African countries. Methods Researchers collected household data nationwide in Côte d’Ivoire, from the North and Far North regions of Cameroon, and from Port Loko and Bo districts in Sierra Leone, between 2018 and 2019. The dependent variable was respondents reporting that they fold or tie up their nets. The study adjusted for selected sociodemographic, ideational (psychosocial), and household variables using multilevel models. The analysis was limited to women of reproductive age and their male spouses/partners from households with at least one ITN: 2,940 respondents in Cameroon, 6,105 in Côte d’Ivoire, and 2,730 in Sierra Leone. Results Among respondents, 50.2% in Cameroon, 52.0% in Côte d’Ivoire and 75.6% in Sierra Leone reported folding or tying up their net when it was not in use. In all three countries, the data showed significant clustering at both household and community levels, indicating the influence of factors operating at these levels on net-care behaviour. The odds of reporting the behaviour varied significantly by geographic unit in each country. Consistent use of nets was strongly correlated with net-care behaviour. Furthermore, five ideational variables were positively associated with the outcome behaviour in all three countries: positive attitude towards net care, perceived susceptibility for malaria, response-efficacy of ITNs, perceived self-efficacy for net use, and the perception that net use was a community norm. Additional significant ideational variables included positive attitudes towards net use (Cameroon and Côte d’Ivoire), perceived severity of malaria (Côte d’Ivoire), and interpersonal communication about malaria (Côte d’Ivoire). Conclusions The study identified ideational variables associated with recommended net-care practice. Programme efforts designed to promote net-care practices and extend average lifespan of ITNs may be more effective if they emphasize positive attitudes towards net care, perceived susceptibility of malaria infection, response-efficacy of ITNs, perceived self-efficacy for net use, and promote net-care behaviour as a positive community norm. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04053-5.
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Affiliation(s)
- E 'Kuor Kumoji
- Johns Hopkins Center for Communication Programs, 111 Market Place, Suite 310, Baltimore, MD, 21202, USA.
| | - Grace N Awantang
- Johns Hopkins Center for Communication Programs, 111 Market Place, Suite 310, Baltimore, MD, 21202, USA
| | - Michael Toso
- Johns Hopkins Center for Communication Programs, 111 Market Place, Suite 310, Baltimore, MD, 21202, USA
| | - Diarra Kamara
- Johns Hopkins Center for Communication Programs, 111 Market Place, Suite 310, Baltimore, MD, 21202, USA
| | - Thérèse Bleu
- Programme National de Lutte Contre Le Paludisme, Abidjan, Côte d'Ivoire
| | - Wani Lahai
- National Malaria Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Musa Sillah-Kanu
- National Malaria Control Program, Ministry of Health and Sanitation, Freetown, Sierra Leone
| | - Abdul Dosso
- Programme National de Lutte Contre Le Paludisme, Abidjan, Côte d'Ivoire
| | - Dorothy Achu
- Programme National de Lutte Contre Le Paludisme Au Cameroun, Yaounde, Cameroon
| | - Stella Babalola
- Johns Hopkins Center for Communication Programs, 111 Market Place, Suite 310, Baltimore, MD, 21202, USA.,Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
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14
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Lukole E, Cook J, Mosha JF, Messenger LA, Rowland M, Kleinschmidt I, Charlwood JD, Mosha FW, Manjurano A, Wright A, Protopopoff N. Protective efficacy of holed and aging PBO-pyrethroid synergist-treated nets on malaria infection prevalence in north-western Tanzania. PLOS GLOBAL PUBLIC HEALTH 2022; 2:e0000453. [PMID: 36962517 PMCID: PMC10022078 DOI: 10.1371/journal.pgph.0000453] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/21/2022] [Indexed: 01/26/2023]
Abstract
Two billion pyrethroid long-lasting insecticidal nets (LLINs) have been distributed since 2004 for malaria prevention in Sub-Saharan Africa. Current malaria control strategies rely on an assumed effective 3-year lifespan for LLINs. PBO synergist LLINs are a newly recommended class of net but there is limited information on their life span and long-term protective efficacy in communities. To assess their operational survival, a cohort of 390 PBO LLINs (Olyset Plus) and 367 standard pyrethroid LLIN (Olyset net) from 396 households were followed for 36 months in Western Tanzania. To assess the association between the condition of the LLIN and malaria infection, nets from at least 480 randomly selected households were assessed during malaria prevalence cross-sectional surveys at 4, 9, 16, 21, 28, and 33 months post-distribution. Information on the presence and condition of nets, and demographic information from the household, were collected to evaluate factors influencing net durability. After 3 years less than 17% of nets distributed still remained in the households. The fabric condition was not associated with malaria infection in either type of net. The difference between the net types was highest when nets were between 1-2 years old, when PBO nets appeared to be similarly protective as nets less than a year old, whereas standard nets were considerably less protective as they aged, regardless of fabric condition. There was no statistical difference in the estimated median functional survival time between net types with 1.6 years (95% CI 1.38-1.87) for PBO LLIN and 1.9 years (95% CI 1.67-2.06) for standard LLINs. After 3 years, there was a loss of 55% of permethrin (pyrethroid) content for both nets, and 97% of PBO content was lost in PBO LLIN. These results highlight that functional survival is less than the recommended 3 years for both net types. However, even as the nets age, the PBO nets remained more protective than standard nets, regardless of their condition.
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Affiliation(s)
- Eliud Lukole
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Jackie Cook
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Jacklin F Mosha
- Department of Parasitology, National Institute for Medical Research, Mwanza Medical Research Centre, Mwanza, Tanzania
| | - Louisa A Messenger
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Mark Rowland
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Immo Kleinschmidt
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
- 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
| | - Jacques D Charlwood
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Franklin W Mosha
- 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
| | - Alexandra Wright
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Natacha Protopopoff
- MRC International Statistics and Epidemiology Group, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine, London, United Kingdom
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15
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Meza FC, Muyaga LL, Limwagu AJ, Lwetoijera DW. The ability of Anopheles funestus and A. arabiensis to penetrate LLINs and its effect on their mortality. Wellcome Open Res 2022; 7:265. [PMID: 36974127 PMCID: PMC10039320.3 DOI: 10.12688/wellcomeopenres.18242.3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/04/2023] [Indexed: 04/09/2023] Open
Abstract
Background: Variation in mosquito body size and the ability to penetrate long-lasting insecticide-treated nets (LLINs) remains unknown. This study evaluated the ability of Anopheles funestus and A. arabiensis to penetrate commercially available treated and untreated bednets and how this behaviour affects mosquito mortality. Methods: Three types of LLINs; DawaPlus 2.0, PermaNet 2.0, Olyset 2.0, and untreated (Safi Net) were tested inside a semi-field system. One hundred 3-5-day-old female A. funestus and A. arabiensis were released in a chamber with a sleeping adult volunteer under a treated or untreated bednet. Mosquitoes that penetrated inside the nets were collected every two hours using a mouth aspirator. Live mosquitoes were put in paper cups, fed on glucose ad libitum and their mortality rate was monitored for 48 h. Results: The ability of A. funestus to penetrate treated and untreated bednets was significantly higher than for A. arabiensis for all three LLIN net types ( P<0.001). For both species the penetration rate was higher for untreated bednets than treated ones except for the Olyset net. Regardless of the assessed mosquito species, all the mosquitoes that penetrated the net, successfully blood-fed on the sleeping volunteer. Compared to A. arabiensis, significant mortality was recorded for A. funestus that were caught inside Olyset nets within 48 hrs of monitoring ( P<0.001). Conclusions: These findings demonstrate the ability of A. funestus and A. arabiensis mosquitoes to penetrate the human-occupied treated and untreated bednets. Despite this ability, mosquitoes that penetrated the bednet succumbed to death within two days.
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Affiliation(s)
- Felician Clement Meza
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Letus L Muyaga
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Alex Julius Limwagu
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
| | - Dickson Wilson Lwetoijera
- Environmental Health and Ecological Sciences, Ifakara Health Institute, DAR ES SALAAM, N/A, 14112, Tanzania
- Life Science and Bioengineering, Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
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16
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Gichuki PM, Kamau L, Njagi K, Karoki S, Muigai N, Matoke-Muhia D, Bayoh N, Mathenge E, Yadav RS. Bioefficacy and durability of Olyset ® Plus, a permethrin and piperonyl butoxide-treated insecticidal net in a 3-year long trial in Kenya. Infect Dis Poverty 2021; 10:135. [PMID: 34930459 PMCID: PMC8691082 DOI: 10.1186/s40249-021-00916-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Accepted: 11/01/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticide nets (LLINs) are a core malaria intervention. LLINs should retain efficacy against mosquito vectors for a minimum of three years. Efficacy and durability of Olyset® Plus, a permethrin and piperonyl butoxide (PBO) treated LLIN, was evaluated versus permethrin treated Olyset® Net. In the absence of WHO guidelines of how to evaluate PBO nets, and considering the manufacturer's product claim, Olyset® Plus was evaluated as a pyrethroid LLIN. METHODS This was a household randomized controlled trial in a malaria endemic rice cultivation zone of Kirinyaga County, Kenya between 2014 and 2017. Cone bioassays and tunnel tests were done against Anopheles gambiae Kisumu. The chemical content, fabric integrity and LLIN survivorship were monitored. Comparisons between nets were tested for significance using the Chi-square test. Exact binomial distribution with 95% confidence intervals (95% CI) was used for percentages. The WHO efficacy criteria used were ≥ 95% knockdown and/or ≥ 80% mortality rate in cone bioassays and ≥ 80% mortality and/or ≥ 90% blood-feeding inhibition in tunnel tests. RESULTS At 36 months, Olyset® Plus lost 52% permethrin and 87% PBO content; Olyset® Net lost 24% permethrin. Over 80% of Olyset® Plus and Olyset® Net passed the WHO efficacy criteria for LLINs up to 18 and 12 months, respectively. At month 36, 91.2% Olyset® Plus and 86.4% Olyset® Net survived, while 72% and 63% developed at least one hole. The proportionate Hole Index (pHI) values representing nets in good, serviceable and torn condition were 49.6%, 27.1% and 23.2%, respectively for Olyset® Plus, and 44.9%, 32.8% and 22.2%, respectively for Olyset® Net but were not significantly different. CONCLUSIONS Olyset® Plus retained efficacy above or close to the WHO efficacy criteria for about 2 years than Olyset® Net (1-1.5 years). Both nets did not meet the 3-year WHO efficacy criteria, and showed little attrition, comparable physical durability and survivorship, with 50% of Olyset® Plus having good and serviceable condition after 3 years. Better community education on appropriate use and upkeep of LLINs is essential to ensure effectiveness of LLIN based malaria interventions.
