Evaluation of the Performance of K-OTAB (Deltamethrin Tablet Formulation) Impregnated Bednets against the Malaria Vector Anopheles (Cellia) superpictus Grassi 1899 (Diptera: Culicidae) under Laboratory Conditions


Abstract: The efficacy of K-OTAB (deltamethrin-tablet formulation) impregnated bednets was evaluated against the malaria vector Anopheles (Cellia) superpictus Grassi 1899 (Diptera: Culicidae) under laboratory conditions. The experiments were carried out with 3 main tests: susceptibility, bioassay, and washing tests. Deltamethrin treated nets in WHO test kits in susceptibility test 1 showed remarkable efficacy (89.5%) 1 h after the treatment and efficacy was 100% at the end of 24 h. The results demonstrated significant differences in mortality between different time intervals. Average mortality started to increase just after 15 min; it was 61% after 30 min, reaching 82% after 45 min and peaked to mass mortality rate at the end of 24 h. Efficacy against An. superpictus ranged from 90% to 100%, depending on different exposure periods in susceptibility test 2. The increase in mortality rates was exponential until 45 min exposure. The highest mortality rates were found at 45 and 60 min exposure times in the range of 95%-100%. Bioassay tests revealed gradual mortality ranged from 70% to 90%. The treatment efficacy was considered to be more dependent on the amount of washing than on the time after the treatment. The treated nets exhibited slightly poorer efficacy after the second and third washes, showing a decline from an initial value of 90% (unwashed) to 76.6% within 24 h of exposure after the second wash and to 75% after the third wash. The loss in effectiveness was within acceptable limits (13.4%-15%) compared with the loss in active ingredient (60%) after the second wash.

Keywords: Malaria, Anopheles superpictus, bednet, deltamethrin, laboratory tests

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