Evaluation of Long-Lasting Insecticidal Nets (DuraNet®) Under laboratory and Semi-Field Conditions Using Experimental Huts Against Anopheles Mosquitoes in Jimma Zone, Southwestern Ethiopia

Abstract

Background: Long-Lasting Insecticidal Nets (LLINs) efficacy could be compromised due to a lot of influences together with user compliance and vector population insecticide resistance status. Thus, this study was to assess the biological efficacy of DuraNet® with the help of the World Health Organization cone bioassay and field experimental hut. Methods: A laboratory and a semi-field conditions experimental huts against Anopheles Mosquitoes were conducted in southwestern Ethiopia from September 2015 to January 2016. The bio efficacy of DuraNet® was evaluated using the WHO cone bioassay test and then its field efficacy was evaluated using experimental huts against the malaria vector population. Results: World Health Organization cone bioassay tests against pyrethroid-resistant An. arabiensis led to mean percent mortality and knockdown of 78% and 93%, respectively. Washing of DuraNet® successively reduced its efficacy from 93% knockdown (0 wash) to 45% knockdown (20 washes). Similarly, mean mortality decreased from 84% (0 wash) to 47% (20 washes). A total of 1575 female mosquitoes were collected over 40 nights out of which 1373(87.8%) were An. gambiae s.l., 116 (7.4%) were Anopheles coustani and 107 (6.8%) were An. pharoensis. The mean blood-feeding rate was significantly lower ( P < .001) in hut containing unwashed DuraNet® when compared to hut containing untreated DuraNet®. The mean mortality rate was significantly higher ( P < .001) in hut containing DuraNet® when compared to hut containing untreated DuraNet®. Unwashed DuraNet® showed the highest personal protection 88.7% and 100% against An. Arabiensis and An. pharoensis, respectively. Conclusion: Both DuraNet® and PermaNet 2.0 moderate efficacy against a pyrethroid-resistant population of An. arabiensis from Ethiopia. The bio efficacy of DuraNet® was found below the WHO recommendation. Therefore, the real impact of the observed insecticide resistance against DuraNet® to be further studied under phase-III trials, the need for new alternative vector control tools remains critical.