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Charlwood JD. Uneasy bedfellows: Public-Private partnerships for malaria control. MALARIAWORLD JOURNAL 2024; 15:9. [PMID: 38711910 PMCID: PMC11070747 DOI: 10.5281/zenodo.11046816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
It is argued that reducing poverty is likely to alleviate malaria transmission and that the way to do this is by reducing inequality. The present capitalist system (as opposed to a straightforward market) tends to erode equality and promote profit over product. This may extend to the manufacture of bednets, bought by agencies rather than individual consumers, whose products may suffer from built in obsolescence. It is argued that better quality nets that can be re-impregnated locally are both desired and required. Derek Charlwood (aka Mzshensy#1) started his career as a medical entomologist in 1974 as a Research Assistant in the laboratory of the legendary Mick Gillies. By 2012 he had risen to become a Senior Research Assistant working for the Liverpool School of Tropical Medicine and so he is definitely ascending the career ladder. He has worked in numerous malaria endemic countries including Brazil, Papua New Guinea, Tanzania, Cambodia, São Tomé and Príncipe, Mozambique and Eritrea.
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Affiliation(s)
- Jacques D Charlwood
- Global Health and Tropical Medicine, Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Rua da Junqueira 100 , 1349-008 Lisbon, Portugal
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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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Wheldrake A, Guillemois E, Arouni H, Chetty V, Zappa E, Russell SJ. Physical durability: are bed nets getting any stronger? Malar J 2024; 23:19. [PMID: 38218962 PMCID: PMC10787957 DOI: 10.1186/s12936-023-04832-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Accepted: 12/29/2023] [Indexed: 01/15/2024] Open
Abstract
BACKGROUND For at least a decade, concerns have been raised about the physical durability of insecticide-treated nets (ITNs) and their ability to remain in good condition for at least three years. To discover if the resistance to damage (RD) of ITNs has improved or not, the RD scores of ITNs sampled in 2013 and 2020 were compared. METHODS The RD scores and disaggregated textile performance data for nine ITNs recommended by the WHO pesticide evaluation scheme (WHOPES) measured in 2013 were compared with WHO-prequalified ITNs sampled in 2020. This included assessment of newer ITNs not available in 2013, to determine the extent to which product development has led to performance improvements across all available ITNs in the intervening years. RESULTS The resistance to damage of ITNs has not generally improved from 2013 to 2020, and in some cases performance is worse. The average RD score of comparable ITNs brands decreased from 40 in 2013 to 36 in 2020. Of the nets available in 2020, only two of the twenty-four ITN products tested achieved an RD score of > 50, while six ITNs had very low RD scores of < 30, highlighting a serious inherent, and literal weakness in many WHO-prequalified ITNs. CONCLUSIONS The long-term physical durability of ITN products cannot be expected to improve while their resistance to damage remains so low, and major upgrades to the performance standards of textile materials used to make ITNs, as well as incentives to develop stronger ones are urgently required.
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Affiliation(s)
- Amy Wheldrake
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Estelle Guillemois
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Hamidreza Arouni
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Vera Chetty
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Edoardo Zappa
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK
| | - Stephen J Russell
- Nonwovens Innovation & Research Institute Ltd, Innovation House, Gibraltar Island Rd, Leeds, West Yorkshire, LS10 1RJ, UK.
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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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Azizi S, Martin J, Mbewe NJ, Msapalla A, Mwacha S, Joram A, Mawa B, Kaaya RD, Kitau J, Mosha F, Matowo J, Protopopoff N. Evaluation of Durability as a Function of Fabric Strength and Residual Bio-Efficacy for the Olyset Plus and Interceptor G2 LLINs after 3 Years of Field Use in Tanzania. Trop Med Infect Dis 2023; 8:379. [PMID: 37624317 PMCID: PMC10459516 DOI: 10.3390/tropicalmed8080379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Revised: 07/08/2023] [Accepted: 07/10/2023] [Indexed: 08/26/2023] Open
Abstract
Long-lasting insecticidal nets (LLINs) are prone to reduction in insecticide content and physical strength due to repeated washes and usage. The significant loss to these features jeopardizes their protection against bites from malaria vectors. Insecticide washout is attributed to routine use, friction, and washing, while fabric damage is associated with routine use in households. To maintain coverage and cost-effectiveness, nets should maintain optimal bio-efficacy and physical strength for at least 3 years after distribution. In this study, the bio-efficacy and fabric strength of Olyset plus (OP) LLINs and Interceptor G2 (IG2), that were used for 3 years, were assessed in comparison to untreated and new unwashed counterparts. Both IG2 and OP LLINs (unused, laboratory-washed, and 36 months used) were able to induce significant mortality and blood feeding inhibition (BFI) to mosquitoes compared to the untreated nets. Significantly higher mortality was induced by unused IG2 LLIN and OP LLIN compared to their 36-month-old counterparts against both pyrethroid resistant and susceptible Anopheles gambiae sensu strito. The physical strength of the IG2 LLIN was higher than that of the Olyset Plus LLIN with a decreasing trend from unwashed, laboratory-washed to community usage (36 months old). Malaria control programs should consider bio-efficacy and physical integrity prior to an LLINs' procurement and replacement plan.
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Affiliation(s)
- Salum Azizi
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Jackline Martin
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Njelembo J. Mbewe
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Agness Msapalla
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Silvia Mwacha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Amandus Joram
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Benson Mawa
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Robert Diotrephes Kaaya
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Jovin Kitau
- Country Office, World Health Organization, Dar es Salaam 255, Tanzania;
| | - Franklin Mosha
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Johnson Matowo
- Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi 255, Tanzania (S.M.); (R.D.K.); (F.M.); (J.M.)
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
| | - Natacha Protopopoff
- Pan African Malaria Vector Research Consortium, Moshi 255, Tanzania (N.P.)
