The protective effect of bed nets impregnated with pyrethroid insecticide and vaccination against Japanese encephalitis.

A population-based case-control study to evaluate the protective effect of bed nets impregnated with pyrethroid insecticide and of vaccination against Japanese encephalitis was carried out in Gusi county, Henan province, China from June to September 1991; 50 cases and 100 matched controls were studied. Bed nets impregnated with pyrethroid insecticide greatly decreased the risk of infection among children under 10 years old, and vaccine efficacy was 78% (95% CI 16%-94%). We suggest that impregnated bed nets could be used as a quick response during outbreaks of Japanese encephalitis.