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Affiliation(s)
- Paul M Gichuki
- Eastern & Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya. .,School of Health Sciences, Meru University of Science and Technology, Meru, Kenya.
| | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Kiambo Njagi
- Division of National Malaria Programme, Ministry of Health, Nairobi, Kenya
| | - Solomon Karoki
- Division of National Malaria Programme, Ministry of Health, Nairobi, Kenya
| | - Njoroge Muigai
- Department of Health, Kirinyaga County, Kirinyaga, Kenya
| | - Damaris Matoke-Muhia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, Nairobi, Kenya
| | - Nabie Bayoh
- Centre for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya.,Centers for Disease Control and Prevention, Kisumu, Kenya
| | - Evan Mathenge
- Eastern & Southern Africa Centre of International Parasite Control, Kenya Medical Research Institute, Nairobi, Kenya
| | - Rajpal S Yadav
- Department of Control of Neglected Tropical Diseases, World Health Organization, Geneva, Switzerland
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17
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Smith T, Denz A, Ombok M, Bayoh N, Koenker H, Chitnis N, Briet O, Yukich J, Gimnig JE. Incidence and consequences of damage to insecticide-treated mosquito nets in Kenya. Malar J 2021; 20:476. [PMID: 34930254 PMCID: PMC8686568 DOI: 10.1186/s12936-021-03978-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 11/10/2021] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Efforts to improve the impact of long-lasting insecticidal nets (LLINs) should be informed by understanding of the causes of decay in effect. Holes in LLINs have been estimated to account for 7-11% of loss in effect on vectorial capacity for Plasmodium falciparum malaria in an analysis of repeated cross-sectional surveys of LLINs in Kenya. This does not account for the effect of holes as a cause of net attrition or non-use, which cannot be measured using only cross-sectional data. There is a need for estimates of how much these indirect effects of physical damage on use and attrition contribute to decay in effectiveness of LLINs. METHODS Use, physical integrity, and survival were assessed in a cohort of 4514 LLINs followed for up to 4 years in Kenya. Flow diagrams were used to illustrate how the status of nets, in terms of categories of use, physical integrity, and attrition, changed between surveys carried out at 6-month intervals. A compartment model defined in terms of ordinary differential equations (ODEs) was used to estimate the transition rates between the categories. Effects of physical damage to LLINs on use and attrition were quantified by simulating counterfactuals in which there was no damage. RESULTS Allowing for the direct effect of holes, the effect on use, and the effect on attrition, 18% of the impact on vectorial capacity was estimated to be lost because of damage. The estimated median lifetime of the LLINs was 2.9 years, but this was extended to 5.7 years in the counterfactual without physical damage. Nets that were in use were more likely to be in a damaged state than unused nets but use made little direct difference to LLIN lifetimes. Damage was reported as the reason for attrition for almost half of attrited nets, but the model estimated that almost all attrited nets had suffered some damage before attrition. CONCLUSIONS Full quantification of the effects of damage will require measurement of the supply of new nets and of household stocks of unused nets, and also of their impacts on both net use and retention. The timing of mass distribution campaigns is less important than ensuring sufficient supply. In the Kenyan setting, nets acquired damage rapidly once use began and the damage led to rapid attrition. Increasing the robustness of nets could substantially increase their lifetime and impact but the impact of LLIN programmes on malaria transmission is ultimately limited by levels of use. Longitudinal analyses of net integrity data from different settings are needed to determine the importance of physical damage to nets as a driver of attrition and non-use, and the importance of frequent use as a cause of physical damage in different contexts.
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Affiliation(s)
- Thomas Smith
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.
- University of Basel, 4001, Basel, Switzerland.
| | - Adrian Denz
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland
- University of Basel, 4001, Basel, Switzerland
| | - Maurice Ombok
- Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - Nabie Bayoh
- Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | | | - Nakul Chitnis
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland
- University of Basel, 4001, Basel, Switzerland
| | - Olivier Briet
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland
- University of Basel, 4001, Basel, Switzerland
| | - Joshua Yukich
- Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - John E Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
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18
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Cote CM, Goel V, Muhindo R, Baguma E, Ntaro M, Shook-Sa BE, Reyes R, Staedke SG, Mulogo EM, Boyce RM. Malaria prevalence and long-lasting insecticidal net use in rural western Uganda: results of a cross-sectional survey conducted in an area of highly variable malaria transmission intensity. Malar J 2021; 20:304. [PMID: 34225756 PMCID: PMC8256478 DOI: 10.1186/s12936-021-03835-7] [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: 04/09/2021] [Accepted: 06/27/2021] [Indexed: 11/22/2022] Open
Abstract
Background Long-lasting insecticidal nets (LLINs) remain a cornerstone of malaria control, but strategies to sustain universal coverage and high rates of use are not well-defined. A more complete understanding of context-specific factors, including transmission intensity and access to health facilities, may inform sub-district distribution approaches and tailored messaging campaigns. Methods A cross-sectional survey of 2190 households was conducted in a single sub-county of western Uganda that experiences highly variable malaria transmission intensity. The survey was carried out approximately 3 years after the most recent mass distribution campaign. At each household, study staff documented reported LLIN use and source among children 2 to 10 years of age and performed a malaria rapid diagnostic test. Elevation and distance to the nearest health facility was estimated for each household. Associations between parasite prevalence and LLIN use were estimated from log binomial regression models with elevation and distance to clinic being the primary variables of interest. Results Overall, 6.8% (148 of 2170) of children age 2–10 years of age had a positive RDT result, yielding a weighted estimate of 5.8% (95% confidence interval [CI] 5.4–6.2%). There was substantial variability in the positivity rates among villages, with the highest elevation villages having lower prevalence than lowest-elevation villages (p < .001). Only 64.7% (95% CI 64.0–65.5%) of children were reported to have slept under a LLIN the previous night. Compared to those living < 1 km from a health centre, households at ≥ 2 km were less likely to report the child sleeping under a LLIN (RR 0.86, 95% CI 0.83–0.89, p < .001). Households located farther from a health centre received a higher proportion of LLINs from government distributions compared to households living closer to health centres. Conclusions LLIN use and sourcing was correlated with household elevation and estimated distance to the nearest health facility. The findings suggest that current facility-based distribution strategies are limited in their reach. More frequent mass distribution campaigns and complementary approaches are likely required to maintain universal LLIN coverage and high rates of use among children in rural Uganda. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03835-7.
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Affiliation(s)
- Claire M Cote
- Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Varun Goel
- Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.,Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rabbison Muhindo
- Department of Community Health, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Emmanuel Baguma
- Department of Community Health, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Moses Ntaro
- Department of Community Health, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Bonnie E Shook-Sa
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Raquel Reyes
- Division of Hospital Medicine, UNC School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Edgar M Mulogo
- Department of Community Health, Mbarara University of Science and Technology, Mbarara, Uganda
| | - Ross M Boyce
- Department of Community Health, Mbarara University of Science and Technology, Mbarara, Uganda. .,Institute of Global Health and Infectious Diseases, UNC School of Medicine, University of North Carolina at Chapel Hill, 130 Mason Farm Road, CB 7030, Chapel Hill, NC, 27599, USA.
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19
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Namuganga JF, Epstein A, Nankabirwa JI, Mpimbaza A, Kiggundu M, Sserwanga A, Kapisi J, Arinaitwe E, Gonahasa S, Opigo J, Ebong C, Staedke SG, Shililu J, Okia M, Rutazaana D, Maiteki-Sebuguzi C, Belay K, Kamya MR, Dorsey G, Rodriguez-Barraquer I. The impact of stopping and starting indoor residual spraying on malaria burden in Uganda. Nat Commun 2021; 12:2635. [PMID: 33976132 PMCID: PMC8113470 DOI: 10.1038/s41467-021-22896-5] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 04/01/2021] [Indexed: 12/03/2022] Open
Abstract
The scale-up of malaria control efforts has led to marked reductions in malaria burden over the past twenty years, but progress has slowed. Implementation of indoor residual spraying (IRS) of insecticide, a proven vector control intervention, has been limited and difficult to sustain partly because questions remain on its added impact over widely accepted interventions such as bed nets. Using data from 14 enhanced surveillance health facilities in Uganda, a country with high bed net coverage yet high malaria burden, we estimate the impact of starting and stopping IRS on changes in malaria incidence. We show that stopping IRS was associated with a 5-fold increase in malaria incidence within 10 months, but reinstating IRS was associated with an over 5-fold decrease within 8 months. In areas where IRS was initiated and sustained, malaria incidence dropped by 85% after year 4. IRS could play a critical role in achieving global malaria targets, particularly in areas where progress has stalled.
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Affiliation(s)
| | - Adrienne Epstein
- Department of Epidemiology and Biostatistics, University of California San Francisco, San Francisco, CA, USA.
| | - Joaniter I Nankabirwa
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University, College of Health Sciences, Kampala, Uganda
| | - Arthur Mpimbaza
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Child Health and Development Centre, Makerere University, College of Health Sciences, Kampala, Uganda
| | - Moses Kiggundu
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - James Kapisi
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | | | - Jimmy Opigo
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | - Chris Ebong
- Infectious Diseases Research Collaboration, Kampala, Uganda
| | | | - Josephat Shililu
- US President's Malaria Initiative - VectorLink Uganda Project, Kampala, Uganda
| | - Michael Okia
- US President's Malaria Initiative - VectorLink Uganda Project, Kampala, Uganda
| | - Damian Rutazaana
- National Malaria Control Division, Ministry of Health, Kampala, Uganda
| | | | - Kassahun Belay
- US President's Malaria Initiative, USAID/Uganda Senior Malaria Advisor, Kampala, Uganda
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, Kampala, Uganda
- Department of Medicine, Makerere University, College of Health Sciences, Kampala, Uganda
| | - Grant Dorsey
- Department of Medicine, University of California San Francisco, San Francisco, CA, USA
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20
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Mboma ZM, Festo C, Lorenz LM, Massue DJ, Kisinza WN, Bradley J, Moore JD, Mandike R, Akim I, Lines J, Overgaard HJ, Moore SJ. The consequences of declining population access to insecticide-treated nets (ITNs) on net use patterns and physical degradation of nets after 22 months of ownership. Malar J 2021; 20:171. [PMID: 33781261 PMCID: PMC8008556 DOI: 10.1186/s12936-021-03686-2] [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: 09/17/2020] [Accepted: 03/05/2021] [Indexed: 11/30/2022] Open
Abstract
Background As insecticide-treated nets (ITNs) wear out and are disposed, some household members are prioritized to use remaining ITNs. This study assessed how nets are allocated within households to individuals of different age categories as ITNs are lost or damaged and as new ITNs are obtained. The study also explored how ITN allocation affects ITN durability. Methods A cross-sectional household survey and ITN durability study was conducted among 2,875 households across Tanzania to determine the proportion of nets that remain protective (serviceable) 22 months after net distribution aiming for universal coverage. Allocation of study nets within houses, and re-allocation of ITNs when new universal replacement campaign (URC) nets arrived in study households in Musoma District, was also assessed. Results Some 57.0% (95% CI 53.9–60.1%) of households had sufficient ITNs for every household member, while 84.4% (95% CI 82.4–86.4%) of the population had access to an ITN within their household (assuming 1 net covers every 2 members). In households with sufficient nets, 77.5% of members slept under ITNs. In households without sufficient nets, pregnant women (54.6%), children < 5 years (45.8%) and adults (42.1%) were prioritized, with fewer school-age children 5–14 years (35.9%), youths 15–24 years (28.1%) and seniors > 65 years (32.6%) sleeping under ITNs. Crowding (\documentclass[12pt]{minimal}
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\begin{document}$$\ge$$\end{document}≥ 3 people sleeping under nets) was twice as common among people residing in houses without sufficient nets for all age groups, apart from children < 5. Nets were less likely to be serviceable if: \documentclass[12pt]{minimal}
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\begin{document}$$\ge$$\end{document}≥ 3 people slept under them (OR 0.50 (95% CI 0.40–0.63)), or if nets were used by school-age children (OR 0.72 (95% CI 0.56–0.93)), or if the net product was Olyset®. One month after the URC, only 23.6% (95% CI 16.7–30.6%) of the population had access to a URC ITN in Musoma district. Householders in Musoma district continued the use of old ITNs even with the arrival of new URC nets. Conclusion Users determined the useful life of ITNs and prioritized pregnant women and children < 5 to serviceable ITNs. When household net access declines, users adjust by crowding under remaining nets, which further reduces ITN lifespan. School-age children that commonly harbour gametocytes that mediate malaria transmission are compelled to sleep under unserviceable nets, crowd under nets or remain uncovered. However, they were accommodated by the arrival of new nets. More frequent ITN delivery through the school net programme in combination with mass distribution campaigns is essential to maximize ITN effectiveness. Supplementary Information The online version contains supplementary material available at 10.1186/s12936-021-03686-2.