- Department of Disease Control, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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Hilton ER, Rabeherisoa S, Ramandimbiarijaona H, Rajaratnam J, Belemvire A, Kapesa L, Zohdy S, Dentinger C, Gandaho T, Jacob D, Burnett S, Razafinjato C. Using routine health data to evaluate the impact of indoor residual spraying on malaria transmission in Madagascar. BMJ Glob Health 2023; 8:e010818. [PMID: 37463785 PMCID: PMC10357738 DOI: 10.1136/bmjgh-2022-010818] [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: 09/27/2022] [Accepted: 06/17/2023] [Indexed: 07/20/2023] Open
Abstract
INTRODUCTION Indoor residual spraying (IRS) and insecticide-treated bed nets (ITNs) are cornerstone malaria prevention methods in Madagascar. This retrospective observational study uses routine data to evaluate the impacts of IRS overall, sustained IRS exposure over multiple years and level of spray coverage (structures sprayed/found) in nine districts where non-pyrethroid IRS was deployed to complement standard pyrethroid ITNs from 2017 to 2020. METHODS Multilevel negative-binomial generalised linear models were fit to estimate the effects of IRS exposure overall, consecutive years of IRS exposure and spray coverage level on monthly all-ages population-adjusted malaria cases confirmed by rapid diagnostic test at the health facility level. The study period extended from July 2016 to June 2021. Facilities with missing data and non-geolocated communes were excluded. Facilities in IRS districts were matched with control facilities by propensity score analysis. Models were controlled for ITN survivorship, mass drug administration coverage, precipitation, enhanced vegetation index, seasonal effects and district. Predicted cases under a counterfactual no IRS scenario and number of cases averted by IRS were estimated using the fitted models. RESULTS Exposure to IRS overall reduced case incidence by an estimated 30.3% from 165.8 cases per 1000 population (95% CI=139.7 to 196.7) under a counterfactual no IRS scenario, to 114.3 (95% CI=96.5 to 135.3) over 12 months post-IRS campaign in nine districts. A third year of IRS reduced malaria cases 30.9% more than a first year (incidence rate ratio (IRR)=0.578, 95% CI=0.578 to 0.825, p<0.001) and 26.7% more than a second year (IRR=0.733, 95% CI=0.611 to 0.878, p=0.001). There was no significant difference between the first and second year (p>0.05). Coverage of 86%-90% was associated with a 19.7% reduction in incidence (IRR=0.803, 95% CI=0.690 to 0.934, p=0.005) compared with coverage ≤85%, although these results were not robust to sensitivity analysis. CONCLUSION This study demonstrates that non-pyrethroid IRS appears to substantially reduce malaria incidence in Madagascar and that sustained implementation of IRS over three years confers additional benefits.
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Affiliation(s)
| | - Saraha Rabeherisoa
- Programme National de Lutte Contre le Paludisme, Ministère de la Santé Publique, Antananarivo, Madagascar
| | - Herizo Ramandimbiarijaona
- Programme National de Lutte Contre le Paludisme, Ministère de la Santé Publique, Antananarivo, Madagascar
| | - Julie Rajaratnam
- Center for Digital and Data Excellence, PATH, Seattle, Washington, USA
| | - Allison Belemvire
- US Agency for International Development, US President's Malaria Initiative, Washington, District of Columbia, USA
| | - Laurent Kapesa
- US Agency for International Development, US President's Malaria Initiative, Antananarivo, Madagascar
| | - Sarah Zohdy
- Entomology Branch, US Centers for Disease Control and Prevention, US President's Malaria Initiative, Atlanta, Georgia, USA
| | - Catherine Dentinger
- Entomology Branch, US Centers for Disease Control and Prevention, US President's Malaria Initiative, Atlanta, Georgia, USA
| | - Timothee Gandaho
- PMI VectorLink Project, Abt Associates, Rockville, Maryland, USA
| | - Djenam Jacob
- PMI VectorLink Project, Abt Associates, Rockville, Maryland, USA
| | - Sarah Burnett
- PMI VectorLink Project, PATH, Washington, District of Columbia, USA
| | - Celestin Razafinjato
- Programme National de Lutte Contre le Paludisme, Ministère de la Santé Publique, Antananarivo, Madagascar
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Koenker H, Yukich J, Erskine M, Opoku R, Sternberg E, Kilian A. How many mosquito nets are needed to maintain universal coverage: an update. Malar J 2023; 22:200. [PMID: 37391703 DOI: 10.1186/s12936-023-04609-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/26/2023] [Indexed: 07/02/2023] Open
Abstract
BACKGROUND Insecticide-treated nets (ITNs) have served as the cornerstone of malaria vector control in sub-Saharan Africa for the past two decades. Over 2.5 billion ITNs have been delivered since 2004 primarily through periodic mass distribution campaigns scheduled at approximately three-year intervals, aligning with the expected lifespan of nets. Recent work indicates that ITN retention times are less than two years in most countries, raising key questions for quantification approaches and delivery frequency for ITN distribution. This paper models several quantification approaches for five typical ITN distribution strategies, estimates the proportion of the population with access to an ITN, and presents recommended quantification approaches to meet global targets for ITN access and use. METHODS A stock and flow model with annual timesteps was used to model ITN distribution and resulting ITN access for 2020-2035 under five scenarios in 40 countries: (1) three-year mass campaigns, (2) full-scale annual continuous distribution, (3) three-year mass campaigns plus continuous distribution in the years between campaigns, (4) three-year mass campaigns at different quantification approaches, (5) two-year mass campaigns at different quantification approaches. All scenarios included ITN distribution to pregnant women at antenatal clinics and infants at immunization visits. RESULTS The current status quo of conducting mass campaigns every three years using a population/1.8 quantifier is insufficient to achieve or maintain targets of 80% population access to ITNs in most malaria-endemic countries, given most estimated retention times are less than three years. Tailored three- or two-year mass campaigns were less efficient than annual continuous distribution strategies in nearly all settings. For countries with at least 2.5 year median ITN retention times, full scale continuous distribution provided better ITN access while needing 20-23% fewer ITNs compared to current mass campaigns. CONCLUSION Given variation in ITN retention times across countries, tailored quantification approaches for mass campaigns and continuous distribution strategies are warranted. Continuous distribution strategies are likely to offer more efficient ways to maintain ITN coverage, with fewer nets, where ITN retention times are at least two and a half years. National malaria programmes and their funding partners should work to increase the number of ITNs available to those vulnerable to malaria, while at the same time working to extend the useful life of these critical commodities.
