Autor(es): Faulde, Michael K; Albiez, Gunther; Nehring, Oliver

Resumo: A novel long-lasting repellent-treated net (LLRTN) has been designed by binding the skin repellents N,N-diethyl-m-toluamide (DEET), or IR3535, onto the fibres of bed net fabric using a new polymer-coating technique. The repellent toxicological effectiveness and residual activity of a factory-based repellent-impregnated fabric has been evaluated by laboratory testing against adult Aedes aegypti mosquitoes and nymphal Ixodes ricinus ticks. By using this repellent-embedding impregnation technique, concentrations exceeding 10 g/m2 could be achieved with one single polymer layer. Both DEET- and IR3535-impregnated fabrics revealed a dose-dependent insecticidal as well as acaricidal activity. One hundred percent knockdown times of DEET-treated bed nets ranged from 187.5-31.8 to 27.5-3.5 min against A. aegypti, and between 214-47 and 22.6-5 min against nymphal I. ricinus, linked to a DEET concentration of 1.08 and 10.58 g/m2, respectively. With IR3535, A. aegypti produced dose-dependent 100% knockdown times varying from 87.5-10.6 to 57.5-3.5 min and between 131.4-6.5 and 33.8-5 min against nymphal I. ricinus, respectively, linked to concentrations between 1.59 and 10.02 g/m2. One hundred percent repellency measured by complete landing and biting protection of impregnated fabric by using the arm-in-cage test could be achieved at DEET concentrations exceeding 3.7 to 3.9 g/m2, and for IR3535 concentrations over 10 g/m2. One hundred percent landing and biting protection could be preserved with DEET-treated fabrics for 29 weeks at an initial concentration of 4.66 g/m2, 54 weeks at 8.8 g/m2, 58 weeks at 9.96 g/m2 and 61 weeks at 10.48 g/m2 for DEET, and 23 weeks for IR3535-treated fabric at a concentration of 10.02 g/m2. Unlike repellent-treated fabric, a brand of a commercially available long-lasting insecticide-treated net tested containing 500 mg permethrin/m2 did not protect from mosquito bites. First results on bioactivity and long-lasting efficacy show that the new LLRTN technique is highly promising as a potential candidate for future malaria control strategies, especially in areas where pyrethroid resistance occurs.

Palavras-Chave: Landing statistics; Human diseases; Repellents; Malaria; Fabrics; Skin; Biting; DEET; Bites; Repellency; Permethrin; Pyrethroids; Nets; Aedes aegypti; Ixodidae; Ixodes ricinus

Imprenta: Parasitology Research, v. 106, n. 4, p. 957-965, 2010.

Descritores: Aedes aegypti - Repellent ; Aedes aegypti - Public health

Data de publicação: 2010

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