Significance to humans

Body louse

As the principal vector of epidemic typhus (Rickettsia prowazekii), the body louse variant is responsible for hundreds of millions of deaths up until the early nineteen hundreds. Since World War II, large outbreaks of typhus have occurred mainly in Africa, with reported cases coming predominantly from Burundi, Ethiopia and Rwanda. 

Head louse

The head louse variant is common in the western world, with infection rates exceeding 20% reported from selected primary schools in Australia, the UK and USA. However, this form is not known to transmit louse-borne diseases in natural circumstances.