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Objective To determine the wash resistance of Olyset
ABSTRACT
OBJECTIVE@#To determine the wash resistance of Olyset Plus using World Health Organization Pesticide Evaluation Scheme standard washing procedure and to assess the value of knock down and mortality rates of Anopheles stephensi at different regimens of long lasting insecticide treated nets washings.@*METHODS@#The study was conducted at the Bioassay Laboratory of Culicidae Insectary, School of Public Health, Tehran University of Medical Sciences, Iran. The net was made of polyester impregnated with permethrin and piperonyl butoxide at a ratio of 2:1. The washing resistance was assessed using Le Chat soap and a shaker incubator set at a speed of 155 r/min, 30 °C for 10 min. The cone bioassay test was carried out according to World Health Organization recommended guideline with tolerant field strain of female Anopheles stephensi to pyrethroids.@*RESULTS@#The knockdown and mortality rates of female mosquitoes exposed to Olyset Plus from un-washed nets to 2 washings were 79.7% and 88.8% respectively. Mortality was dropped to zero while active ingredient estimated 0.532 μg/100 cm to 0.481 μg/100 cm after 15 washings. A positive correlation was seen between residues of permethrin on nets, knockdown rate and mortality rate of female Anopheles stephensi exposed to different regimes of washed Olyset Plus (r = 0.954, P = 0.001).@*CONCLUSIONS@#It is recommended that a preliminary survey conducted on resistance level of Anopheles vectors before the distribution of Olyset Plus in malaria endemic communities.
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Background & objectives: In the present study, Icon®Life net, a long-lasting polyethylene net, 100 denier and bursting strength of minimum 280 kpa incorporated with deltamethrin @ 65 mg/m2 was evaluated for its efficacy in reducing the density of malaria vector Anopheles culicifacies and impact on malaria prevalence in a malaria endemic area of District Gautam Budh Nagar, India. Methods: Wash resistance of Icon® Life LLIN was determined up to 20 serial washings using An. culicifacies in cone bioassays under field conditions. Efficacy of Icon®Life LLIN was determined in the field in three sets of villages in District Gautam Budh Nagar (Uttar Pradesh), India, selected randomly for the intervention with Icon®Life LLIN, untreated nets and a control without any intervention for the period of August 2008–July 2009. Entomological and malariometric indices in all the three villages were compared during pre- and post-intervention periods for one year against An. culicifacies. A survey was also conducted in the village provided with Icon® Life LLIN to assessing the perception of community regarding acceptance of these nets by the community. Results: In cone bioassays on Icon®Life LLIN with An. culicifacies, >95% knockdown within 1 h and 100% mortality after 24 h exposure were reported even after 20× serial washings under field conditions. Results of the field study revealed reduced entry rate, resting density and parity rate of An. culicifacies in the village with Icon®Life LLIN when compared to no net and untreated net villages. Number of malaria cases reported were less in the Icon®Life LLIN used villages when compared to other two villages. The community compliance and acceptance was high and no adverse health events were reported by the households using these nets. Conclusions: Icon® Life LLIN is an effective intervention for the control of An. culicifacies transmitted malaria in India. Long-term studies are indicated for the duration of effectiveness and to ascertain the epidemiological impact of the use of Icon® Life nets.
ABSTRACT
Five insecticides (Bifenthrin, Deltamethrin, Etofenprox, Permethrin and Lamda cyhalothrin) recommended by WHO, at their recommended dose were compared for their efficacy and wash resistance through bioassay against mosquito vectors, Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. Etofenprox treated nettings exhibited better knockdown and mortality than the other insecticides. The order of efficacy of the insecticides treated nettings was Etofenprox ≥ Deltamethrin > Lambda cyhalothrin > Permethrin > Bifenthrin.