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Affiliation(s)
| | - Josh Yukich
- Center for Applied Malaria Research and Evaluation, Tulane University, New Orleans, USA
| | - Marcy Erskine
- International Federation of Red Cross and Red Crescent Societies, Geneva, Switzerland
| | - Robert Opoku
- International Federation of Red Cross and Red Crescent Societies, Nairobi, Kenya
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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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10
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Brake S, Gomez-Maldonado D, Hummel M, Zohdy S, Peresin MS. Understanding the current state-of-the-art of long-lasting insecticide nets and potential for sustainable alternatives. CURRENT RESEARCH IN PARASITOLOGY & VECTOR-BORNE DISEASES 2022; 2:100101. [PMID: 36248356 PMCID: PMC9562956 DOI: 10.1016/j.crpvbd.2022.100101] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Revised: 09/13/2022] [Accepted: 09/14/2022] [Indexed: 11/23/2022]
Abstract
Long-lasting insecticide-treated nets (LLINs) are widely distributed to communities where malaria is a major cause of mortality, especially to those under the age of 5 years-old. To protect people from this illness, LLINs provide physical and chemical barriers by containing insecticides within the matrix of the polymer fibers or on the surface. Synthetic polymers including polyethylene and polyester are common material choices for these nets, and pyrethroids, along with other additives, are the insecticides of choice for this application. Many studies have shown the effectiveness of these nets on the impact of malaria is highly significant, but there is a demand for more durable nets that last longer than only a few years as the available products are rated for 2–3 years of use. Improvements in this area would increase cost effectiveness, because better durability would reduce the frequency of manufacturing and worldwide shipping. Additionally, due to the plastic fibers, the waste can build quickly, damaging the environment. To deal with the sustainability and durability issues, biodegradable and renewable materials should be chosen as an alternative. LLINs are important for malaria control, but they require a sustainable and durable alternative to synthetic polymers. LLINs are made by extrusion of pyrethroids and synthetic polymers or by coating. The current LLINs include important active ingredients to improve insecticidal activity. Bio-based polymers have the potential to be used to develop a superior LLIN to those available currently.
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11
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Mbwambo SG, Bubun N, Mbuba E, Moore J, Mbina K, Kamande D, Laman M, Mpolya E, Odufuwa OG, Freeman T, Karl S, Moore SJ. Comparison of cone bioassay estimates at two laboratories with different Anopheles mosquitoes for quality assurance of pyrethroid insecticide-treated nets. Malar J 2022; 21:214. [PMID: 35799172 PMCID: PMC9264565 DOI: 10.1186/s12936-022-04217-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 06/11/2022] [Indexed: 11/16/2022] Open
Abstract
Background Quality assurance (QA) of insecticide-treated nets (ITNs) delivered to malaria-endemic countries is conducted by measuring physiochemical parameters, but not bioefficacy against malaria mosquitoes. This study explored utility of cone bioassays for pre-delivery QA of pyrethroid ITNs to test the assumption that cone bioassays are consistent across locations, mosquito strains, and laboratories. Methods Double-blinded bioassays were conducted on twenty unused pyrethroid ITNs of 4 brands (100 nets, 5 subsamples per net) that had been delivered for mass distribution in Papua New Guinea (PNG) having passed predelivery inspections. Cone bioassays were performed on the same net pieces following World Health Organization (WHO) guidelines at the PNG Institute of Medical Research (PNGIMR) using pyrethroid susceptible Anopheles farauti sensu stricto (s.s.) and at Ifakara Health Institute (IHI), Tanzania using pyrethroid susceptible Anopheles gambiae s.s. Additionally, WHO tunnel tests were conducted at IHI on ITNs that did not meet cone bioefficacy thresholds. Results from IHI and PNGIMR were compared using Spearman’s Rank correlation, Bland–Altman (BA) analysis and analysis of agreement. Literature review on the use of cone bioassays for unused pyrethroid ITNs testing was conducted. Results In cone bioassays, 13/20 nets (65%) at IHI and 8/20 (40%) at PNGIMR met WHO bioefficacy criteria. All nets met WHO bioefficacy criteria on combined cone/tunnel tests at IHI. Results from IHI and PNGIMR correlated on 60-min knockdown (KD60) (rs = 0.6,p = 0.002,n = 20) and 24-h mortality (M24) (rs = 0.9,p < 0.0001,n = 20) but BA showed systematic bias between the results. Of the 5 nets with discrepant result between IHI and PNGIMR, three had confidence intervals overlapping the 80% mortality threshold, with averages within 1–3% of the threshold. Including these as a pass, the agreement between the results to predict ITN failure was good with kappa = 0.79 (0.53–1.00) and 90% accuracy. Conclusions Based on these study findings, the WHO cone bioassay is a reproducible bioassay for ITNs with > 80% M24, and for all ITNs provided inherent stochastic variation and systematic bias are accounted for. The literature review confirms that WHO cone bioassay bioefficacy criteria have been previously achieved by all pyrethroid ITNs (unwashed), without the need for additional tunnel tests. The 80% M24 threshold remains the most reliable indicator of pyrethroid ITN quality using pyrethroid susceptible mosquitoes. In the absence of alternative tests, cone bioassays could be used as part of pre-delivery QA.
Supplementary Information The online version contains supplementary material available at 10.1186/s12936-022-04217-3.
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Affiliation(s)
- Stephen G Mbwambo
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania. .,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania. .,Sokoine RRH, Ministry of Health, Lindi, Tanzania. .,Regional Health Management Team, P.O Box 1011, Lindi, Tanzania.
| | - Nakei Bubun
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mbuba
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Jason Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
| | - Kasiani Mbina
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania
| | - Dismas Kamande
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Moses Laman
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea
| | - Emmanuel Mpolya
- Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania
| | - Olukayode G Odufuwa
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland.,MRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Tim Freeman
- Rotarian Against Malaria, P.O Box 3686, Boroko, NCD 111, Papua New Guinea
| | - Stephan Karl
- Vector Borne Disease Unit, PNG Institute of Medical Research, Madang Province 511, P.O Box 378, Madang, Papua New Guinea.,Australian Institute of Tropical Health and Medicine, James Cook University, 1/14-88 McGregor Road, Smithfield, QLD, 4870, Australia
| | - Sarah J Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo, Tanzania.,Nelson Mandela Africa Institution of Science and Technology, Arusha, Tanzania.,University of Basel, Basel, Switzerland.,Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute (Swiss TPH, Allschwil, Kreuzstrasse 2, 4123, , Basel, Switzerland
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12
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Lees RS, Armistead JS, Azizi S, Constant E, Fornadel C, Gimnig JE, Hemingway J, Impoinvil D, Irish SR, Kisinza W, Lissenden N, Mawejje HD, Messenger LA, Moore S, Ngufor C, Oxborough R, Protopopoff N, Ranson H, Small G, Wagman J, Weetman D, Zohdy S, Spiers A. Strain Characterisation for Measuring Bioefficacy of ITNs Treated with Two Active Ingredients (Dual-AI ITNs): Developing a Robust Protocol by Building Consensus. INSECTS 2022; 13:434. [PMID: 35621770 PMCID: PMC9144861 DOI: 10.3390/insects13050434] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Revised: 04/21/2022] [Accepted: 04/22/2022] [Indexed: 02/04/2023]
Abstract
Durability monitoring of insecticide-treated nets (ITNs) containing a pyrethroid in combination with a second active ingredient (AI) must be adapted so that the insecticidal bioefficacy of each AI can be monitored independently. An effective way to do this is to measure rapid knock down of a pyrethroid-susceptible strain of mosquitoes to assess the bioefficacy of the pyrethroid component and to use a pyrethroid-resistant strain to measure the bioefficacy of the second ingredient. To allow robust comparison of results across tests within and between test facilities, and over time, protocols for bioefficacy testing must include either characterisation of the resistant strain, standardisation of the mosquitoes used for bioassays, or a combination of the two. Through a series of virtual meetings, key stakeholders and practitioners explored different approaches to achieving these goals. Via an iterative process we decided on the preferred approach and produced a protocol consisting of characterising mosquitoes used for bioefficacy testing before and after a round of bioassays, for example at each time point in a durability monitoring study. We present the final protocol and justify our approach to establishing a standard methodology for durability monitoring of ITNs containing pyrethroid and a second AI.
