Abstract:
Malaria control in sub-Saharan Africa has stagnated despite widespread adoption of control measures
such as long-lasting insecticidal nets (LLINs). Progress has stalled, in part, because of pyrethroid insecticide resistance,
driving the need for retooling to increase the effectiveness of bed nets. Consequently, LLINs have been treated with
the chemical synergist piperonyl butoxide (PBO). Piperonyl butoxide LLINs have been shown to be efficacious
in controlled settings; however, their effectiveness in real-world settings warrants investigation. In Bungoma County,
Western Kenya, a cohort of 768 participants was followed from June 2017 to December 2023 via active and
passive surveillance. Household visits were conducted monthly, during which LLIN use for nets distributed in 2017 and
2021 was recorded, and symptomatic malaria cases were identified using rapid diagnostic tests (RDTs). The comparative
effectiveness of PBO versus conventional LLINs was assessed in terms of malaria infections. A multilevel logistic regression model was fit with monthly RDT results as the dependent variable. The study results indicate that PBO LLINs provide greater protection against malaria at the individual level than conventional LLINs (odds ratio: 0.70; 95% CI: 0.47–
1.03), although the findings were not statistically significant. The added protection against malaria infections provided by
PBO LLINs compared with conventional LLINs observed in the current study aligns with findings from most previous
studies, although this finding was not statistically significant. In areas with documented pyrethroid resistance, the use of
LLINs with an added synergist, such as PBO, can provide additional protection against malaria infections (compared
with pyrethroid-only LLINs) and should be considered for scaled-up scenarios despite the additional cost.
