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Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity

Briet, Olivier and Koenker, Hannah and Norris, Laura and Wiegand, Ryan and Vanden Eng, Jodi and Thackeray, Alex and Williamson, John and Gimnig, John E. and Fortes, Filomeno and Akogbeto, Martin and Yadouleton, Anges W. and Ombok, Maurice and Bayoh, M. Nabie and Mzilahowa, Themba and Abílio, Ana Paula and Mabunda, Samuel and Cuamba, Nelson and Diouf, Elhadji and Konaté, Lassana and Hamainza, Busiku and Katebe-Sakala, Cecilia and Ponce de León, Gabriel and Asamoa, Kwame and Wolkon, Adam and Smith, Stephen C. and Swamidoss, Isabel and Green, Mike and Gueye, Salam and Mihigo, Jules and Morgan, Juliette and Dotson, Ellen and Craig, Allen S. and Tan, Kathrine R. and Wirtz, Robert A. and Smith, Tom. (2020) Attrition, physical integrity and insecticidal activity of long-lasting insecticidal nets in sub-Saharan Africa and modelling of their impact on vectorial capacity. Malaria journal, 19. p. 310.

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Abstract

Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear.; Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels.; There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss.; There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.
Faculties and Departments:09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH)
09 Associated Institutions > Swiss Tropical and Public Health Institute (Swiss TPH) > Former Units within Swiss TPH > Infectious Disease Modelling > Epidemiology and Transmission Dynamics (Smith)
UniBasel Contributors:Briët, Olivier and Smith, Thomas
Item Type:Article, refereed
Article Subtype:Research Article
ISSN:1475-2875
Note:Publication type according to Uni Basel Research Database: Journal article
Language:English
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Last Modified:16 Dec 2022 11:35
Deposited On:16 Dec 2022 11:35

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