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Affiliation(s)
- Rosemary S. Lees
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Jennifer S. Armistead
- U.S. President’s Malaria Initiative (PMI), U.S. Agency for International Development (USAID), Washington, DC 20547, USA;
| | - Salum Azizi
- KCMUCo-PAMVERC Test Facility, Department of Medical Parasitology and Entomology, Kilimanjaro Christian Medical University College, Moshi P.O. Box 2240, Tanzania;
| | - Edi Constant
- Centre Suisse de Recherches Scientifiques (CSRS), Abidjan 1303, Côte d’Ivoire;
| | - Christen Fornadel
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (C.F.); (G.S.)
| | - John E. Gimnig
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
| | - Janet Hemingway
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Daniel Impoinvil
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - Seth R. Irish
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - William Kisinza
- Amani Research Centre, National Institute for Medical Research, Muheza P.O. Box 81, Tanzania;
| | - Natalie Lissenden
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
| | - Henry D. Mawejje
- Infectious Diseases Research Collaboration (IDRC), Plot 2C Nakasero Hill Road, Kampala P.O. Box 7475, Uganda;
| | - Louisa A. Messenger
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
| | - Sarah Moore
- Vector Control Product Testing Unit (VCPTU), Environmental Health and Ecological Science Department, Ifakara Health Institute, Bagamoyo P.O. Box 74, Tanzania;
- Vector Biology Unit, Department of Epidemiology and Public Health, Swiss Tropical & Public Health Institute, Kreuzstrasse 2, Allschwil, 4123 Basel, Switzerland
- Faculty of Science, University of Basel, Petersplatz 1, 4001 Basel, Switzerland
- Nelson Mandela African Institute of Science and Technology (NM-AIST), Tengeru P.O. Box 447, Tanzania
| | - Corine Ngufor
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
- Centre de Recherche Entomologique de Cotonou, Cotonou BP 2604, Benin
| | - Richard Oxborough
- PMI VectorLink Project, Abt Associates, 6130 Executive Blvd., Rockville, MD 20852, USA;
| | - Natacha Protopopoff
- Department of Disease Control, Faculty of Infectious Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK; (L.A.M.); (C.N.); (N.P.)
| | - Hilary Ranson
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Graham Small
- Innovative Vector Control Consortium (IVCC), Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK; (C.F.); (G.S.)
| | - Joseph Wagman
- Malaria and Neglected Tropical Diseases Program, PATH, Washington, DC 20001, USA;
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK; (J.H.); (N.L.); (H.R.); (D.W.)
| | - Sarah Zohdy
- Division of Parasitic Diseases and Malaria, Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA; (J.E.G.); (D.I.); (S.Z.)
- U.S. President’s Malaria Initiative (PMI), Centers for Disease Control (CDC) and Prevention, Atlanta, GA 30329, USA;
| | - Angus Spiers
- Innovation to Impact, Pembroke Place, Liverpool L3 5QA, UK;
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13
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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: 4] [Impact Index Per Article: 2.0] [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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14
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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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15
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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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16
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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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17
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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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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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19
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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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20
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Abílio AP, Obi E, Koenker H, Babalola S, Saifodine A, Zulliger R, Swamidoss I, Ponce de Leon G, Alfai E, Blaufuss S, Olapeju B, Harig H, Kilian A. Monitoring the durability of the long-lasting insecticidal nets MAGNet and Royal Sentry in three ecological zones of Mozambique. Malar J 2020; 19:209. [PMID: 32552819 PMCID: PMC7301518 DOI: 10.1186/s12936-020-03282-w] [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: 12/07/2019] [Accepted: 06/06/2020] [Indexed: 11/24/2022] Open
Abstract
Background Malaria prevention with long-lasting insecticidal nets (LLINs) has seen a tremendous scale-up in sub-Saharan Africa in the last decade. To sustain this success, it is important to understand how long LLINs remain in the households and continue to protect net users, which is termed durability. This information is needed to decide the appropriate timing of LLIN distribution and also to identify product(s) that may be underperforming relative to expectations. Following guidance from the U.S. President’s Malaria Initiative, durability monitoring of polyethylene 150-denier LLIN (Royal Sentry® and MAGNet®) distributed during a 2017 mass campaign in Mozambique was implemented in three ecologically different sites: Inhambane, Tete, and Nampula. Methods This was a prospective cohort study in which representative samples of households from each district were recruited at baseline, 1 to 6 months after the mass campaign. All campaign LLINs in these households were labelled and followed up over a period of 36 months. The primary outcome was the “proportion of LLINs 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 subsamples of campaign LLINs. Results A total of 998 households (98% of target) and 1998 campaign LLIN (85% of target) were included in the study. Definite outcomes could be determined for 80% of the cohort LLIN in Inhambane, 45% in Tete, and 72% in Nampula. The highest all-cause attrition was seen in Nampula with 74% followed by Inhambane at 56% and Tete at 50%. Overall, only 2% of campaign LLINs were used for other purposes. Estimated survival in serviceable condition of campaign LLINs after 36 months was 57% in Inhambane, 43% in Tete, and 33% in Nampula, corresponding to median survival of 3.0, 2.8, and 2.4 years, respectively. Factors that were associated with better survival were exposure to social and behavioural change communication, a positive net care attitude, and folding up the net during the day. Larger household size negatively impacted survival. Insecticidal performance was optimal up to 24 months follow-up, but declined at 36 months when only 3% of samples showed optimal effectiveness in Inhambane, 11% in Tete and 29% in Nampula. However, 96% of LLIN still had minimal effectiveness at 36 months. Conclusions Differences in median survival could be attributed at least in part to household environment and net care and repair behaviours. This means that in two of the three sites the assumption of a three-year cycle of campaign distributions holds, while in the Nampula site either continuous distribution channels could be expanded or more intense or targeted social and behaviour change activities to encourage net care and retention could be considered.
