Permethrin Plus Pyriproxyfen-Treated Bednets Reduce Malaria Transmission

Long-lasting insecticidal nets treated with permethrin plus pyriproxyfen (PPF) are more effective in preventing clinical malaria compared with standard long-lasting insecticidal nets, according to study results published in The Lancet.

PPF-treated long-lasting insecticidal nets present a viable alternative to its standard counterpart in areas that have high transmission rates of Plasmodium falciparum malaria and highly pyrethroid-resistant vectors.

This study included 40 rural clusters in Burkina Faso, an area with intense malaria transmission and highly pyrethroid-resistant vectors, with 50 children age 6 months to 5 years in each cluster. During the study, the researchers incrementally replaced standard nets with long-lasting insecticidal nets treated with PPF. The researchers followed up with participants via passive case detection for clinical malaria.

The investigators performed cross-sectional surveys at the beginning and end of the transmission season in 2014 and 2015. They performed monthly collections from indoor light traps to estimate vector densities. The primary end points were the incidence of clinical malaria as measured by passive case detection and the entomologic inoculation rate.

In 2014, the cohort included 1980 participants; in 2015, the cohort included 2157 participants. By the end of the study period, 99% of participants slept under a long-lasting insecticidal net.

In the standard long-lasting insecticidal net group, the incidence of clinical malaria was 2.0 episodes per child-year compared with 1.5 episodes per child-year in the PPF-treated long-lasting insecticidal net group (incidence rate ratio 0.88 [95% CI 0.77-0.99; P =.04]).

The standard long-lasting insecticidal net group had an entomologic inoculation rate of 85 (95% CI, 63-108) infective bites per transmission season compared with an average of 42 (32-52) infective bites per transmission season in the PPF-treated long-lasting insecticidal net group (rate ratio 0.49; 95% CI, 0.32-0.66; P <.0001).

“In Burkina Faso, 6,014,021 uncomplicated malaria cases in children younger than 5 years were recorded in 2017; thus, a 12% reduction in malaria incidence due to use of PPF-treated long-lasting insecticidal nets would equate to 721,683 cases averted,” the researchers wrote.

Reference

Tiono AB, Ouedraogo A, Ouattara D, et al. Efficacy of Olyset Duo, a bednet containing pyriproxyfen and permethrin, versus a permethrin-only net against clinical malaria in an area with highly pyrethoid-resistant vectors in rural Burkina Faso: a cluster-randomised controlled trial. [published online August 10, 2018]. Lancet. doi:10.1016/S0140-6736(18)31711-2