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Affiliation(s)
- Zawadi M Mboma
- Ifakara Health Institute, Dar es Salaam, Tanzania. .,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.
| | | | - Lena M Lorenz
- Ifakara Health Institute, Dar es Salaam, Tanzania.,Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK.,College of Medicine and Veterinary Medicine, University of Edinburgh, Queen's Medical Research Institute, 47 Little France Crescent, Edinburgh, EH16 4TJ, UK
| | - Dennis J Massue
- Vector Control Product Testing Unit, Ifakara Health Institute, Ifakara, Tanzania.,Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland.,University of Dar Es Salaam, Mbeya College of Health and Allied Sciences, Box 608, Mbeya, Tanzania
| | - William N Kisinza
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanga, Tanzania
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jason D Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, Ifakara, Tanzania.,Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
| | - Renata Mandike
- Ministry of Health and Social Welfare, National Malaria Control Programme, Dar-es-Salaam, Tanzania
| | - Ikupa Akim
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland
| | - Jo Lines
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, P.O. Box 5003, 1432, Ås, Norway.,Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Sarah J Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, Ifakara, Tanzania.,Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Soccinstrase 57, 4002, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland
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21
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Villalta EL, Soto Bravo AM, Vizcaino L, Dzuris N, Delgado M, Green M, Smith SC, Lenhart A, Macedo de Oliveira A. Evaluation of the durability and use of long-lasting insecticidal nets in Nicaragua. Malar J 2021; 20:106. [PMID: 33608024 PMCID: PMC7893764 DOI: 10.1186/s12936-021-03604-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 01/22/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Vector control for malaria prevention relies most often on the use of insecticide-treated bed net (ITNs) and indoor residual spraying. Little is known about the longevity of long-lasting insecticidal nets (LLINs) in the Americas. The physical integrity and insecticide retention of LLINs over time were monitored after a bed net distribution campaign to assess community practices around LLIN care and use in Waspam, northeastern Nicaragua. METHODS At least 30 nets were collected at 6, 12, 24, and 36 months post distribution. Physical integrity was measured by counting holes and classifying nets into categories (good, damaged, and too torn) depending on a proportionate hole index (pHI). Insecticide bioefficacy was assessed using cone bioassays, and insecticide content measured using a cyanopyrethroid field test (CFT). RESULTS At 6 months, 87.3 % of LLINs were in good physical condition, while by 36 months this decreased to 20.6 %, with 38.2 % considered 'too torn.' The median pHI increased from 7 at the 6-month time point to 480.5 by 36 months. After 36 months of use, median mortality in cone bioassays was 2 % (range: 0-6 %) compared to 16 % (range: 2-70 %) at 6 months. There was a decrease in the level of deltamethrin detected on the surface of the LLINs with 100 % of tested LLINs tested at 12 months and 24 months crossing the threshold for being considered a failed net by CFT. CONCLUSIONS This first comprehensive analysis of LLIN durability in Central America revealed rapid loss of chemical bioefficacy and progressive physical damage over a 36-month period. Use of these findings to guide future LLIN interventions in malaria elimination settings in Nicaragua, and potentially elsewhere in the Americas, could help optimize the successful implementation of vector control strategies.
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Affiliation(s)
| | | | - Lucrecia Vizcaino
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA
| | - Nicole Dzuris
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA
| | - Marco Delgado
- Entomología Médica, Ministerio de Salud, Managua, Nicaragua
| | - Michael Green
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA
| | - Stephen C Smith
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA
| | - Audrey Lenhart
- Entomology Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA
| | - Alexandre Macedo de Oliveira
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, USA.
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22
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Wheldrake A, Guillemois E, Arouni H, Chetty V, Russell SJ. Textile testing to assess the resistance to damage of long-lasting insecticidal nets for malaria control and prevention. Malar J 2021; 20:47. [PMID: 33468152 PMCID: PMC7816374 DOI: 10.1186/s12936-020-03571-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/24/2020] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND LLINs are susceptible to forming holes within a short time in use, compromising their ability to provide long-term physical protection against insect-borne vectors of disease. Mechanical damage is known to be responsible for the majority of holes, with most being the result of snagging, tearing, hole enlargement, abrasion and seam failure, which can readily occur during normal household use. To enable an assessment of the ability of LLINs to resist such damage prior to distribution, a new suite of testing methods was developed to reflect the main damage mechanisms encountered during normal use of LLINs. METHODS Four existing BS EN and ISO standards used by the textile industry were adapted to determine the ability of LLINs to resist the most common mechanisms of real-world damage experienced in the field. The new suite comprised tests for snag strength (BS 15,598:2008), bursting strength (ISO 13938-2:1999), hole enlargement resistance (BS 3423-38:1998), abrasion resistance (ISO 12947-1:1998) and new guidance around the seam construction of LLINs. Fourteen different LLINs were tested using the new suite of tests to evaluate their resistance to damage. RESULTS The resistance to mechanical damage of LLINs is not the same, even when the bursting strength values are comparable. Differences in performance between LLINs are directly related to the fabric design specifications, including the knitted structure and constituent yarns. The differences in performance do not primarily relate to what polymer type the LLIN is made from. LLINs made with a Marquisette knitted structure produced the highest snag strength and lowest hole enlargement values. By contrast, LLINs made with a traverse knitted structure exhibited low snag strength values when compared at the same mesh count. CONCLUSIONS Prequalification of LLINs should consider not only insecticidal performance, but also inherent resistance to mechanical damage. This is critical to ensuring LLINs are fit for purpose prior to distribution, and are capable of remaining in good physical condition for longer. The new suite of test methods enables the performance of LLINs to be assessed and specified in advance of distribution and can be used to establish minimum performance standards. Implementation of these testing methods is therefore recommended.
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Affiliation(s)
- Amy Wheldrake
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Estelle Guillemois
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Hamidreza Arouni
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Vera Chetty
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Stephen J Russell
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK.
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Wheldrake A, Guillemois E, Arouni H, Chetty V, Russell SJ. The causes of holes and loss of physical integrity in long-lasting insecticidal nets. Malar J 2021; 20:45. [PMID: 33468114 PMCID: PMC7816425 DOI: 10.1186/s12936-020-03567-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 12/22/2020] [Indexed: 11/17/2022] Open
Abstract
Background Long-lasting insecticidal nets (LLINs) are expected to last for at least 3 years, but whilst this may be achieved from an insecticidal perspective, physical protection is frequently compromised much earlier because of the rapid accumulation of holes during use. To understand why LLINs are so susceptible to loss of physical integrity, thousands of hole damage sites in LLINs retrieved from the field in Africa and Asia were forensically studied to identify the persistent underlying causes. Methods A total of 525 LLINs consisting of six different brands from five different countries across Africa and Asia were collected from the field after 1 to 3 years in use. More than 42,000 individual sites of hole damage were analysed based on the morphology and size of each individual hole, aided by optical microscopy (OM) and scanning electron microscopy (SEM). The fracture morphology enabled positive identification of the underlying mechanisms of the damage. Results Across all LLINs and geographical settings, mechanical damage is the primary cause of holes and loss of physical integrity in LLINs (63.14% by frequency and 81.52% by area). Snagging is the single most frequent mechanical damage mechanism, whilst the largest sized holes in LLINs result from seam failure and tearing. Abrasion and hole enlargement are also responsible for a progressive loss in the physical integrity of nets. Collectively, these five modes of mechanical damage can be expected to result from normal use of LLINs by households. Evidence of deliberate cutting, burn holes and rodent damage was observed to a lesser degree, which LLINs are not designed to withstand. Conclusions Loss of physical integrity in LLINs is an inevitable consequence of using a vector control product that has an inherently low resistance to mechanical damage during normal use. To improve performance, new specifications based on laboratory textile testing is needed, to assess the resistance of LLIN products to the primary causes of mechanical damage when in use, which are snagging, tearing, abrasion and hole enlargement. Seam construction also needs to meet a revised minimum standard to reduce the risk of a rapid loss of physical integrity during use.
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Affiliation(s)
- Amy Wheldrake
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Estelle Guillemois
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Hamidreza Arouni
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Vera Chetty
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK
| | - Stephen J Russell
- Nonwovens Innovation & Research Institute Ltd, 169 Meanwood Road, Leeds, LS7 1SR, West Yorkshire, UK.
