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. 2005 Nov 3:4:52.
doi: 10.1186/1475-2875-4-52.

Evaluation of KO-Tab 1-2-3: a wash-resistant 'dip-it-yourself' insecticide formulation for long-lasting treatment of mosquito nets

Alison Yates  1 , Raphael N'Guessan, Harparkash Kaur, Martin Akogbéto, Mark Rowland
Affiliations

Evaluation of KO-Tab 1-2-3: a wash-resistant 'dip-it-yourself' insecticide formulation for long-lasting treatment of mosquito nets

Alison Yates et al. Malar J. .

Abstract

Introduction: Insecticide-treated nets (ITN) are an important method of preventing malaria. To remain effective, they need to be re-treated with pyrethroid insecticide at approximately yearly intervals. Systems for re-treating nets in Africa are limited, and the vast majority of nets in use have never been treated or were treated only once. Bayer Environmental Science (BES) has developed a long-lasting formulation 'KO-Tab 1-2-3' which can be applied to the net post-manufacture, under field conditions, and renders the insecticide wash-resistant.

Methods: The performance of polyester nets treated with three kinds of BES long-lasting formulations, a conventional ITN (treated with standard KO-Tab) and PermaNet 2.0 were evaluated after washing samples of treated netting up to 30 times using standard WHO procedures. Performance was measured using 'three-minute exposure' and 'median time to knockdown' bioassay tests and by measuring the levels of deltamethrin using high-pressure liquid chromatography.

Results: The conventional ITN was largely stripped of deltamethrin within 5-10 washes and insecticidal efficacy in bioassay declined to suboptimal levels. With PermaNet and KO-Tab 1-2-3 the loss of deltamethrin was much slower: insecticide content halved within 20 washes and there was no loss of biological efficacy in three-minute exposure bioassays in WHO cylinders even after 30 washes. After 30 washes there remained on the netting 16% (4.4 mg/m2) of the loading dose of KO-Tab 1-2-3 and 28% (18.8 mg/m2) of the loading dose of PermaNet.

Conclusion: KO-Tab 1-2-3 was confirmed to be a long-lasting insecticide formulation. This finding raises the prospect of conventional polyester nets being converted into long-lasting insecticidal nets through simple dipping in the community or at home. This single development, if widely adopted, could transform the malaria control landscape in Africa and have a major impact on malaria.

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Figures

Figure 1
Figure 1
Mean (± CI) dosage of deltamethrin (mg/m2) before and after washing as measured using high-pressure liquid chromatography.
Figure 2
Figure 2
Three-minute exposure bioassay tests: proportion dead after 24 h. Seven replicate tests (70 mosquitoes exposed) were carried out on each formulation and wash interval.
Figure 4
Figure 4
The relationship between median time to knockdown and dosage of deltamethrin.
Figure 5
Figure 5
The relationship between % mortality (from three minutes bioassays) and dosage of deltamethrin.
Figure 3
Figure 3
Median time to knockdown tests: means and confidence intervals. Nine replicate tests were carried out on each formulation and wash interval.
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References

    1. Lengeler C. Insecticide-treated bednets and curtains for preventing malaria. Cochrane Database Syst Rev. 2004:CD000363. - PubMed
    1. Itoh T, Okuno T. Evaluation of the polyethylene net incorporated with permethrin during manufacture of thread on efficacy against Aedes aegypti (Linnaeus) Med Entomol Zool. 1996;47:171–174.
    1. N'Guessan R, Darriet F, Doannio JMC, Chandre F, Carnevale P. Olyset net efficacy against pyrethroid-resistant Anopheles and Culex after 3 years' field use in Côte D'Ivoire. Med Vet Entomol. 2001;15:97–104. doi: 10.1046/j.1365-2915.2001.00284.x. - DOI - PubMed
    1. Muller O, Ido K, Traore C. Evaluation of a prototype long-lasting insecticide-treated mosquito net under field conditions in rural Burkina Faso. Trans R Soc Trop Med Hyg. 2002;96:483–484. doi: 10.1016/S0035-9203(02)90411-6. - DOI - PubMed
    1. Kroeger A, Skovmand O, Phan QC, Boewono DT. Combined field and laboratory evaluation of a long-term impregnated bednet, PermaNet®. Trans R Soc Trop Med Hyg. 2004;98:152–155. doi: 10.1016/S0035-9203(03)00038-5. - DOI - PubMed

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