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Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the first line choice for malaria vector control in sub-Saharan Africa, with most countries adopting universal coverage campaigns. However, there is only limited information on LLIN durability under user conditions. Therefore, this study aimed t...

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Autores principales: Massue, Dennis J., Moore, Sarah J., Mageni, Zawadi D., Moore, Jason D., Bradley, John, Pigeon, Olivier, Maziba, Erasto J., Mandike, Renata, Kramer, Karen, Kisinza, William N., Overgaard, Hans J., Lorenz, Lena M.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797150/
https://www.ncbi.nlm.nih.gov/pubmed/26993981
http://dx.doi.org/10.1186/s12936-016-1225-6
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author Massue, Dennis J.
Moore, Sarah J.
Mageni, Zawadi D.
Moore, Jason D.
Bradley, John
Pigeon, Olivier
Maziba, Erasto J.
Mandike, Renata
Kramer, Karen
Kisinza, William N.
Overgaard, Hans J.
Lorenz, Lena M.
author_facet Massue, Dennis J.
Moore, Sarah J.
Mageni, Zawadi D.
Moore, Jason D.
Bradley, John
Pigeon, Olivier
Maziba, Erasto J.
Mandike, Renata
Kramer, Karen
Kisinza, William N.
Overgaard, Hans J.
Lorenz, Lena M.
author_sort Massue, Dennis J.
collection PubMed
description BACKGROUND: Long-lasting insecticidal nets (LLINs) are the first line choice for malaria vector control in sub-Saharan Africa, with most countries adopting universal coverage campaigns. However, there is only limited information on LLIN durability under user conditions. Therefore, this study aimed to assess the durability of Olyset(®) LLINs distributed during campaigns between 2009 and 2011 in Tanzania. METHODS: A retrospective field survey was conducted in eight districts in Tanzania mainland to assess the durability of Olyset campaign nets. Household questionnaires were used to assess attrition, i.e. net loss. All nets remaining in households were collected. A sub-sample of 198 Olyset campaign nets was examined for bio-efficacy against Anopheles gambiae s.s. mosquitoes, permethrin content and physical integrity following standard World Health Organization (WHO) methods. RESULTS: Of 6067 campaign nets reported to have been received between 2009 and 2011, 35 % (2145 nets) were no longer present. Most of those nets had been discarded (84 %) mainly because they were too torn (94 %). Of the 198 sub-sampled Olyset LLINs, 61 % were still in serviceable physical condition sufficient to provide personal protection while 39 % were in unserviceable physical condition according to WHO proportionate Hole Index (pHI). More than 96 % (116/120) of nets in serviceable condition passed WHO bioefficacy criteria while all nets in unserviceable condition passed WHO bioefficacy criteria. Overall mean permethrin content was 16.5 g/kg (95 % CI 16.2–16.9) with 78 % of the sub-sampled nets retaining recommended permethrin content regardless of their age or physical condition. Nets aged 4 years and above had a mean permethrin content of 14 g/kg (95 % CI 12.0–16.0). The only statistically significant predictor of reduced physical net integrity was rats in the house. CONCLUSIONS: Two-to-four years after a mass campaign, only 39 % of distributed nets remain both present and in serviceable physical condition, a functional survival considerably below WHO assumptions of 50 % survival of a ‘three-year’ net. However, the majority of nets still retained substantial levels of permethrin and could still be bio-chemically useful against mosquitoes if their holes were repaired, adding evidence to the value of net care and repair campaigns.
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spelling pubmed-47971502016-03-18 Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania Massue, Dennis J. Moore, Sarah J. Mageni, Zawadi D. Moore, Jason D. Bradley, John Pigeon, Olivier Maziba, Erasto J. Mandike, Renata Kramer, Karen Kisinza, William N. Overgaard, Hans J. Lorenz, Lena M. Malar J Research BACKGROUND: Long-lasting insecticidal nets (LLINs) are the first line choice for malaria vector control in sub-Saharan Africa, with most countries adopting universal coverage campaigns. However, there is only limited information on LLIN durability under user conditions. Therefore, this study aimed to assess the durability of Olyset(®) LLINs distributed during campaigns between 2009 and 2011 in Tanzania. METHODS: A retrospective field survey was conducted in eight districts in Tanzania mainland to assess the durability of Olyset campaign nets. Household questionnaires were used to assess attrition, i.e. net loss. All nets remaining in households were collected. A sub-sample of 198 Olyset campaign nets was examined for bio-efficacy against Anopheles gambiae s.s. mosquitoes, permethrin content and physical integrity following standard World Health Organization (WHO) methods. RESULTS: Of 6067 campaign nets reported to have been received between 2009 and 2011, 35 % (2145 nets) were no longer present. Most of those nets had been discarded (84 %) mainly because they were too torn (94 %). Of the 198 sub-sampled Olyset LLINs, 61 % were still in serviceable physical condition sufficient to provide personal protection while 39 % were in unserviceable physical condition according to WHO proportionate Hole Index (pHI). More than 96 % (116/120) of nets in serviceable condition passed WHO bioefficacy criteria while all nets in unserviceable condition passed WHO bioefficacy criteria. Overall mean permethrin content was 16.5 g/kg (95 % CI 16.2–16.9) with 78 % of the sub-sampled nets retaining recommended permethrin content regardless of their age or physical condition. Nets aged 4 years and above had a mean permethrin content of 14 g/kg (95 % CI 12.0–16.0). The only statistically significant predictor of reduced physical net integrity was rats in the house. CONCLUSIONS: Two-to-four years after a mass campaign, only 39 % of distributed nets remain both present and in serviceable physical condition, a functional survival considerably below WHO assumptions of 50 % survival of a ‘three-year’ net. However, the majority of nets still retained substantial levels of permethrin and could still be bio-chemically useful against mosquitoes if their holes were repaired, adding evidence to the value of net care and repair campaigns. BioMed Central 2016-03-18 /pmc/articles/PMC4797150/ /pubmed/26993981 http://dx.doi.org/10.1186/s12936-016-1225-6 Text en © Massue et al. 2016 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Massue, Dennis J.
Moore, Sarah J.
Mageni, Zawadi D.
Moore, Jason D.
Bradley, John
Pigeon, Olivier
Maziba, Erasto J.
Mandike, Renata
Kramer, Karen
Kisinza, William N.
Overgaard, Hans J.
Lorenz, Lena M.
Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title_full Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title_fullStr Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title_full_unstemmed Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title_short Durability of Olyset campaign nets distributed between 2009 and 2011 in eight districts of Tanzania
title_sort durability of olyset campaign nets distributed between 2009 and 2011 in eight districts of tanzania
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4797150/
https://www.ncbi.nlm.nih.gov/pubmed/26993981
http://dx.doi.org/10.1186/s12936-016-1225-6
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