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Affiliation(s)
| | - Emmanuel Obi
- PMI VectorWorks Project, Tropical Health LLP, Abuja, Nigeria
| | - 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
| | - Abuchahama Saifodine
- U.S. President's Malaria Initiative, U.S. Agency for International Development, Maputo, Mozambique
| | - Rose Zulliger
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Maputo, Mozambique
| | - Isabel Swamidoss
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Gabriel Ponce de Leon
- U.S. President's Malaria Initiative, Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Eunice Alfai
- National Malaria Control Programme, Maputo, Mozambique
| | - 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
| | - Hunter Harig
- 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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21
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Sahu SS, Keshaowar AV, Thankachy S, Panigrahi DK, Acharya P, Balakrishnan V, Kumar A. Evaluation of bio-efficacy and durability of long-lasting insecticidal nets distributed by malaria elimination programme in Eastern India. Malar J 2020; 19:186. [PMID: 32448316 PMCID: PMC7247230 DOI: 10.1186/s12936-020-03260-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 05/15/2020] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Long-lasting insecticidal nets (LLINs) are the most favoured vector control tools worldwide. Timely monitoring and evaluation of LLINs is important to sustain the impact of this promising vector control method and for replacement of worn-out and those rendered ineffective. During the mid-2017, LLINs were distributed by the National Vector Borne Disease Control Programme (NVBDCP) in high malaria endemic districts of the eastern coastal state of Odisha. The study was carried out to assess the field performance of the LLINs post 30 months of distribution in Koraput district of Odisha state. METHODS A total of 130 households were randomly selected from three villages of Laxmipur CHC in Koraput district, Odisha, India; one each from hilltop, foothill and plain terrain. The net users were interviewed to elicit information on usage, washing practices, physical integrity, bio-efficacy and survivorship of LLINs to confirm the claimed three-year life of the LLINs. RESULTS 74.8% of the LLINs were physically present after 30 months of distribution. The numbers (%) of LLINs used previous night varied from 30 to 61% between study villages. 74% respondents were using the LLINs throughout the year and 26% only seasonally. Of the total, 85% of the nets were reported to be washed and 95% nets were dried under shade as recommended. Altogether, 58% of the surveyed nets were found torn with holes. Of these, 74 (57%) nets were in good condition, 10 (8%) nets were in serviceable and 45 (35%) nets were badly torn and needed replacement. A total of 45 (93.75%), 68 (80%) and 71 (63.8%) LLINs were physically present in hilltop, foothill and plain villages, respectively. The LLINs did meet the efficacy criteria, given the 100% mortality to the exposed Anopheles jeyporiensis mosquitoes post 30 months distribution. CONCLUSIONS The findings of this study were communicated to the programme officials of the state and LLINs were replenished soon after 31st month post-distribution of LLINs.
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Affiliation(s)
- Sudhansu Sekhar Sahu
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India.
| | - Amol Vasantrao Keshaowar
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
| | - Sonia Thankachy
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
| | - Dilip Kumar Panigrahi
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
| | - Premalata Acharya
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
| | - Vijayakumar Balakrishnan
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
| | - Ashwani Kumar
- Indian Council of Medical Research-Vector Control Research Centre, Medical Complex, Indira Nagar, Puducherry, 605006, India
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Ghimire P, Rijal KR, Adhikari N, Thakur GD, Marasini B, Thapa Shrestha U, Banjara MR, Pant SK, Adhikari B, Dumre SP, Singh N, Pigeon O, Chareonviriyaphap T, Chavez I, Ortega L, Hii J. The durability of long-lasting insecticidal nets distributed to the households between 2009 and 2013 in Nepal. Trop Med Health 2020; 48:36. [PMID: 32476984 PMCID: PMC7236445 DOI: 10.1186/s41182-020-00223-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 05/05/2020] [Indexed: 11/10/2022] Open
Abstract
Background Understanding and improving the durability of long-lasting insecticidal nets (LLINs) in the field are critical for planning future implementation strategies including behavioral change for care and maintenance. LLIN distribution at high coverage is considered to be one of the adjunctive transmission reduction strategies in Nepal's Malaria Strategic Plan 2014-2025. The main objective of this study was to assess the durability through assessment of community usage, physical integrity, residual bio-efficacy, and chemical retention in LLINs: Interceptor®, Yorkool®, and PermaNet ®2.0 which were used in Nepal during 2009 through 2013. Methods Assessments were conducted on random samples (n = 440) of LLINs from the eleven districts representing four ecological zones: Terai plain region (Kailali and Kanchanpur districts), outer Terai fluvial ecosystem (Surkhet, Dang, and Rupandhei districts), inner Terai forest ecosystem (Mahhothari, Dhanusa, and Illam districts), and Hills and river valley (Kavrepalanchock and Sindhupalchok districts). For each LLIN, fabric integrity in terms of proportionate hole index (pHI) and residual bio-efficacy were assessed. However, for chemical retention, a representative sample of 44 nets (15 Yorkool®, 10 Permanet®2.0, and 19 Interceptor®) was evaluated. Data were analyzed using descriptive statistics stratified by LLINs brand, districts, and duration of exposure. Results On average, duration of use of LLINs was shortest for the Yorkool® samples, followed by PermaNet® 2.0 and Interceptor® with median ages of 8.9 (IQR = 0.4), 23.8 (IQR = 3.2), and 50.1 (IQR = 3.2) months, respectively. Over 80% of field distributed Yorkool® and PermaNet® 2.0 nets were in good condition (pHI< 25) compared to Interceptor® (66%). Bio-efficacy analysis showed that average mortality rates of Interceptor and Yorkool were below World Health Organization (WHO) optimal effectiveness of ≥ 80% compared to 2-year-old PermaNet 2.0 which attained 80%. Chemical retention analysis was consistent with bio-efficacy results. Conclusion This study shows that distribution of LLINs is effective for malaria control; however, serviceable life of LLINs should be considered in terms of waning residual bio-efficacy that warrants replacement. As an adjunctive malaria control tool, National Malaria Control Program of Nepal can benefit by renewing the distribution of LLINs in an appropriate time frame in addition to utilizing durable and effective LLINs.
