Bold (and unfounded) statements

I just read these first two opening lines of a 2014 paper by Tokponnon et al.

“The widespread use of insecticide-treated nets (LLINs) leads to the development of vector resistance to insecticide. This resistance can reduce the effectiveness of LLIN-based interventions and perhaps reverse progress in reducing malaria morbidity.”

I first read this as: “Using insecticide treated nets reduces their effectiveness which could increase malaria”. A somewhat misleading start to a paper that concluded that there was actually decreased malaria prevalence in areas with high mosquito insecticide resistance.

I doubt that pyrethroid resistance is mainly caused by using insecticide treated bed nets. Typically the main suspect for increasing resistance is either large scale spraying of pyrethroids often for agricultural purposes, and this is particularly true in Benin where this study took place.

Is it possible that the number of bed nets deployed could make enough of a dent on mosquito populations to be the main selective driver for resistance? It’s worth debating, but this paper didn’t show that resistance was a problem. In fact, either because of local environmental differences of even behavioral differences (like biting at different times of day for example when people aren’t under nets) they found more susceptible mosquito populations were actually transmitting more malaria parasites even with the same LLIN coverage and use. Should we worry about insecticide resistance? Maybe, but I think more studies like this one would be very useful to judge how much we should worry.

Leave a Reply