Louse resistance to insecticides

Typhus and relapsing fever are spread by the body louse, Pediculus humanus, which has shown increasing resistance to insecticides, thus threatening the effectiveness of typhus control campaigns. Some other species of lice which threaten the health of domestic animals have also shown signs of resistance.

The body louse first showed resistance to insecticides in 1950 in South Korea and Japan. By 1955 resistant strains had appeared in South America and west Africa, and by 1958 in India.