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Affiliation(s)
- Prakash Ghimire
- 1Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal.,World Health Organization Country Office for Nepal, Pulchowk, Lalitpur, Nepal
| | - Komal Raj Rijal
- 1Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Nabaraj Adhikari
- 1Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Garib Das Thakur
- 3Epidemiology and Disease Control Division, Department of Health Services, Ministry of Health and Population, Kathmandu, Nepal
| | - Baburam Marasini
- 3Epidemiology and Disease Control Division, Department of Health Services, Ministry of Health and Population, Kathmandu, Nepal
| | | | - Megha Raj Banjara
- 1Central Department of Microbiology, Tribhuvan University, Kathmandu, Nepal
| | - Shishir Kumar Pant
- 4VectorBorne Disease Research and Training Center, Ministry of Health and Population, Hetauda, Nepal
| | - Bipin Adhikari
- 5Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Shyam Prakash Dumre
- 6Department of Immunogenetics, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan
| | - Nihal Singh
- World Health Organization Country Office for Nepal, Pulchowk, Lalitpur, Nepal
| | - Olivier Pigeon
- 7Agriculture and Natural Environment Department, Plant Protection Products and Biocides Physico-chemistry and Residues Unit, Walloon Agricultural Research Centre (CRA-W), Carson Building, Rue du Bordia, 11, B-5030 Gembloux, Belgium
| | | | - Irwin Chavez
- 9Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400 Thailand
| | - Leonard Ortega
- 10South-East Asia Regional Office, World Health Organization, New Delhi, India.,11Global Malaria Programme World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
| | - Jeffrey Hii
- 12Malaria Consortium, Faculty of Tropical Medicine, Mahidol University, 420/6 Rajvithi Road, Bangkok, 10400 Thailand.,13College of Public Health, Medical & Veterinary Sciences, James Cook University, Townville, QLD 4811 Australia
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Andrianjafy TM, Ramanandraibe VV, Andrianarijaona ET, Ramarosandratana NH, Ravaomanarivo LH, Mavingui P, Lemaire M. Field assessment of 4-hydroxycoumarin as an attractant for anthropophilic Anopheles spp. vectors of malaria in Madagascar. Sci Rep 2020; 10:3048. [PMID: 32080255 PMCID: PMC7033182 DOI: 10.1038/s41598-020-59822-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 01/16/2020] [Indexed: 02/03/2023] Open
Abstract
Mosquito-borne diseases like malaria are a major public health problem in tropical countries, such as Madagascar. Female Anopheles mosquito vectors the human malaria parasites (Plasmodium spp.) and is important indicator in malaria surveillance activities. Among the various means of vector control in Madagascar, the use of attractants for mass trapping of target species could be an alternative to insecticides. The aim of this study is to evaluate whether 4-hydroxycoumarin can be used as an attractant for anthropophilic Anopheles spp. vectors of malaria. For this, a field study was conducted using CDC light traps in the village of Ambohidray, Madagascar. 16 days of trapping was conducted and four replicates nights were performed for each product tested. 4-hydroxycoumarin, octenol and two types of blend of these products were tested. The results showed that 4-hydroxycoumarin (2 mg) have a significant attractive effect on Anopheles spp. and significant selectivity towards Anopheles gambiae s.l, and Anopheles mascarensis which are both significant malaria vectors in Madagascar. A synergy of 4-hydroxycoumarin with octenol was found to attract these mosquito vectors. A significant decrease in vector populations was observed during this experiment. These results suggest that 4-hydroxycoumarin could be useful for malaria surveillance and the control of vector populations.
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Affiliation(s)
- Tovo Mbolatiana Andrianjafy
- International Associated Laboratory, University of Antananarivo-Lyon 1, PO Box 906, Antananarivo, Madagascar
- Department of Entomology, University of Antananarivo, PO Box 906, Antananarivo, Madagascar
| | | | | | | | | | - Patrick Mavingui
- International Associated Laboratory, University of Antananarivo-Lyon 1, PO Box 906, Antananarivo, Madagascar
- University of La Réunion, UMR PIMIT, INSERM 1187, CNRS 9192, IRD 249, Plateforme CYROI, 2 Rue Maxime Rivière, Sainte Clotilde, La Réunion, France
| | - Marc Lemaire
- International Associated Laboratory, University of Antananarivo-Lyon 1, PO Box 906, Antananarivo, Madagascar.
- ICBMS, CNRS, UMR 5246, University of Claude Bernard Lyon, 1 rue Victor Grignard, Bâtiment Lederer, 69622, Villeurbanne Cedex, France.
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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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Santos EM, Coalson JE, Jacobs ET, Klimentidis YC, Munga S, Agawo M, Anderson E, Stroupe N, Ernst KC. Bed net care practices and associated factors in western Kenya. Malar J 2019; 18:274. [PMID: 31412865 PMCID: PMC6694604 DOI: 10.1186/s12936-019-2908-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 08/08/2019] [Indexed: 11/22/2022] Open
Abstract
Background Insecticide-treated nets (ITNs) and long-lasting insecticidal nets (LLINs) are effective for malaria prevention and are designed to provide nearly 5 years of mosquito protection. However, many ITNs and LLINs become damaged and ineffective for mosquito bite prevention within 1 to 2 years in field conditions. Non-adherence to recommended bed net care and repair practices may partially explain this shortened net longevity. Methods Using data from a cross-sectional study, a net care adherence score was developed and adherence to net care practices described from two regions of western Kenya. Relationships between attitudes and environmental factors that influence net longevity were measured with adherence to bed net care practices. Results While overall care practices are highly adherent particularly in the highlands, practices related to daily storage, washing frequency, and drying location need improvement in the lowlands. Seventy-seven percent of nets in the lowlands were washed < 3 months prior to the survey compared to 23% of nets in the highlands. More nets were dried in the sun in the lowlands (32% of nets) compared to the highlands (4% of nets). Different elements of care are influenced by various malaria attitudes and environmental factors, highlighting the complexity of factors associated with net care. For example, households that learned about net care from community events, that share a sleeping structure with animals, and that have nets used by adult males tend to adhere to washing frequency recommendations. Conclusions In western Kenya, many nets are cared for in accordance to recommended practices, particularly in the highlands sites. In the lowlands, demonstrating methods at community events to tie nets up during the day coupled with messaging to emphasize infrequent washing and drying nets in the shade may be an appropriate intervention. As illustrated by differences between the highlands and lowlands sites in the present study, should interventions to improve adherence to bed net care practices be necessary, they should be context-specific. Electronic supplementary material The online version of this article (10.1186/s12936-019-2908-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ellen M Santos
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA.
