Flying squirrels and their ectoparasites: disseminators of epidemic typhus

Information gathered during the past decade indicates that the eastern flying squirrel, Glaucomys volans, is a zoonotic reservoir of Rickettsia prowazekii - causative agent of louse-borne (epidemic) typhus. The sporadic cases o f typhus that have occurred in the USA in association with flying squirrels provide evidence that flying squirrels can transmit R. prowazekii infection to humons. Strains of R. prowazekii, isolated from flying squirrels multiply readily in human body lice, but flying squirrel lice, although readily infected, are very host specific and tend not to bite humans. It may be that the infection is spread to humans in infective ectoporasite faeces aerosolized when the flying squirrels groom themselves. As Joseph McDade emphasizes in this article, current concepts of typhus epidemiology and control must be re-evaluated to take into account this zoonotic aspect.