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24
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Lorenz LM, Bradley J, Yukich J, Massue DJ, Mageni Mboma Z, Pigeon O, Moore J, Kilian A, Lines J, Kisinza W, Overgaard HJ, Moore SJ. Comparative functional survival and equivalent annual cost of 3 long-lasting insecticidal net (LLIN) products in Tanzania: A randomised trial with 3-year follow up. PLoS Med 2020; 17:e1003248. [PMID: 32946451 PMCID: PMC7500675 DOI: 10.1371/journal.pmed.1003248] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 08/17/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Two billion long-lasting insecticidal nets (LLINs) have been procured for malaria control. A functional LLIN is one that is present, is in good physical condition, and remains insecticidal, thereby providing protection against vector-borne diseases through preventing bites and killing disease vectors. The World Health Organization (WHO) prequalifies LLINs that remain adequately insecticidal 3 years after deployment. Therefore, institutional buyers often assume that prequalified LLINs are functionally identical with a 3-year lifespan. We measured the lifespans of 3 LLIN products, and calculated their cost per year of functional life, to demonstrate the economic and public health importance of procuring the most cost-effective LLIN product based on its lifespan. METHODS AND FINDINGS A randomised double-blinded trial of 3 pyrethroid LLIN products (10,571 nets in total) was conducted at 3 follow-up points: 10 months (August-October 2014), 22 months (August-October 2015), and 36 months (October-December 2016) among 3,393 households in Tanzania using WHO-recommended methods. Primary outcome was LLIN functional survival (LLIN present and in serviceable condition). Secondary outcomes were (1) bioefficacy and chemical content (residual insecticidal activity) and (2) protective efficacy for volunteers sleeping under the LLINs (bite reduction and mosquitoes killed). Median LLIN functional survival was significantly different between the 3 net products (p = 0.001): 2.0 years (95% CI 1.7-2.3) for Olyset, 2.5 years (95% CI 2.2-2.8) for PermaNet 2.0 (hazard ratio [HR] 0.73 [95% CI 0.64-0.85], p = 0.001), and 2.6 years (95% CI 2.3-2.8) for NetProtect (HR = 0.70 [95% CI 0.62-0.77], p < 0.001). Functional survival was affected by accumulation of holes, leading to users discarding nets. Protective efficacy also significantly differed between products as they aged. Equivalent annual cost varied between US$1.2 (95% CI $1.1-$1.4) and US$1.5 (95% CI $1.3-$1.7), assuming that each net was priced identically at US$3. The 2 longer-lived nets (PermaNet and NetProtect) were 20% cheaper than the shorter-lived product (Olyset). The trial was limited to only the most widely sold LLINs in Tanzania. Functional survival varies by country, so the single country setting is a limitation. CONCLUSIONS These results suggest that LLIN functional survival is less than 3 years and differs substantially between products, and these differences strongly influence LLIN value for money. LLIN tendering processes should consider local expectations of cost per year of functional life and not unit price. As new LLIN products come on the market, especially those with new insecticides, it will be imperative to monitor their comparative durability to ensure that the most cost-effective products are procured for malaria control.
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Affiliation(s)
- Lena M. Lorenz
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene &Tropical Medicine, London, United Kingdom
- Queen’s Medical Research Institute, College of Medicine and Veterinary Medicine, University of Edinburgh, Edinburgh, United Kingdom
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene & Tropical Medicine, London, United Kingdom
| | - Joshua Yukich
- Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, Louisiana, United States of America
| | - Dennis J. Massue
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
- Vector Control Product Testing Unit, Ifakara Health Institute, Bagamoyo, Tanzania
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Zawadi Mageni Mboma
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene &Tropical Medicine, London, United Kingdom
- Ifakara Health Institute, Dar es Salaam, Tanzania
| | - Olivier Pigeon
- Plant Protection Products and Biocides Physico-chemistry and Residues Unit, Agriculture and Natural Environment Department, Walloon Agricultural Research Centre, Gembloux, Belgium
| | - Jason Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, Bagamoyo, Tanzania
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Basel, Switzerland
| | | | - Jo Lines
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene &Tropical Medicine, London, United Kingdom
| | - William Kisinza
- National Institute for Medical Research, Amani Research Centre, Muheza, Tanzania
| | - Hans J. Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
- Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand
| | - Sarah J. Moore
- Vector Control Product Testing Unit, Ifakara Health Institute, Bagamoyo, Tanzania
- Epidemiology and Public Health Department, Swiss Institute of Tropical and Public Health, Basel, Switzerland
- University of Basel, Basel, Switzerland
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Briet O, Koenker H, Norris L, Wiegand R, Vanden Eng J, Thackeray A, Williamson J, Gimnig JE, Fortes F, Akogbeto M, Yadouleton AW, Ombok M, Bayoh MN, Mzilahowa T, Abílio AP, Mabunda S, Cuamba N, Diouf E, Konaté L, Hamainza B, Katebe-Sakala C, Ponce de León G, Asamoa K, Wolkon A, Smith SC, Swamidoss I, Green M, Gueye S, Mihigo J, Morgan J, Dotson E, Craig AS, Tan KR, Wirtz RA, Smith T. Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity. Malar J 2020; 19:310. [PMID: 32859210 PMCID: PMC7456088 DOI: 10.1186/s12936-020-03383-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Accepted: 08/19/2020] [Indexed: 11/25/2022] Open
Abstract
Background Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. Methods Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission—in terms of vectorial capacity (VC)—provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. Results There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. Conclusions There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.
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Affiliation(s)
- Olivier Briet
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.,University of Basel, 4001, Basel, Switzerland
| | - Hannah Koenker
- PMI VectorWorks, JHU Center for Communication Programs, Baltimore, MD, USA.,Tropical Health LLP, Baltimore, MD, USA
| | - Laura Norris
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Washington, DC, USA.,Bill & Melinda Gates Foundation, Seattle, WA, USA
| | - Ryan Wiegand
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Jodi Vanden Eng
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | | | - John Williamson
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - John E Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Filomeno Fortes
- National Malaria Control Program (NMCP), Ministry of Health, Luanda, Angola.,Institute of Hygiene and Tropical Medicine, NOVA University Lisbon, Lisbon, Portugal
| | - Martin Akogbeto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin
| | - Anges W Yadouleton
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Programme National de Lutte contre le Paludisme (PNLP), Ministry of Health, Cotonou, Bénin
| | - Maurice Ombok
- Kenya Medical Research Institute (KEMRI), Kisumu, Kenya
| | - M Nabie Bayoh
- Kenya Medical Research Institute (KEMRI), Kisumu, Kenya.,PMI VectorLink Project, Abt Associates, Lusaka, Zambia
| | - Themba Mzilahowa
- College of Medicine, Malaria Alert Centre, P/Bag 360, Blantyre 3, Malawi
| | - Ana Paula Abílio
- Instituto Nacional de Saúde (INS), Ministério da Saúde, Maputo, Mozambique
| | - Samuel Mabunda
- Instituto Nacional de Saúde (INS), Ministério da Saúde, Maputo, Mozambique.,National Malaria Control Programme (NMCP), Ministry of Health, Maputo, Mozambique
| | - Nelson Cuamba
- Instituto Nacional de Saúde (INS), Ministério da Saúde, Maputo, Mozambique.,National Malaria Control Programme (NMCP), Ministry of Health, Maputo, Mozambique
| | - Elhadji Diouf
- Faculté des Sciences et Techniques (FST), Université Cheikh Anta Diop (UCAD), Dakar, Senegal
| | - Lassana Konaté
- Faculté des Sciences et Techniques (FST), Université Cheikh Anta Diop (UCAD), Dakar, Senegal
| | | | | | - Gabriel Ponce de León
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Kwame Asamoa
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Adam Wolkon
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Stephen C Smith
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Isabel Swamidoss
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Mike Green
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Salam Gueye
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Jules Mihigo
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Juliette Morgan
- U.S. President's Malaria Initiative, Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Ellen Dotson
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Allen S Craig
- U.S. President's Malaria Initiative, Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Kathrine R Tan
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Robert A Wirtz
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA, USA
| | - Tom Smith
- Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland. .,University of Basel, 4001, Basel, Switzerland.
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26
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Okumu F. The fabric of life: what if mosquito nets were durable and widely available but insecticide-free? Malar J 2020; 19:260. [PMID: 32690016 PMCID: PMC7370456 DOI: 10.1186/s12936-020-03321-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 07/04/2020] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Bed nets are the commonest malaria prevention tool and arguably the most cost-effective. Their efficacy is because they prevent mosquito bites (a function of physical durability and integrity), and kill mosquitoes (a function of chemical content and mosquito susceptibility). This essay follows the story of bed nets, insecticides and malaria control, and asks whether the nets must always have insecticides. METHODS Key attributes of untreated or pyrethroid-treated nets are examined alongside observations of their entomological and epidemiological impacts. Arguments for and against adding insecticides to nets are analysed in contexts of pyrethroid resistance, personal-versus-communal protection, outdoor-biting, need for local production and global health policies. FINDINGS Widespread resistance in African malaria vectors has greatly weakened the historical mass mosquitocidal effects of insecticide-treated nets (ITNs), which previously contributed communal benefits to users and non-users. Yet ITNs still achieve substantial epidemiological impact, suggesting that physical integrity, consistent use and population-level coverage are increasingly more important than mosquitocidal properties. Pyrethroid-treatment remains desirable where vectors are sufficiently susceptible, but is no longer universally necessary and should be re-examined alongside other attributes, e.g. durability, coverage, acceptability and access. New ITNs with multiple actives or synergists could provide temporary relief in some settings, but their performance, higher costs, and drawn-out innovation timelines do not justify singular emphasis on insecticides. Similarly, sub-lethal insecticides may remain marginally-impactful by reducing survival of older mosquitoes and disrupting parasite development inside the mosquitoes, but such effects vanish under strong resistance. CONCLUSIONS The public health value of nets is increasingly driven by bite prevention, and decreasingly by lethality to mosquitoes. For context-appropriate solutions, it is necessary to acknowledge and evaluate the potential and cost-effectiveness of durable untreated nets across different settings. Though ~ 90% of malaria burden occurs in Africa, most World Health Organization-prequalified nets are manufactured outside Africa, since many local manufacturers lack capacity to produce the recommended insecticidal nets at competitive scale and pricing. By relaxing conditions for insecticides on nets, it is conceivable that non-insecticidal but durable, and possibly bio-degradable nets, could be readily manufactured locally. This essay aims not to discredit ITNs, but to illustrate how singular focus on insecticides can hinder innovation and sustainability.
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Affiliation(s)
- Fredros Okumu
- Environmental Health & 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 & Comparative Medicine, University of Glasgow, Glasgow, UK.
- School of Life Science and Bioengineering, Nelson Mandela African Institution of Science & Technology, Arusha, Tanzania.