| | - Jenna E Coalson
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
| | - Elizabeth T Jacobs
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
| | - Yann C Klimentidis
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
| | - Stephen Munga
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu, Nyanza, 40100, Kenya
| | - Maurice Agawo
- Centre for Global Health Research, Kenya Medical Research Institute, PO Box 1578, Kisumu, Nyanza, 40100, Kenya
| | - Elizabeth Anderson
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
| | - Nancy Stroupe
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
| | - Kacey C Ernst
- Mel and Enid Zuckerman College of Public Health, University of Arizona, 1295N Martin Ave, Tucson, AZ, 85724, USA
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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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Massue DJ, Lorenz LM, Moore JD, Ntabaliba WS, Ackerman S, Mboma ZM, Kisinza WN, Mbuba E, Mmbaga S, Bradley J, Overgaard HJ, Moore SJ. Comparing the new Ifakara Ambient Chamber Test with WHO cone and tunnel tests for bioefficacy and non-inferiority testing of insecticide-treated nets. Malar J 2019; 18:153. [PMID: 31039788 PMCID: PMC6492396 DOI: 10.1186/s12936-019-2741-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/21/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Insecticide-treated net (ITN) durability, measured through physical integrity and bioefficacy, must be accurately assessed in order to plan the timely replacement of worn out nets and guide procurement of longer-lasting, cost-effective nets. World Health Organization (WHO) guidance advises that new intervention class ITNs be assessed 3 years after distribution, in experimental huts. In order to obtain information on whole-net efficacy cost-effectively and with adequate replication, a new bioassay, the Ifakara Ambient Chamber Test (I-ACT), a semi-field whole net assay baited with human host, was compared to established WHO durability testing methods. METHODS Two experiments were conducted using pyrethroid-susceptible female adult Anopheles gambiae sensu stricto comparing bioefficacy of Olyset®, PermaNet® 2.0 and NetProtect® evaluated by I-ACT and WHO cone and tunnel tests. In total, 432 nets (144/brand) were evaluated using I-ACT and cone test. Olyset® nets (132/144) that did not meet the WHO cone test threshold criteria (≥ 80% mortality or ≥ 95% knockdown) were evaluated using tunnel tests with threshold criteria of ≥ 80% mortality or ≥ 90% feeding inhibition for WHO tunnel and I-ACT. Pass rate of nets tested by WHO combined standard WHO bioassays (cone/tunnel tests) was compared to pass in I-ACT only by net brand and time after distribution. RESULTS Overall, more nets passed WHO threshold criteria when tested with I-ACT than with standard WHO bioassays 92% vs 69%, (OR: 4.1, 95% CI 3.5-4.7, p < 0.0001). The proportion of Olyset® nets that passed differed if WHO 2005 or WHO 2013 LN testing guidelines were followed: 77% vs 71%, respectively. Based on I-ACT results, PermaNet® 2.0 and NetProtect® demonstrated superior mortality and non-inferior feeding inhibition to Olyset® over 3 years of field use in Tanzania. CONCLUSION Ifakara Ambient Chamber Test may have use for durability studies and non-inferiority testing of new ITN products. It measures composite bioefficacy and physical integrity with both mortality and feeding inhibition endpoints, using fewer mosquitoes than standard WHO bioassays (cone and tunnel tests). The I-ACT is a high-throughput assay to evaluate ITN products that work through either contact toxicity or feeding inhibition. I-ACT allows mosquitoes to interact with a host sleeping underneath a net as encountered in the field, without risk to human participants.
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Affiliation(s)
- Dennis J Massue
- 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.
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania.
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania.
| | - Lena M Lorenz
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Jason D Moore
- 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
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | | | - Samuel Ackerman
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Zawadi M Mboma
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
- Department of Disease Control, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - William N Kisinza
- National Institute for Medical Research, Amani Research Centre, P. O. Box 81, Muheza, Tanga, Tanzania
| | - Emmanuel Mbuba
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - Selemani Mmbaga
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
| | - John Bradley
- MRC Tropical Epidemiology Group, London School of Hygiene and Tropical Medicine, London, WC1E 7HT, UK
| | - Hans J Overgaard
- Faculty of Science and Technology, Norwegian University of Life Sciences, Ås, Norway
| | - Sarah J Moore
- 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
- Ifakara Health Institute, P. O. Box 74, Bagamoyo, Pwani, Tanzania
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Testing bio-efficacy of insecticide-treated nets with fewer mosquitoes for enhanced malaria control. Sci Rep 2018; 8:16769. [PMID: 30425283 PMCID: PMC6233220 DOI: 10.1038/s41598-018-34979-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 10/07/2018] [Indexed: 11/29/2022] Open
Abstract
Malaria control programs implementing Long-Lasting Insecticidal Nets (LLINs) are encouraged to conduct field monitoring of nets’ survival, fabric integrity and insecticidal bio-efficacy. The reference method for testing the insecticide activity of LLINs needs 100 two-to-five-day-old female mosquitoes per net, which is highly resource-intensive. We aimed at identifying an alternative protocol, using fewer mosquitos, while ensuring a precision in the main indicator of ±5 percentage points (pp). We compared different laboratory methods against the probability of the LLIN to fail the test as determined by a hierarchical Bayesian model. When using 50 mosquitoes per LLIN and considering mortality only instead of mortality or knock-down as validity criteria, the average error in the measure of the proportion of nets considered as valid was 0.40 pp. The 95% confidence interval of this value never exceed 5 pp when the number of LLIN tested was ≥40. This method slightly outperforms the current recommendations. As a conclusion, testing the bio-efficacy of LLINs with half as many mosquitoes provides a valid evaluation of the proportion of valid LLINs. This approach could increase entomology labs’ testing capacity and decrease costs, with no impact in the decision process for public health purposes.
