A randomized and controlled comparison of the wash-resistances and insecticidal efficacies of four types of deltamethrin-treated nets, over a 6-month period of domestic use with washing every 2 weeks, in a rural area of Iran

Abstract

In a randomized, prospective, 6-month-long field study in a rural area of Iran, the wash resistances of 200 nets (40 PermaNet, 40 Yorkool and 40 A-Z nets), that their manufacturers claimed be long-lasting insecticidal nets (LLIN), were compared with those of 40 nets conventionally treated with deltamethrin (using K-O Tab tablets). All the nets were kept in routine domestic use and subjected to standardized hand-washing at 2-week intervals. Wild-caught or laboratory-reared Anopheles stephensi were used for the bio-assays of insecticidal activity. The regular washing and domestic use led to reductions in the insecticidal activities of all the treated nets after 6 months. Although the PermaNet nets showed the smallest reduction, they were not significantly better than the conventionally treated nets, which still showed acceptable insecticidal activity after 6 months. The PermaNet and A-Z nets both performed significantly better than the Yorkool nets, which were slightly but not significantly worse than the conventionally treated nets. In questionnaire-based interviews, the local householders were found to wash their own (non-study) nets at median and mean frequencies of every 2 and 2.1 weeks, respectively. In conclusion, the PermaNet nets showed better wash resistance than any of the other commercial nets, and were the only commercial nets tested that truly appeared to be LLIN. There still appears to be scope, however, for the impregnation, and thus the wash-resistance, of even the PermaNet nets to be improved.

Entomological evaluation of PermaNet 2.0®and K-O Tab 1-2-3®treated nets in comparison to nets conventionally treated with deltamethrin, after repeated washing

“…In previous studies, the wash resistance of PermaNet2 was found to be similar to the results of wash resistance of PN2 (new generation of PermaNet2) up to 15 washes. 2,17,18,20,21 In the present study, the results showed better wash resistance of PN2 in comparison to PermaNet2 up to 21 washes. 21 22,23,26 In two studies that were carried out by Yates et al and Oxborough et al on wash resistance of KO 123, although their studies were laboratory based and they used WHO laboratory washing methods, they reported similar results to our study and confirmed that KO 123 is LLITNs.…”

Optimization of pyrethroid and repellent on fabrics against Stegomyia albopicta (=Aedes albopictus) using a microencapsulation technique

“…Insecticide‐treated fabrics, including those used in combat uniforms and nets, have always been considered to represent the most promising form of protection against mosquito species of public health importance (Rozendaal, ). Currently, the only group of pesticides recommended for treating fabrics is that of pyrethroids, which includes permethrin, deltamethrin, lambdacyhalothrin, alpha‐cypermethrin, cyfluthrin and etofenprox, because they have strong insecticidal activity and low mammalian toxicity (Zaim et al ., ; World Health Organization, ; Müller et al ., ; Kayedi et al ., ). However, laboratory studies indicate that fabrics impregnated with pyrethroids do not prevent vector mosquitoes from landing and therefore mosquito vectors may obtain a bloodmeal through wide‐meshed nets or holed fabrics before knock‐down (Cooperband & Allan, ).…”

Synergistic insecticidal and repellent effects of combined pyrethroid and repellent-impregnated bed nets using a novel long-lasting polymer-coating multi-layer technique

“…Synthetic ester, non-ester and α-cyano pyrethroids, e.g. permethrin, etofenprox, deltamethrin, cyfluthrin, λ-cyhalothrin and α-cypermethrin, are recommended by the World Health Organization (WHO 2005(WHO , 2011c) at substance-specific application concentrations and are widely employed for insecticidal treatment of LLINs (Muller et al 2002;Kayedi et al 2007). Recent data showed that LLIN use may directly influence abundant mosquito population density with reduction rates up to 50 % in case that LLIN coverage rates within the affected population exceed 80 % (White et al 2011).…”