Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance
Abstract Background Long-Lasting Insecticidal Nets (LLINs) are effective malaria prevention tools. However, information is limited about their durability and wash resistance in field circumstances, especially in seasonal transmission areas in South Asia. This study comprised a systematic examination...
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BMC
2025-04-01
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| Series: | Malaria Journal |
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| Online Access: | https://doi.org/10.1186/s12936-025-05346-1 |
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| author | Martijn Vink Mushtaq Ahmad Muhammad Farooq Sabawoon Mohammad Sami Nahzat Abdul Majeed Siddiqi Mohammad Naseem Najeebullah Alizoi Henk D. Schallig John Bradley Sarah Moore Maarten F. Schim van der Loeff |
| author_facet | Martijn Vink Mushtaq Ahmad Muhammad Farooq Sabawoon Mohammad Sami Nahzat Abdul Majeed Siddiqi Mohammad Naseem Najeebullah Alizoi Henk D. Schallig John Bradley Sarah Moore Maarten F. Schim van der Loeff |
| author_sort | Martijn Vink |
| collection | DOAJ |
| description | Abstract Background Long-Lasting Insecticidal Nets (LLINs) are effective malaria prevention tools. However, information is limited about their durability and wash resistance in field circumstances, especially in seasonal transmission areas in South Asia. This study comprised a systematic examination of usage, physical integrity and insecticidal activity of LLINs in households in Afghanistan, three years after distribution. Methods In 2014, 500 households in 5 malaria endemic Afghan provinces (Balkh, Herat, Khost, Kunduz and Nangarhar) that had received LLINs (PermaNet 2.0) three years earlier were randomly selected through cluster sampling. All household heads were interviewed about LLIN survivorship, usage and maintenance. One randomly selected LLIN from each household was rigorously inspected to calculate the proportionate Hole Index (pHI). Four location-specific pieces from 200 randomly selected LLINs (40 per province) underwent cone bioassay testing in the Jalalabad entomology laboratory, to measure mosquito knock-down after 60 min and 24-h mortality. The number and percentage of nets with ≥ 80% mosquito mortality was assessed. Five location-specific pieces from 34 randomly selected LLINs (5–8 per province) were tested for insecticidal content by High-Performance Liquid Chromatography (HPLC). Results Of the 1190 distributed LLINs, 1045 were still in the household at the time of the survey (survivorship 87.8%) and 1006 of those (96.3%) had been used every night in the past week. 9.1% of the LLINs were used by more than three people.. Physical integrity measurements indicated that 97.0% of the LLINs were in a serviceable condition (pHI 0–642), while 3.0% were ‘too torn’ (pHI > 642). Functional Net survival was 93.4% (95%CI 91.7–94.8%). However, only 28% of the LLINs met the WHOPES ≥ 80% mortality criterion. Washing of LLINs was associated with a significant reduction in mosquito mortality. Median deltamethrin concentration was 0.12 g/kg netting material (6.7% of the original concentration at production). Conclusions LLIN survivorship and functional net survival in this setting was excellent, while only a minority of LLINs retained sufficient insecticidal activity after three years of usage. This study underlines the need for evaluation of real-life LLIN durability in field circumstances. LLIN washing should be avoided, as it lowers insecticide content and LLIN efficacy. |
| format | Article |
| id | doaj-art-1dbcc3a9c5984b5ebdd328c27762ec7a |
| institution | OA Journals |
| issn | 1475-2875 |
| language | English |
| publishDate | 2025-04-01 |
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| series | Malaria Journal |