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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: 35] [Impact Index Per Article: 5.8] [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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30
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Girond F, Madec Y, Kesteman T, Randrianarivelojosia M, Randremanana R, Randriamampionona L, Randrianasolo L, Ratsitorahina M, Herbreteau V, Hedje J, Rogier C, Piola P. Evaluating Effectiveness of Mass and Continuous Long-lasting Insecticidal Net Distributions Over Time in Madagascar: A Sentinel Surveillance Based Epidemiological Study. EClinicalMedicine 2018; 1:62-69. [PMID: 30294720 PMCID: PMC6169794 DOI: 10.1016/j.eclinm.2018.07.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND The reduction of global malaria burden over the past 15 years is much attributed to the expansion of mass distribution campaigns (MDCs) of long-lasting insecticidal nets (LLIN). In Madagascar, two LUN MDCs were implemented and one district also benefited from a community-based continuous distribution (CB-CD). Malaria incidence dropped but eventually rebounded after a decade. METHODS Data from a sentinel surveillance network over the 2009-2015 period was analyzed. Alerts were defined as w eekly number o f malaria cases exceeding the 90th percentile value for three consecutive weeks. Statistical analyses assessed the temporal relationship between LLIN MDCs and (i) number of malaria cases and (ii) malaria alerts detected, and (iii) the effect of a combination of MDCs and a CB-CD in Toamasina District. FINDINGS Analyses showed an increase of 13.6 points and 21.4 points in the percentile value of weekly malaria cases during the second and the third year following the MDC of LLINs respectively. The percentage of alert-free sentinel sites was 98.2% during the first year after LLIN MDC, 56.7% during the second year and 31.5% during the third year. The number of weekly malaria cases decreased by 14% during the CB-CD in Toamasina District. In contrast, sites without continuous distribution had a 12% increase of malaria cases. INTERPRETATION These findings support the malaria-preventive effectiveness of MDCs in Madagascar but highlight their limited duration when not followed by continuous distribution. The resulting policy implications are crucial to sustain reductions in malaria burden in high transmission settings.
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Affiliation(s)
- Florian Girond
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
- UMR 228 ESPACE-DEV (IRD, UAG, UM, UR), Station SEAS-OI, 40 avenue de Soweto, 97410 Saint Pierre, France
- Elimination 8 (E8), Windhoek, Namibia
- Corresponding author at: 175 CD 26, L'Entre-Deux 97414, Ile de la Réunion, France.
| | - Yoann Madec
- Emerging Diseases Epidemiology Unit, Institut Pasteur, 25-28, rue du Docteur Roux, 75015 Paris, France
| | - Thomas Kesteman
- Unité de Recherche sur le Paludisme, Institut Pasteur de Madagascar, BP 1274, Avaradoha, Antananarivo 101, Madagascar
- Fondation Mérieux, 17 rue Bourgelat, 69002 Lyon, France
| | | | - Rindra Randremanana
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
| | - Lea Randriamampionona
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
- Direction de Veille Sanitaire et de Surveillance Epidémiologique, Ministry of Health, Madagascar
| | - Laurence Randrianasolo
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
| | - Maherisoa Ratsitorahina
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
- Direction de Veille Sanitaire et de Surveillance Epidémiologique, Ministry of Health, Madagascar
| | - Vincent Herbreteau
- UMR 228 ESPACE-DEV (IRD, UAG, UM, UR), Station SEAS-OI, 40 avenue de Soweto, 97410 Saint Pierre, France
| | - Judith Hedje
- Malaria Branch, Division of Parasitic Diseases and Malaria, Center for Global Health, US Centers for Disease Control and Prevention, Atlanta, GA, USA
- U.S. President's Malaria Initiative, Antananarivo 101, Madagascar
| | - Christophe Rogier
- Institut Pasteur de Madagascar, Antananarivo, Madagascar
- Unité de recherche sur les maladies infectieuses et tropicales émergentes (URMITE) - UMR 6236, 27 boulevard Jean Moulin, 13385 Marseille Cedex 05, France
- Institute for Biomedical Research of the French Armed Forces (IRBA), BP 73, 91223 Brétigny Sur Orge Cedex, France
| | - Patrice Piola
- Epidemiology Unit, Institut Pasteur de Madagascar, BP 1274 Avaradoha, Antananarivo 101, Madagascar
- Epidemiology and Public Health Unit, Institut Pasteur du Cambodge, Phnom Penh
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31
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Kang SY, Battle KE, Gibson HS, Ratsimbasoa A, Randrianarivelojosia M, Ramboarina S, Zimmerman PA, Weiss DJ, Cameron E, Gething PW, Howes RE. Spatio-temporal mapping of Madagascar's Malaria Indicator Survey results to assess Plasmodium falciparum endemicity trends between 2011 and 2016. BMC Med 2018; 16:71. [PMID: 29788968 PMCID: PMC5964908 DOI: 10.1186/s12916-018-1060-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 04/24/2018] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND Reliable measures of disease burden over time are necessary to evaluate the impact of interventions and assess sub-national trends in the distribution of infection. Three Malaria Indicator Surveys (MISs) have been conducted in Madagascar since 2011. They provide a valuable resource to assess changes in burden that is complementary to the country's routine case reporting system. METHODS A Bayesian geostatistical spatio-temporal model was developed in an integrated nested Laplace approximation framework to map the prevalence of Plasmodium falciparum malaria infection among children from 6 to 59 months in age across Madagascar for 2011, 2013 and 2016 based on the MIS datasets. The model was informed by a suite of environmental and socio-demographic covariates known to influence infection prevalence. Spatio-temporal trends were quantified across the country. RESULTS Despite a relatively small decrease between 2013 and 2016, the prevalence of malaria infection has increased substantially in all areas of Madagascar since 2011. In 2011, almost half (42.3%) of the country's population lived in areas of very low malaria risk (<1% parasite prevalence), but by 2016, this had dropped to only 26.7% of the population. Meanwhile, the population in high transmission areas (prevalence >20%) increased from only 2.2% in 2011 to 9.2% in 2016. A comparison of the model-based estimates with the raw MIS results indicates there was an underestimation of the situation in 2016, since the raw figures likely associated with survey timings were delayed until after the peak transmission season. CONCLUSIONS Malaria remains an important health problem in Madagascar. The monthly and annual prevalence maps developed here provide a way to evaluate the magnitude of change over time, taking into account variability in survey input data. These methods can contribute to monitoring sub-national trends of malaria prevalence in Madagascar as the country aims for geographically progressive elimination.
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Affiliation(s)
- Su Yun Kang
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Katherine E Battle
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Harry S Gibson
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Arsène Ratsimbasoa
- National Malaria Control Programme, Ministry of Health, Antananarivo, Madagascar.,University of Antananarivo, Antananarivo, Madagascar
| | - Milijaona Randrianarivelojosia
- Institut Pasteur de Madagascar, Antananarivo, Madagascar.,Faculté des Sciences, Université de Toliara, Toliara, Madagascar
| | - Stéphanie Ramboarina
- National Malaria Control Programme, Ministry of Health, Antananarivo, Madagascar.,University of Antananarivo, Antananarivo, Madagascar.,Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Peter A Zimmerman
- Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA
| | - Daniel J Weiss
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Ewan Cameron
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Peter W Gething
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Rosalind E Howes
- Malaria Atlas Project, Oxford Big Data Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK. .,Center for Global Health and Diseases, Case Western Reserve University, Cleveland, OH, USA.
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