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27
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Haji KA, Khatib BO, Obi E, Dimoso K, Koenker H, Babalola S, Greer G, Serbantez N, Abbas F, Ali A, Blaufuss S, Olapeju B, Kilian A. Monitoring the durability of the long-lasting insecticidal nets Olyset ® and PermaNet ® 2.0 in similar use environments in Zanzibar. Malar J 2020; 19:187. [PMID: 32448313 PMCID: PMC7247136 DOI: 10.1186/s12936-020-03258-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 05/15/2020] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Malaria transmission in Zanzibar has dramatically reduced in recent years but vector control interventions such as long-lasting insecticidal nets (LLIN) must continue to reach malaria elimination. To achieve this, the Zanzibar Malaria Elimination Programme needs actionable evidence of the durability of the LLIN brands distributed. This study compared physical and insecticidal durability of two LLIN brands: Olyset® and PermaNet© 2.0 in two similar districts on the islands of Unguja and Pemba. METHODS This was a prospective cohort study of representative samples of households from two districts, recruited at baseline 4 months after the mass campaign. All campaign nets in these households were labelled and followed up over a period of 33 months. Primary outcome was the "proportion of nets surviving in serviceable condition" based on attrition and integrity measures and the median survival in years. The outcome for insecticidal durability was determined by bio-assay from sub-samples of campaign nets. RESULTS A total of 834 campaign nets (121% of target) from 299 households were included in the study. Definite outcomes could be determined for 86% of the cohort nets in Unguja (PermaNet® 2.0) and 89% in Pemba (Olyset®). After 33 months, physical survival in serviceable condition was 55% in Unguja and 51% in Pemba. Estimated median survival was lower in Pemba at all time points with 2.3-2.7 years compared to 3.1-3.3 yeas in Unguja. Multivariable Cox proportionate hazard models confirmed the difference between brands (p < 0.0001) and identified household net-care attitude (p = 0.007) and folding of hanging nets during the day (p < 0.0001) as significant determinants, in addition to exclusive use of nets by adults (p = 0.03) and use only over a finished bedframe (p = 0.01). Optimal insecticidal effectiveness was 80% or higher for both brands at all time points when both cone bio-assays and tunnel tests were applied. CONCLUSIONS After 3 years of follow-up, Olyset® LLIN showed significantly lower physical survival compared to PermaNet® 2.0 LLIN even after adjusting for other variables of net-use environment and net handling. This suggests that the differences were driven by the textile characteristics of the LLIN brands.
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Affiliation(s)
- Khamis Ameir Haji
- Zanzibar Malaria Elimination Programme, Stone Town, Zanzibar, Tanzania
| | | | - Emmanuel Obi
- PMI VectorWorks Project, Tropical Health LLP, Abuja, Nigeria
| | - Kanuth Dimoso
- PMI VectorWorks Project, JHU Center for Communication Programs, Dar es Salaam, Tanzania
| | - Hannah Koenker
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Stella Babalola
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - George Greer
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Naomi Serbantez
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Faiza Abbas
- Zanzibar Malaria Elimination Programme, Stone Town, Zanzibar, Tanzania
| | - Abdullah Ali
- Zanzibar Malaria Elimination Programme, Stone Town, Zanzibar, Tanzania
| | - Sean Blaufuss
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Bolanle Olapeju
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Albert Kilian
- PMI VectorWorks Project, Tropical Health LLP, Montagut, Spain.
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28
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Killeen GF. Control of malaria vectors and management of insecticide resistance through universal coverage with next-generation insecticide-treated nets. Lancet 2020; 395:1394-1400. [PMID: 32304648 DOI: 10.1016/s0140-6736(20)30745-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 03/15/2020] [Accepted: 03/17/2020] [Indexed: 12/23/2022]
Affiliation(s)
- Gerry F Killeen
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania; School of Biological, Earth and Environmental Sciences, University College Cork, Cork, Ireland.
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29
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Yukich J, Stuck L, Scates S, Wisniewski J, Chacky F, Festo C, Kabulika G, Dimoso K, Mandike R, Greer G, Serbantez N, Elisaria E, Nyoni W, Dadi D, Akim I, Lengeler C, Brown N, Koenker H. Sustaining LLIN coverage with continuous distribution: the school net programme in Tanzania. Malar J 2020; 19:158. [PMID: 32303240 PMCID: PMC7164342 DOI: 10.1186/s12936-020-03222-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 04/03/2020] [Indexed: 12/18/2022] Open
Abstract
Most malaria-endemic countries have struggled in the past decade to establish effective national-scale continuous distribution mechanisms for long-lasting insecticidal nets (LLINs). Since the implementation of the Tanzania National Voucher Scheme in 2004 and mass-distribution campaigns in 2009–2011 and 2015–2016, Tanzania has been committed to finding new and innovative ways of achieving and maintaining universal bed net coverage. Planning for the School Net Programme (SNP) began in 2011 and in 2013, the country piloted a SNP in three regions. Nets were distributed annually to children attending schools in selected primary and secondary grades. Intra-family re-distribution was assumed, and hence the family as a whole, rather than just the children themselves, were the targeted beneficiaries. The programme has since expanded to 14 regions and has seen six rounds of annual distribution. In its fifth year, 3 million nets were distributed at a cost of USD 3.64 per net and USD 0.60 per person-year of protection (including the net). ITN access and use were maintained at a high level (~ 50–75%) over the first 4 years of distribution within selected evaluation areas, even in the absence of a mass distribution event. Net distribution through primary schools has proven to be a feasible and effective strategy for maintaining consistently high coverage in Tanzania.
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Affiliation(s)
- Joshua Yukich
- PMI VectorWorks, Center for Applied Malaria Research and Evaluation Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA.
| | - Logan Stuck
- PMI VectorWorks, Center for Applied Malaria Research and Evaluation Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Sara Scates
- PMI VectorWorks, Center for Applied Malaria Research and Evaluation Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Janna Wisniewski
- Department of Health Policy and Management, Tulane University of School of Public Health and Tropical Medicine, New Orleans, LA, USA
| | - Frank Chacky
- National Malaria Control Program, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | | | - George Kabulika
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Dar es Salaam, Tanzania
| | - Kanuth Dimoso
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Dar es Salaam, Tanzania
| | - Renata Mandike
- National Malaria Control Program, Ministry of Health, Community Development, Gender, Elderly and Children, Dodoma, Tanzania
| | - George Greer
- U. S. President's Malaria Initiative, United States Agency for International Development, Dar es Salaam, Tanzania
| | - Naomi Serbantez
- U. S. President's Malaria Initiative, United States Agency for International Development, Dar es Salaam, Tanzania
| | | | - Waziri Nyoni
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Dar es Salaam, Tanzania
| | - David Dadi
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Dar es Salaam, Tanzania
| | - Ikupa Akim
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Christian Lengeler
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Nick Brown
- A to Z Textile Mills Ltd, Arusha, Tanzania.,Nicholas Brown Consulting Ltd., Cardiff, Wales, UK
| | - Hannah Koenker
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
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30
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Obi E, Okoh F, Blaufuss S, Olapeju B, Akilah J, Okoko OO, Okechukwu A, Maire M, Popoola K, Yahaya MA, Uneke CJ, Awolola S, Pigeon O, Babalola S, Koenker H, Kilian A. Monitoring the physical and insecticidal durability of the long-lasting insecticidal net DawaPlus ® 2.0 in three States in Nigeria. Malar J 2020; 19:124. [PMID: 32228592 PMCID: PMC7106771 DOI: 10.1186/s12936-020-03194-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Accepted: 03/20/2020] [Indexed: 11/23/2022] Open
Abstract
Background Following guidance from the US President’s Malaria Initiative, durability monitoring of DawaPlus® 2.0 brand of long-lasting insecticidal net (LLIN) distributed during the 2015/16 mass campaign was set up in three ecologically different states: Zamfara, Ebonyi and Oyo. Methods This was a prospective cohort study of representative samples of households from each location, recruited at baseline, 1 to 6 months after the mass campaign. All campaign nets in the households were labelled and followed up over a period of 36 months in Zamfara and Ebonyi and 24 months in Oyo. Primary outcome was the “proportion of nets surviving in serviceable condition” based on attrition and integrity measures and the median survival in years. The outcome for insecticidal durability was determined by bio-assay from sub-samples of campaign nets. Results A total of 439 households (98% of target) and 1096 campaign nets (106%) were included in the study. Definite outcomes could be determined for 92% of the cohort nets in Zamfara, 88% in Ebonyi and 75% in Oyo. All-cause attrition was highest in Oyo with 47% no longer present after 24 months, 53% in Ebonyi and 28% in Zamfara after 36 months. Overall only 1% of all campaign nets were used for other purposes. Estimated survival in serviceable condition of the campaign nets was 80% in Zamfara, 55% in Ebonyi (36 months follow-up) and 75% in Oyo (24 months follow-up) corresponding to median survival of 5.3, 3.3, 3.2 years, respectively. Factors associated with better survival were exposure to social messaging combined with a positive net-care attitude and only adult users. Failing to fold the net when hanging and having children under 5 years of age in the household negatively impacted net survival. Insecticidal effectiveness testing at final survey showed knock-down rates of 50–69%, but 24-h mortality above 95% resulting in 100% optimal performance in Ebonyi and Oyo and 97% in Zamfara. Conclusions Results confirm the strong influence of net-use environment and behavioural factors in the physical survival of the same LLIN brand, which can increase the time until 50% of nets are no longer serviceable by up to 2 years.
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Affiliation(s)
- Emmanuel Obi
- PMI VectorWorks Project, Tropical Health LLP, Abuja, Nigeria
| | - Festus Okoh
- National Malaria Elimination Programme, Abuja, Nigeria
| | - Sean Blaufuss
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Bolanle Olapeju
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Joel Akilah
- National Malaria Elimination Programme, Abuja, Nigeria
| | | | - Abidemi Okechukwu
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Abuja, Nigeria
| | - Mark Maire
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Abuja, Nigeria
| | | | | | - Chigozie Jesse Uneke
- Dept. of Medical Microbiology/Parasitology, Ebonyi State University, Abakaliki, Nigeria
| | | | | | - Stella Babalola
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Hannah Koenker
- PMI VectorWorks Project, JHU Center for Communication Programs, Baltimore, MD, USA
| | - Albert Kilian
- PMI VectorWorks Project, Tropical Health LLP, Montagut, Spain.
