The durability of long-lasting insecticidal nets distributed to the households between 2009 and 2013 in Nepal

Ghimire, Prakash, Rijal, Komal Raj, Adhikari, Nabaraj, Thakur, Garib Das, Marasini, Baburam, Shrestha, Upendra Thapa, Banjara, Megha Raj, Pant, Shishir Kumar, Adhikari, Bipin, Dumre, Shyam Prakash, Singh, Nihal, Pigeon, Olivier, Chareonviriyaphap, Theeraphap, Chavez, Irwin, Ortega, Leonard, and Hii, Jeffrey (2020) The durability of long-lasting insecticidal nets distributed to the households between 2009 and 2013 in Nepal. Tropical Medicine and Health, 48. 36.

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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.

Item ID: 63500
Item Type: Article (Research - C1)
ISSN: 1349-4147
Keywords: Long-lasting insecticide treated nets, Durability, Malaria, Bio-efficacy, Chemical retention, Proportionate hole index, Nepal
Copyright Information: © The Author(s) 2020. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/
Funders: Global Fund to Fight AIDS, Tuberculosis and Malaria (GFFATM)
Date Deposited: 17 Jun 2020 07:50
FoR Codes: 42 HEALTH SCIENCES > 4206 Public health > 420699 Public health not elsewhere classified @ 100%
Downloads: Total: 38
Last 12 Months: 30
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