||Background: An investigation carried out in Benin has shown that, in some areas close to rivers where density of
mosquitoes is high, long-lasting, insecticidal bed nets (LLINs) are permanently used. In such areas, LLINs are washed
every month. Based on this situation, the 20-wash minimum efficacy advised by the manufacturers would be inadequate.
The main goal of this study was to evaluate the effectiveness of LifeNet®, Olyset® and Permanet® 2.0 washed several times
against Anopheles gambiae sensu stricto (s.s.) populations, which have developed high resistance to pyrethroids.
Methods: Efficacy of LifeNet®, Olyset® and PermaNet® 2.0 washed 30 and 40 times was expressed in terms of
blood-feeding inhibition rate, deterrence, induced exophily and mortality rates. This WHOPES phase II evaluation,
conducted in experimental huts in Akron (southern Benin) and in Malanville (northern Benin), was accompanied
by WHOPES Phase I evaluation.
Results: Over 40 successive washes, LifeNet® induced a mortality rate over 80% in phase I. However, beyond 10
washes, Permanet® 2.0 and Olyset induced dramatically reduced mortality rates, respectively 12.5 and 2.5%. With
regard to Phase II results, unwashed LifeNet®, LifeNet® and Olyset® washed 30 and 40 times induced a similar
exophily rate per study site (at least 58% in Malanville and at least 71% in Akron). Regarding blood feeding
inhibition, LifeNet® and Olyset® washed 30 and 40 times significantly reduced wild An. gambiae s.s. blood feeding
showing a similar personal protection as unwashed LifeNet®. LifeNet® washed 30 and 40 times induced mortality
rates significantly higher than those induced by Olyset® and Permanet® 2.0 (P < 0,05).
Conclusion: LifeNet®, followed by Olyset®, have shown good efficacy against host-seeking resistant An. gambiae
s.s. population in experimental huts in Benin. Lifenet® have shown to be an effective and promising vector control
tool to prevent malaria in areas where repeated washings is a common practice in the community.