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31
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Toé KH, Mechan F, Tangena JAA, Morris M, Solino J, Tchicaya EFS, Traoré A, Ismail H, Maas J, Lissenden N, Pinder M, Lindsay SW, Tiono AB, Ranson H, Sagnon N. Assessing the impact of the addition of pyriproxyfen on the durability of permethrin-treated bed nets in Burkina Faso: a compound-randomized controlled trial. Malar J 2019; 18:383. [PMID: 31791332 PMCID: PMC6889366 DOI: 10.1186/s12936-019-3018-1] [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: 09/11/2019] [Accepted: 11/20/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) treated with pyrethroids are the foundation of malaria control in sub-Saharan Africa. Rising pyrethroid resistance in vectors, however, has driven the development of alternative net formulations. Here the durability of polyethylene nets with a novel combination of a pyrethroid, permethrin, and the insect juvenile hormone mimic, pyriproxyfen (PPF), compared to a standard permethrin LLIN, was assessed in rural Burkina Faso. METHODS A compound-randomized controlled trial was completed in two villages. In one village 326 of the PPF-permethrin nets (Olyset Duo) and 327 standard LLINs (Olyset) were distributed to assess bioefficacy. In a second village, 170 PPF-permethrin nets and 376 LLINs were distributed to assess survivorship. Nets were followed at 6-monthly intervals for 3 years. Bioefficacy was assessed by exposing permethrin-susceptible and resistant Anopheles gambiae sensu lato mosquito strains to standard World Health Organization (WHO) cone and tunnel tests with impacts on fertility measured in the resistant strain. Insecticide content was measured using high-performance liquid chromatography. LLIN survivorship was recorded with a questionnaire and assessed by comparing the physical integrity using the proportionate hole index (pHI). RESULTS The PPF-permethrin net met WHO bioefficacy criteria (≥ 80% mortality or ≥ 95% knockdown) for the first 18 months, compared to 6 months for the standard LLIN. Mean mosquito mortality for PPF-permethrin nets, across all time points, was 8.6% (CI 2.6-14.6%) higher than the standard LLIN. Fertility rates were reduced after PPF-permethrin net exposure at 1-month post distribution, but not later. Permethrin content of both types of nets remained within the target range of 20 g/kg ± 25% for 242/248 nets tested. The pyriproxyfen content of PPF-permethrin nets declined by 54%, from 10.4 g/kg (CI 10.2-10.6) to 4.7 g/kg (CI 3.5-6.0, p < 0.001) over 36 months. Net survivorship was poor, with only 13% of PPF-permethrin nets and 12% of LLINs still present in the original household after 36 months. There was no difference in the fabric integrity or survivorship between the two net types. CONCLUSION The PPF-permethrin net, Olyset Duo, met or exceeded the performance of the WHO-recommended standard LLIN (Olyset) in the current study but both net types failed the 3-year WHO bioefficacy criteria.
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Affiliation(s)
- Kobié H Toé
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Frank Mechan
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | | | - Marion Morris
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Joanna Solino
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Emile F S Tchicaya
- Swiss Centre for Scientific Research in Côte d'Ivoire, Abidjan, Côte d'Ivoire
| | - Alphonse Traoré
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Hanafy Ismail
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - James Maas
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Natalie Lissenden
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK
| | - Margaret Pinder
- Department of Biosciences, Durham University, Durham, UK.,Medical Research Council Unit, The Gambia at the London School of Hygiene and Tropical Medicine, Banjul, The Gambia
| | | | - Alfred B Tiono
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Hilary Ranson
- Vector Biology Department, Liverpool School of Tropical Medicine, Liverpool, UK.
| | - N'Falé Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
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32
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Andronescu LR, Buchwald AG, Coalson JE, Cohee L, Bauleni A, Walldorf JA, Kandangwe C, Mzilahowa T, Taylor TE, Mathanga DP, Laufer MK. Net age, but not integrity, may be associated with decreased protection against Plasmodium falciparum infection in southern Malawi. Malar J 2019; 18:329. [PMID: 31551076 PMCID: PMC6760057 DOI: 10.1186/s12936-019-2930-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 08/22/2019] [Indexed: 01/29/2023] Open
Abstract
BACKGROUND Distribution campaigns for insecticide-treated nets (ITN) have increased the use of ITNs in Malawi, but malaria prevalence remains high even among those using the nets. Previous studies have addressed ITN ownership, insecticide resistance, and frequency of ITN use as possible contributing factors to the high prevalence of malaria infection despite high ITN coverage, but have rarely considered whether the condition of the ITN, or how many people use it, impacts efficacy. This study assessed how ITN integrity, ITN age, and the number of persons sharing a net might mitigate or reduce protective efficacy among self-identified ITN users in Malawi. METHODS From 2012 to 2014, six cross-sectional surveys were conducted in both the rainy and dry seasons in southern Malawi. Data were collected on ITN use, integrity (number and size of holes), and age. Blood samples for detecting Plasmodium falciparum infection were obtained from reported ITN users over 6 months of age. Generalized linear mixed models were used to account for clustering at the household and community level. The final model controlled for gender, household eaves, and community-level infection prevalence during the rainy season. RESULTS There were 9646 ITN users with blood samples across six surveys, 15% of whom tested positive for P. falciparum infection. Among children under 5 years old, there was a 50% increased odds of P. falciparum infection among those sleeping under an ITN older than two years, compared to those using an ITN less than 2 years old (OR = 1.50; 95% CI 1.07-2.08). ITN integrity and number of individuals sharing an ITN were not associated with P. falciparum infection. CONCLUSIONS Older ITNs were associated with higher rates of P. falciparum in young children, which may indicate that insecticide concentrations play a larger role in infection prevention than the physical barrier of an ITN. ITN use was self-reported and the integrity measures lacked the precision of newer methods, suggesting a need for objective measures of ITN use and more precise assessment of ITN integrity.
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Affiliation(s)
- Liana R. Andronescu
- 0000 0001 2175 4264grid.411024.2Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W, Baltimore Street, Baltimore, MD 21201 USA
| | - Andrea G. Buchwald
- 0000 0001 2175 4264grid.411024.2Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W, Baltimore Street, Baltimore, MD 21201 USA ,0000 0001 0703 675Xgrid.430503.1Present Address: University of Colorado School of Public Health, University of Colorado, 13001 E, 17th Place, Mail Stop B119, Aurora, CO 80045 USA
| | - Jenna E. Coalson
- 0000 0001 2168 186Xgrid.134563.6Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ 85724 USA
| | - Lauren Cohee
- 0000 0001 2175 4264grid.411024.2Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W, Baltimore Street, Baltimore, MD 21201 USA
| | - Andy Bauleni
- 0000 0001 2113 2211grid.10595.38Malaria Alert Centre, University of Malawi College of Medicine, Blantyre, Malawi
| | - Jenny A. Walldorf
- 0000 0001 2175 4264grid.411024.2Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W, Baltimore Street, Baltimore, MD 21201 USA ,0000 0001 2163 0069grid.416738.fPresent Address: Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA USA
| | - Chifundo Kandangwe
- 0000 0001 2113 2211grid.10595.38Malaria Alert Centre, University of Malawi College of Medicine, Blantyre, Malawi
| | - Themba Mzilahowa
- 0000 0001 2113 2211grid.10595.38Malaria Alert Centre, University of Malawi College of Medicine, Blantyre, Malawi
| | - Terrie E. Taylor
- 0000 0001 2150 1785grid.17088.36Department of Osteopathic Medical Specialties, Michigan State University, 909 Fee Road, East Lansing, MI 48824 USA
| | - Don P. Mathanga
- 0000 0001 2113 2211grid.10595.38Malaria Alert Centre, University of Malawi College of Medicine, Blantyre, Malawi
| | - Miriam K. Laufer
- 0000 0001 2175 4264grid.411024.2Center for Vaccine Development and Global Health, University of Maryland School of Medicine, 685 W, Baltimore Street, Baltimore, MD 21201 USA
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Mwanga EP, Mmbando AS, Mrosso PC, Stica C, Mapua SA, Finda MF, Kifungo K, Kafwenji A, Monroe AC, Ogoma SB, Ngowo HS, Okumu FO. Eave ribbons treated with transfluthrin can protect both users and non-users against malaria vectors. Malar J 2019; 18:314. [PMID: 31533739 PMCID: PMC6751741 DOI: 10.1186/s12936-019-2958-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Accepted: 09/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Eave ribbons treated with spatial repellents effectively prevent human exposure to outdoor-biting and indoor-biting malaria mosquitoes, and could constitute a scalable and low-cost supplement to current interventions, such as insecticide-treated nets (ITNs). This study measured protection afforded by transfluthrin-treated eave ribbons to users (personal and communal protection) and non-users (only communal protection), and whether introducing mosquito traps as additional intervention influenced these benefits. METHODS Five experimental huts were constructed inside a 110 m long, screened tunnel, in which 1000 Anopheles arabiensis were released nightly. Eave ribbons treated with 0.25 g/m2 transfluthrin were fitted to 0, 1, 2, 3, 4 or 5 huts, achieving 0, 20, 40, 60, 80 and 100% coverage, respectively. Volunteers sat near each hut and collected mosquitoes attempting to bite them from 6 to 10 p.m. (outdoor-biting), then went indoors to sleep under untreated bed nets, beside which CDC-light traps collected mosquitoes from 10 p.m. to 6 a.m. (indoor-biting). Caged mosquitoes kept inside the huts were monitored for 24 h-mortality. Separately, eave ribbons, UV-LED mosquito traps (Mosclean) or both the ribbons and traps were fitted, each time leaving the central hut unfitted to represent non-user households and assess communal protection. Biting risk was measured concurrently in all huts, before and after introducing interventions. RESULTS Transfluthrin-treated eave ribbons provided 83% and 62% protection indoors and outdoors respectively to users, plus 57% and 48% protection indoors and outdoors to the non-user. Protection for users remained constant, but protection for non-users increased with eave ribbons coverage, peaking once 80% of huts were fitted. Mortality of mosquitoes caged inside huts with eave ribbons was 100%. The UV-LED traps increased indoor exposure to users and non-users, but marginally reduced outdoor-biting. Combining the traps and eave ribbons did not improve user protection relative to eave ribbons alone. CONCLUSION Transfluthrin-treated eave ribbons protect both users and non-users against malaria mosquitoes indoors and outdoors. The mosquito-killing property of transfluthrin can magnify the communal benefits by limiting unwanted diversion to non-users, but should be validated in field trials against pyrethroid-resistant vectors. Benefits of the UV-LED traps as an intervention alone or alongside eave ribbons were however undetectable in this study. These findings extend the evidence that transfluthrin-treated eave ribbons could complement ITNs.
