[Use and effectiveness of long-lasting insecticide-treated nets (LLINs) in southern Cameroon].

BACKGROUND

Long-lasting insecticidal nets (LLINs) are widely used in sub-Saharan Africa to reduce the transmission of malaria. Their operational lifespan under field conditions depends on many factors. This article presents some of the factors associated with the decline in LLIN efficacy in urban and rural settings in Kribi, southern Cameroon.

METHODS

This study, conducted in 2019, aimed to evaluate the usage and residual efficacy of the nets against two strains of Anopheles gambiae s.l.: a local strain with an unknown insecticide susceptibility status and a sensitive reference laboratory strain.

RESULTS

A total of 540 households were surveyed. LLIN coverage was similar in rural (69.0%) and urban (68.6%) areas. The proportion of children under five years of age using LLINs was comparable in both settings (88.6%: 651/735). PermaNet 2.0 nets were more degraded than other brands in rural areas, while Yorkool nets were more degraded in urban areas. Mortality rates for the Kisumu strain ranged from 21.6% to 99.6% for LLINs that had been washed more than 20 times, and from 0.8% to 76.5% for the wild-type strain. Those washed with bar soap retained their lethal properties better than those washed with harsh detergents. Similarly, nets dried in the shade retained their lethal properties better than nets hung out in the sun.

CONCLUSION

The study population used MILDAs, especially for children. The fiber composition of the nets, the type of detergent used, and exposure to sunlight are factors that influence the insecticidal efficacy of the nets.