Effectiveness Of Long-lasting Insecticidal Nets Washed With Non-standard Washing Procedure

Objective:To explore the effectiveness of long-lasting insecticidal nets (LLIN)(PermaNet(?)2.0) washed with non-standard washing procedure by local resident in Yunnan in order to provide evidence for further promote and extend the application of LLIN.Methods:To select villages with high LLIN coverage and better mosquito nets use behavior target by free distribution of LLIN (PermaNet(?)2.0) by Global Fund malaria project. To collect LLINs which meet the study protocol requirements, especially washing times by door to door surveys and conduct bioassay tests by clipping fixed size according to the WHO test tubes (cylinders). Mortality,1 hour Knock down and KD50 were calculated.Results:24 hours mortality of Anopheles minimus exposured to unwashing LLIN (PermaNet(?)2.0) was 100%,60-minute mean knockdown rate was 100%. The mortality of five times washed LLIN dropped to 90%. mortality after 10 washing times dropped to 89%,mortality after 15 and 20 washing times was 90% and 85%.60 minutes average knockdown rate were 94%,96%,98% and 93% after washing 5,10,15 and 20 times of mosquito nets, respectively. KT50 of Anopheles minimus were 33.79,33.91,34.30 and 37.25 minutes among washing 5,10,15 and 20 times, respectively. The study showed 78 (95.12%) out of 82 samples were dry under the sun directly when nets were washed, and the remaining 4 (4.88%), both dry under the sun, but also dried in the shade. There were 37 (45.12%) out of 82 samples physically damaged..Conclusion:The study found the effectiveness of LLIN affected by washing factors among local residents from risky group in malaria endemic areas of Yunnan. The more washing activities, the lower trend of effectiveness of LLIN (PermaNet(?)2.0). The LLIN (PermaNet(?)2.0) samples collected from field of Yunnan meet WHO criteria for product quality requirements.