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Affiliation(s)
- Emmanuel P Mwanga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania.
| | - Arnold S Mmbando
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Paul C Mrosso
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Caleb Stica
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Salum A Mapua
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Marceline F Finda
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Khamis Kifungo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Andrew Kafwenji
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - April C Monroe
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
- University of Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute (Swiss TPH), Basel, Switzerland
| | - Sheila B Ogoma
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
| | - Halfan S Ngowo
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Morogoro, Tanzania
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Public Health, University of Witwatersrand, Johannesburg, South Africa
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LLIN Evaluation in Uganda Project (LLINEUP): factors associated with childhood parasitaemia and anaemia 3 years after a national long-lasting insecticidal net distribution campaign: a cross-sectional survey. Malar J 2019; 18:207. [PMID: 31234882 PMCID: PMC6591906 DOI: 10.1186/s12936-019-2838-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2019] [Accepted: 06/14/2019] [Indexed: 12/31/2022] Open
Abstract
Background Recent reductions in malaria burden have been attributed largely to long-lasting insecticidal nets (LLINs). In March–June 2017, approximately 3 years after a national LLIN distribution campaign, a cross-sectional community survey was conducted to investigate factors associated with malaria parasitaemia and anaemia, in advance of Uganda’s 2017–2018 LLIN campaign. Methods Households from 104 clusters in 48 districts were randomly selected using two-staged cluster sampling; 50 households were enrolled per cluster. Eligible children aged 2–10 years had blood obtained for a thick blood smear and those aged 2–4 years had haemoglobin measured. Associations between outcomes and variables of interest were assessed using log-binomial regression with generalized estimating equations to adjust for household clustering. Results In total, 5196 households, 8834 children with blood smear results, and 3753 with haemoglobin results were included. Only 16% of children lived in households with adequate LLIN coverage. Overall, parasite prevalence was 26.0%, ranging from 8.0% in the South West to 53.1% in East Central. Limiting data to children 2–4 years of age, parasite prevalence was 21.4%, up from 16.9% in 2014–2015 following the national LLIN campaign. In a multivariate analysis, factors associated with parasitaemia included region (East-Central vs South-Western; adjusted prevalence ratio [aPR] 6.45, 95% CI 5.55–7.50; p < 0.001), older age (8–10 vs 2–3 years; aPR 1.57, 95% CI 1.43–1.72; p < 0.001), living in a poorer household (poorest vs least poor tercile; aPR 2.32, 95% CI 2.05–2.63; p < 0.001), one constructed of traditional materials (aPR 1.13, 95% CI 1.03–1.24; p = 0.008), or without adequate LLIN coverage (aPR 1.30, 95% CI 1.14–1.48; p < 0.001). Overall, the prevalence of anaemia (haemoglobin < 10 g/dL) was 15.1% and varied geographically. In a multivariate analysis, factors associated with anaemia included region, younger age, living in a traditional house, and parasitaemia, which was the strongest predictor (aPR 2.50, 95% CI 2.12–2.95; p < 0.001). Conclusions Three years after a national LLIN campaign, LLIN coverage was low and parasite prevalence had increased. Parasite prevalence varied widely across Uganda; older children, those living in poorer households, and those with inadequate LLIN coverage, were at highest risk of parasitaemia. LLINs may need to be distributed more frequently through mass campaigns or continuously through sustainable mechanisms. Targeting interventions to geographic areas and populations at highest risk should also be considered.
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Killeen GF, Govella NJ, Mlacha YP, Chaki PP. Suppression of malaria vector densities and human infection prevalence associated with scale-up of mosquito-proofed housing in Dar es Salaam, Tanzania: re-analysis of an observational series of parasitological and entomological surveys. Lancet Planet Health 2019; 3:e132-e143. [PMID: 30904112 DOI: 10.1016/s2542-5196(19)30035-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 02/15/2019] [Accepted: 02/18/2019] [Indexed: 06/09/2023]
Abstract
BACKGROUND In the city of Dar es Salaam, Tanzania, rapid and spontaneous scale-up of window screening occurred through purely horizontal commercial distribution systems without any public subsidies or promotion. Scale-up of window screening coincided with a planned evaluation of programmatic, vertically managed scale-up of regular larvicide application as an intervention against malaria vectors and transmission. We aimed to establish whether scale-up of window screening was associated with suppression of mosquito populations, especially for malaria vectors that strongly prefer humans as their source of blood. METHODS This study was a re-analysis of a previous observational series of epidemiological data plus new analyses of previously partly reported complementary entomological data, from Dar es Salaam. Between 2004 and 2008, six rounds of cluster-sampled, rolling, cross-sectional parasitological and questionnaire surveys were done in urban Dar es Salaam to assess the effect of larviciding and other determinants of malaria risk, such as use of bed nets and antimalarial drugs, socioeconomic status, age, sex, travel history, mosquito-proofed housing, and spending time outdoors. The effects of scaled-up larvicide application and window screening were estimated by fitting generalised linear mixed models that allowed for both spatial variation between survey locations and temporal autocorrelation within locations. We also conducted continuous longitudinal entomological surveys of outdoor human biting rates by mosquitoes and experimental measurements of mosquito host preferences. FINDINGS Best-fit models of Plasmodium falciparum malaria infection prevalence among humans were largely consistent with the results of the previous analyses. Re-analysis of previously reported epidemiological data revealed that most of the empirically fitted downward time trend in P falciparum malaria prevalence over the course of the study (odds ratio [OR] 0·04; 95% CI 0·03-0·06; p<0·0001), which was not previously reported numerically or attributed to any explanatory factor, could be plausibly explained by association with an upward trend in city-wide window screening coverage (OR 0·07; 0·05-0·09; p<0·0001) and progressive rollout of larviciding (OR 0·50; 0·41-0·60; p<0·0001). Increasing coverage of complete window screening was also associated with reduced biting densities of all taxonomic groups of mosquitoes (all p<0·0001), especially the Anopheles gambiae complex (relative rate [RR] 0·23; 95% CI 0·16-0·33) and Anopheles funestus group (RR 0·08; 0·04-0·16), which were confirmed as the most efficient vectors of malaria with strong preferences for humans over cattle. Larviciding was also associated with reduced biting densities of all mosquito taxa (p<0·0001), to an extent that varied consistently with the larvicide targeting scheme and known larval ecology of each taxon. INTERPRETATION Community-wide mosquito proofing of houses might deliver greater impacts on vector populations and malaria transmission than previously thought. The spontaneous nature of the scale-up observed here is also encouraging with regards to practicality, acceptability, and affordability in low-income settings. FUNDING United States Agency for International Development, Bill & Melinda Gates Foundation, Wellcome Trust, and Valent BioSciences LLC.
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Affiliation(s)
- Gerry F Killeen
- Ifakara Health Institute, Department of Environmental Health and Ecological Sciences, Dar es Salaam, Tanzania; Liverpool School of Tropical Medicine, Department of Vector Biology, Liverpool, UK.
| | - Nicodem J Govella
- Ifakara Health Institute, Department of Environmental Health and Ecological Sciences, Dar es Salaam, Tanzania
| | - Yeromin P Mlacha
- Ifakara Health Institute, Department of Environmental Health and Ecological Sciences, Dar es Salaam, Tanzania
| | - Prosper P Chaki
- Ifakara Health Institute, Department of Environmental Health and Ecological Sciences, Dar es Salaam, Tanzania
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Gonahasa S, Maiteki-Sebuguzi C, Rugnao S, Dorsey G, Opigo J, Yeka A, Katureebe A, Kyohere M, Lynd A, Hemingway J, Donnelly M, Kamya MR, Staedke SG. LLIN Evaluation in Uganda Project (LLINEUP): factors associated with ownership and use of long-lasting insecticidal nets in Uganda: a cross-sectional survey of 48 districts. Malar J 2018; 17:421. [PMID: 30424775 PMCID: PMC6234693 DOI: 10.1186/s12936-018-2571-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 11/03/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are a key malaria control intervention. To investigate factors associated with ownership and use of LLINs in Uganda, a cross-sectional community survey was conducted in March-June 2017, approximately 3 years after a national Universal Coverage Campaign (UCC). METHODS Households from 104 clusters (health sub-districts) in 48 districts were randomly selected using two-staged cluster sampling; 50 households were enrolled per cluster. Outcomes were household ownership of LLINs (at least one LLIN), adequate LLIN coverage (at least one LLIN per 2 residents), and use of LLINs (resident slept under a LLIN the previous night). Associations between variables of interest and outcomes were made using multivariate logistic regression. RESULTS In total, 5196 households, with 29,627 residents and 6980 bed-nets, were included in the analysis. Overall, 65.0% of households owned at least one LLIN (down from 94% in 2014). In the adjusted analysis, factors most strongly associated with LLIN ownership were living in a wealthier household (highest tercile vs lowest; adjusted odds ratio [aOR] 1.94, 95% CI 1.66-2.28, p < 0.001) and time since the last UCC (29-37 vs 42-53 months; aOR 1.91, 95% CI 1.60-2.28, p < 0.001). Only 17.9% of households had adequate LLIN coverage (down from 65% in 2014). Factors most strongly associated with adequate coverage were fewer residents (2-4 vs ≥ 7; aOR 6.52, 95% CI 5.13-8.29, p < 0.001), living in a wealthier household (highest tercile vs lowest; aOR: 2,32, 95% CI 1.88-2.85, p < 0.001) and time since the last UCC (29-37 vs 42-53 months; aOR 2.13, 95% CI 1.61-2.81, p < 0.001). Only 39.5% of residents used a LLIN the previous night. Age was strongly associated with LLIN use, as were household wealth and time since the last UCC. Children < 5 years (44.7%) and residents > 15 years (44.1%) were more likely to use nets than children aged 5-15 years (30.7%; < 5 years: aOR 1.71, 95% CI 1.62-1.81, p < 0.001; > 15 years: aOR 1.37, 95% CI 1.29-1.45, p < 0.001). CONCLUSIONS Long-lasting insecticidal net ownership and coverage have reduced markedly in Uganda since the last net distribution campaign in 2013/14. Houses with many residents, poorer households, and school-aged children should be targeted to improve LLIN coverage and use. Trial registration This study is registered with ISRCTN (17516395).
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Affiliation(s)
- Samuel Gonahasa
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda.
| | - Catherine Maiteki-Sebuguzi
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda.,National Malaria Control Programme, Uganda Ministry of Health, Kampala, Uganda
| | - Sheila Rugnao
- University of California, San Francisco, San Francisco, CA, 94110, USA
| | - Grant Dorsey
- University of California, San Francisco, San Francisco, CA, 94110, USA
| | - Jimmy Opigo
- National Malaria Control Programme, Uganda Ministry of Health, Kampala, Uganda
| | - 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
| | - Amy Lynd
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Janet Hemingway
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Martin Donnelly
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK
| | - Moses R Kamya
- Infectious Diseases Research Collaboration, 2C Nakasero Hill Road, Kampala, Uganda
| | - Sarah G Staedke
- London School of Hygiene & Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
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Mboma ZM, Dillip A, Kramer K, Koenker H, Greer G, Lorenz LM. 'For the poor, sleep is leisure': understanding perceptions, barriers and motivators to mosquito net care and repair in southern Tanzania. Malar J 2018; 17:375. [PMID: 30348167 PMCID: PMC6196435 DOI: 10.1186/s12936-018-2528-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 10/15/2018] [Indexed: 01/08/2023] Open
Abstract
Background The rate of physical deterioration of long-lasting insecticidal nets (LLINs) varies by household practices, net brand and environment. One way to sustain the protection provided by LLINs against malaria is through day-to-day care, and repairing holes as and when they occur. To ensure LLIN coverage is high between mass campaigns and, as international donor funds decrease, personal responsibility to maintain nets in good condition is becoming more important. This study aimed to understand local barriers and motivators to net care and repair in southern Tanzania in a community that receives free LLINs through a school-based distribution mechanism. Methods Qualitative research methods were applied in a rural and peri-urban village in Ruangwa district. Focus group discussions (FGDs) were conducted for five groups of 8–12 participants; (1) key informants, (2) young men (18–24 years old), (3) women (> 18 years) with children under the age of five, (4) older men (> 25 years), and (5) older women with or without children (> 25 years). In each village, five men, five women with or without children, and five women with children under the age of five were recruited for in-depth interviews (IDIs). After each IDI and FGD with women with young children, participants were guided through a participatory activity. The study also counted the number and size of holes in nets currently used by IDI participants to determine their physical degradation status. Results A general willingness to care and repair mosquito nets was observed in Ruangwa district for the love of a good night’s sleep free of mosquito bites or noises. Net care was preferred over repair, especially among women who were the primary caretakers. The main motivation to look after nets was protection against mosquito bites and malaria. Washing nets occurred as frequently as every other week in some households to ensure cleanliness, which prevented other dirt-related problems such as sneezing and headaches. Barriers to net care included care not being a priority in the day-to-day activities and lack of net retreatment kits. Net repair was reported to be a temporary measure and necessary as soon as a hole was identified. However, during the net assessment and participatory activity, it became clear that people did not actually repair smaller holes. Protection against mosquitoes, malaria and cost saving from replacing nets were identified as motivators for net repair. Barriers to net repair included it not being a priority to repair holes that could be tucked under the mattress and lack of knowledge on when to repair nets. Conclusion In Ruangwa, net care was defined as overall net maintenance, such as cleanliness, and not directly associated with the prevention of damage as reported in other studies. Net repair was reported as a temporary measure before the acquisition of a new net, hence not a priority in a busy household. Inconsistencies were observed between reported intentions to repair mosquito nets and current net condition. Targeted education through health facilities and community change agents are potential means to overcome barriers to net care and repair.