| spelling | doaj-art-1dbcc3a9c5984b5ebdd328c27762ec7a2025-08-20T02:24:26ZengBMCMalaria Journal1475-28752025-04-0124111310.1186/s12936-025-05346-1Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistanceMartijn Vink0Mushtaq Ahmad1Muhammad Farooq Sabawoon2Mohammad Sami Nahzat3Abdul Majeed Siddiqi4Mohammad Naseem5Najeebullah Alizoi6Henk D. Schallig7John Bradley8Sarah Moore9Maarten F. Schim van der Loeff10Health Net TPOHealthNet TPOHealthNet TPONational Malaria and Leishmaniasis Control Program (NMLCP) AfghanistanHealth Net TPOHealthNet TPOHealthNet TPODepartment of Medical Microbiology and Infection Prevention, Laboratory for Experimental Parasitology, Amsterdam University Medical Center, Location Academic Medical Center (AMC) at the University of AmsterdamMRC International Statistics and Epidemiology Group, London School of Hygiene and Tropical Medicine (LSHTM)Vector Control Product Testing Unit (VCPTU), Ifakara Health Institute (IHI)Public Health Service of Amsterdam (GGD)Abstract Background Long-Lasting Insecticidal Nets (LLINs) are effective malaria prevention tools. However, information is limited about their durability and wash resistance in field circumstances, especially in seasonal transmission areas in South Asia. This study comprised a systematic examination of usage, physical integrity and insecticidal activity of LLINs in households in Afghanistan, three years after distribution. Methods In 2014, 500 households in 5 malaria endemic Afghan provinces (Balkh, Herat, Khost, Kunduz and Nangarhar) that had received LLINs (PermaNet 2.0) three years earlier were randomly selected through cluster sampling. All household heads were interviewed about LLIN survivorship, usage and maintenance. One randomly selected LLIN from each household was rigorously inspected to calculate the proportionate Hole Index (pHI). Four location-specific pieces from 200 randomly selected LLINs (40 per province) underwent cone bioassay testing in the Jalalabad entomology laboratory, to measure mosquito knock-down after 60 min and 24-h mortality. The number and percentage of nets with ≥ 80% mosquito mortality was assessed. Five location-specific pieces from 34 randomly selected LLINs (5–8 per province) were tested for insecticidal content by High-Performance Liquid Chromatography (HPLC). Results Of the 1190 distributed LLINs, 1045 were still in the household at the time of the survey (survivorship 87.8%) and 1006 of those (96.3%) had been used every night in the past week. 9.1% of the LLINs were used by more than three people.. Physical integrity measurements indicated that 97.0% of the LLINs were in a serviceable condition (pHI 0–642), while 3.0% were ‘too torn’ (pHI > 642). Functional Net survival was 93.4% (95%CI 91.7–94.8%). However, only 28% of the LLINs met the WHOPES ≥ 80% mortality criterion. Washing of LLINs was associated with a significant reduction in mosquito mortality. Median deltamethrin concentration was 0.12 g/kg netting material (6.7% of the original concentration at production). Conclusions LLIN survivorship and functional net survival in this setting was excellent, while only a minority of LLINs retained sufficient insecticidal activity after three years of usage. This study underlines the need for evaluation of real-life LLIN durability in field circumstances. LLIN washing should be avoided, as it lowers insecticide content and LLIN efficacy.https://doi.org/10.1186/s12936-025-05346-1MalariaLong lasting insecticide treated netsBio-efficacyDurabilityAfghanistanLLIN |
| spellingShingle | Martijn Vink Mushtaq Ahmad Muhammad Farooq Sabawoon Mohammad Sami Nahzat Abdul Majeed Siddiqi Mohammad Naseem Najeebullah Alizoi Henk D. Schallig John Bradley Sarah Moore Maarten F. Schim van der Loeff Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance Malaria Journal Malaria Long lasting insecticide treated nets Bio-efficacy Durability Afghanistan LLIN |
| title | Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance |
| title_full | Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance |
| title_fullStr | Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance |
| title_full_unstemmed | Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance |
| title_short | Do long-lasting insecticidal nets retain their efficacy after three years of usage in Afghanistan? Findings from a study on survivorship, physical integrity, insecticidal activity and wash resistance |
| title_sort | do long lasting insecticidal nets retain their efficacy after three years of usage in afghanistan findings from a study on survivorship physical integrity insecticidal activity and wash resistance |
| topic | Malaria Long lasting insecticide treated nets Bio-efficacy Durability Afghanistan LLIN |
| url | https://doi.org/10.1186/s12936-025-05346-1 |
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