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Wash resistance of insecticide-treated materials

Gonzalez, Jose Ordenez, Kroeger, Axel, Avina, Ana Isabel and Pabon, E. (2002) 'Wash resistance of insecticide-treated materials'. Transactions of the Royal Society of Tropical Medicine and Hygiene, Vol 96, Issue 4, pp. 370-375.

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The effectiveness of insecticide-treated materials (ITMs) for malaria control is reduced by washing them. This research in Colombia and Bolivia investigated the resistance of different insecticide formulations and, in particular, a commercially available impregnated bednet (PermaNet((R))) which provides chemical protection for the insecticide. The fabrics studied were all polyester; the pyrethroids used for impregnation were deltamethrin (tablet and suspension concentrate both at 25 mg/m(2) target dose), lambdacyhalothrin (capsule suspension at 15 mg/m(2); laboratory study only), alphacypermethrin (suspension concentrate at 40 mg/m(2)) and, in the case of PermaNet, deltamethrin (55 mg/m(2)). The indicator of wash resistance was Anopheles spp. mortality (using the bioassay cone method) before and after different numbers and intensities of washing. When the fabrics were washed under controlled conditions, gently with water and a bar of soap, the wash resistance of all formulations was good (100% Anopheles mortality after 3 washes). However, when the impregnated nets were soaked for 30-60 min and washed with soap powder and tap water by local women in the usual way, the mortality after 4 washes declined considerably (43(.)5% and 41(.)3% for deltamethrin tablets and liquid respectively when washing every second day). Alphacypermethrin showed slightly better results after 3 washes every 7th day compared to deltamethrin tablets (63(.)8% and 43(.)3% mortality, respectively). The wash resistance offered by PermaNet was much better and longer lasting: Anopheles mortality after 4 washes was 92(.)6%, after 10 washes 83(.)7% and after 20 washes 87(.)1%. The limitations of commercially available wash-resistant nets are, however, their limited accessibility and the difficulty of replacing all existing bednets with a new product.

Item Type: Article
Subjects: WA Public Health > WA 30 Socioeconomic factors in public health (General)
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 750 Malaria
WC Communicable Diseases > Tropical and Parasitic Diseases > WC 765 Prevention and control
Faculty: Department: Groups (2002 - 2012) > Disease Control Strategy Group
Digital Object Identifer (DOI):
Depositing User: Users 476 not found.
Date Deposited: 13 Dec 2012 16:58
Last Modified: 06 Feb 2018 13:05


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