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Affiliation(s)
- Zawadi M Mboma
- Ifakara Health Institute, Dar-es-Salaam, Tanzania. .,London School of Hygiene and Tropical Medicine, London, UK.
| | - Angel Dillip
- Ifakara Health Institute, Dar-es-Salaam, Tanzania
| | - Karen Kramer
- National Malaria Control Programme, Dar-es-Salaam, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Hannah Koenker
- PMI VectorWorks, Johns Hopkins Center for Communication Programs, Baltimore, MD, USA
| | - George Greer
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Dar es Salaam, Tanzania
| | - Lena M Lorenz
- Ifakara Health Institute, Dar-es-Salaam, Tanzania.,London School of Hygiene and Tropical Medicine, London, UK
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Bed nets used to protect against malaria do not last long in a semi-arid area of Ethiopia: a cohort study. Malar J 2018; 17:239. [PMID: 29925371 PMCID: PMC6011348 DOI: 10.1186/s12936-018-2391-5] [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: 05/26/2018] [Accepted: 06/14/2018] [Indexed: 11/29/2022] Open
Abstract
Background Long-lasting insecticidal nets (LLINs) are a key tool for malaria prevention and control. Currently, the recommended serviceable life of an LLIN is 3 years under field conditions. However, field studies show considerable variation in LLIN lifespan, from less than 2 years to more than 4 years. This study aimed to determine the attrition, physical integrity, functional survival, and bio-efficacy of LLINs under field conditions in south-central Ethiopia. Methods In October 2014, 7740 LLINs (PermaNet® 2.0) were distributed to 3006 households. Among the distributed LLINs, a cohort study involving 1532 LLINs in 659 households was carried out from October 2014 to November 2016. Data were collected every 6 months by observation, and through interviews with the heads of households. The proportional hole index was used to categorize LLINs as either serviceable or torn. In addition, 120 randomly selected LLINs were tested for bio-efficacy. Results The overall attrition of LLINs was 96% (n = 993) during the study period. The nets’ attrition was mainly due to disposal (64.2%; n = 638). The proportion of LLINs with a hole size 0.5 cm or larger was 79.5% after 24 months. The use of the net on the previous night and having a clean net were associated with a good physical integrity. However, living in a household more than 1 km away from the mosquitoes’ breeding site was associated with poor physical integrity. By the 24th month, only 4% of the nets met the criteria for functional survival. The median functional survival time of the nets was 12 months. A longer functional survival was associated with having a clean net, and shorter survival was associated with living in a household more than 1 km away from the mosquitoes’ breeding site. The PermaNet® 2.0 met the criteria of effective bio-efficacy up to month 24 after distribution. Conclusions The study showed that the median serviceable life of LLINs is only 12 months. However, the bio-efficacy of the LLINs is acceptable for at least 24 months. Therefore, stronger and more efficient LLINs need to be developed for conditions similar to those studied here.
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Mboma ZM, Overgaard HJ, Moore S, Bradley J, Moore J, Massue DJ, Kramer K, Lines J, Lorenz LM. Mosquito net coverage in years between mass distributions: a case study of Tanzania, 2013. Malar J 2018; 17:100. [PMID: 29490649 PMCID: PMC5831856 DOI: 10.1186/s12936-018-2247-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 02/22/2018] [Indexed: 11/13/2022] Open
Abstract
Background The Government of Tanzania is the main source of long-lasting insecticidal nets (LLINs) for its population. Mosquito nets (treated and untreated) are also available in the commercial market. To sustain investments and health gains in the fight against malaria, it is important for the National Malaria Control Programme to monitor LLIN coverage especially in the years between mass distributions and to understand what households do if their free nets are deemed unusable. The aim of this paper was to assess standard LLIN indicators by wealth status in Tanzania in 2013, 2 years after the last mass campaign in 2011, and extend the analysis to untreated nets (UTNs) to investigate how households adapt when nets are not continuously distributed. Methods Between October–December 2013, a household survey was conducted in 3398 households in eight districts in Tanzania. Using the Roll Back Malaria indicators, the study analysed: (1) household net ownership; (2) access to nets; (3) population net use and (4) net use:access ratio. Outcomes were calculated for LLINs and UTNs. Results were analysed by socio-economic quintiles and by district. Results Only three of the eight districts had household LLIN ownership of more than 80%. In 2013, less than a quarter of the households had one LLIN for every two people and only half of the population had access to an LLIN. Only the wealthier quintiles increased their net ownership and access to levels above 80% through the addition of UTNs. Overall net use of the population was low (LLINs: 32.8%; UTNs: 9.5%) and net use:access ratio was below target level (LLINs: 0.66; UTN: 0.50). Both measures varied significantly by district. Conclusions Two years after the last mass campaign, the percentage of households or population with access to LLINs was low. These findings indicate the average rate at which households in Tanzania lose their nets is higher than the rate at which they acquire new nets. The wealthiest households topped up their household net ownership with UTNs. Efforts to make LLINs available through commercial markets should be promoted, so those who can afford to buy nets purchase LLINs rather than UTNs. Net use was low around 40% and mostly explained by lack of access to nets. However, the use:access ratio was poor in Mbozi and Kahama districts warranting further investigations to understand other barriers to net use. Electronic supplementary material The online version of this article (10.1186/s12936-018-2247-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zawadi M Mboma
- Ifakara Health Institute, Bagamoyo, Tanzania.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway.
| | - Sarah Moore
- Ifakara Health Institute, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, UK
| | - Jason Moore
- Ifakara Health Institute, Bagamoyo, Tanzania.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Dennis J Massue
- Ifakara Health Institute, Bagamoyo, Tanzania.,Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland.,National Institute for Medical Research, Muheza, Tanzania
| | - Karen Kramer
- Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Petersplatz 1, 4003, Basel, Switzerland
| | - Jo Lines
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
| | - Lena M Lorenz
- Ifakara Health Institute, Bagamoyo, Tanzania.,Department of Disease Control, London School of Hygiene and Tropical Medicine, London, UK
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Minta AA, Landman KZ, Mwandama DA, Shah MP, Eng JLV, Sutcliffe JF, Chisaka J, Lindblade KA, Mathanga DP, Steinhardt LC. The effect of holes in long-lasting insecticidal nets on malaria in Malawi: results from a case-control study. Malar J 2017; 16:394. [PMID: 28969632 PMCID: PMC5625742 DOI: 10.1186/s12936-017-2033-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 09/18/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are a cornerstone of malaria prevention. Holes develop in LLINs over time and compromise their physical integrity, but how holes affect malaria transmission risk is not well known. METHODS After a nationwide mass LLIN distribution in July 2012, a study was conducted to assess the relationship between LLIN damage and malaria. From March to September 2013, febrile children ages 6-59 months who consistently slept under LLINs (every night for 2 weeks before illness onset) were enrolled in a case-control study at Machinga District Hospital outpatient department. Cases were positive for Plasmodium falciparum asexual parasites by microscopy while controls were negative. Digital photographs of participants' LLINs were analysed using an image-processing programme to measure holes. Total hole area was classified by quartiles and according to the World Health Organization's proportionate hole index (pHI) cut-offs [< 79 cm2 (good), 80-789 cm2 (damaged), and > 790 cm2 (too torn)]. Number of holes by location and size, and total hole area, were compared between case and control LLINs using non-parametric analyses and logistic regression. RESULTS Of 248 LLINs analysed, 97 (39%) were from cases. Overall, 86% of LLINs had at least one hole. The median number of holes of any size was 9 [interquartile range (IQR) 3, 22], and most holes were located in the lower halves of the nets [median 7 (IQR 2, 16)]. There were no differences in number or location of holes between LLINs used by cases and controls. The median total hole area was 10 cm2 (IQR 2, 125) for control LLINs and 8 cm2 (IQR 2, 47) for case LLINs (p = 0.10). Based on pHI, 109 (72%) control LLINs and 83 (86%) case LLINs were in "good" condition. Multivariable modeling showed no association between total hole area and malaria, controlling for child age, caregiver education, and iron versus thatched roof houses. CONCLUSIONS LLIN holes were not associated with increased odds of malaria in this study. However, most of the LLINs were in relatively good condition 1 year after distribution. Future studies should examine associations between LLIN holes and malaria risk with more damaged nets.
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Affiliation(s)
- Anna A Minta
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA. .,Epidemic Intelligence Service, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA.
| | - Keren Z Landman
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Dyson A Mwandama
- Malaria Alert Centre, University of Malawi College of Medicine, Private Bag 360, Blantyre, Malawi
| | - Monica P Shah
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Jodi L Vanden Eng
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - James F Sutcliffe
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Joseph Chisaka
- Malaria Alert Centre, University of Malawi College of Medicine, Private Bag 360, Blantyre, Malawi
| | - Kim A Lindblade
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
| | - Don P Mathanga
- Malaria Alert Centre, University of Malawi College of Medicine, Private Bag 360, Blantyre, Malawi
| | - Laura C Steinhardt
- Malaria Branch, Division of Parasitic Diseases and Malaria, Centers for Disease Control and Prevention, 1600 Clifton Road, Atlanta, GA, 30329, USA
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