Short and long term evaluation of the efficiency of PermaNet ???? 2.0 bed net against environmental factors and washing using bioassay tests

摘要

ABSTRACT The aim of the present study was to examine the resistance of PermaNet ???? 2.0 bed nets against repeated washing and environmental factors by using bioassay tests. After 5, 15 and 21 washings with detergents and by using bioassay tests, the resistance of 40 PermaNet ???? 2.0 bed nets was compared with that of 40 bed nets conventionally treated with one K-O tablet. To examine the long-term resistance, 31 PermaNet ???? 2.0 bed nets were also distributed among villagers, and were re-collected to perform bioassay tests after 1, 2 and 5 years. In the first phase of this study, the insecticidal effect of the conventionally-treated nets significantly decreased due to repeated washings (P < 0.001); however, it was not significant regarding PermaNet ???? 2.0 bed nets (P = 0.92 in continuous exposure and P = 0.12 in mortality tests). In the long-term phase of this study, the time required for knockdown of PermaNet ???? 2.0 increased over the first 2 years and then decreased. In addition, the mortality rate decreased over the first 2 years and then increased. In conclusion, it seems that the technique used by the manufacturer for impregnation of PermaNet ???? 2.0 bed nets has an acceptable efficiency in comparison with conventional techniques.