Epidemic typhus rickettsiae isolated from flying squirrels

Abstract

EPIDEMIC typhus is a severe rickettsial infection that classically has involved only man and his body louse. Although the aetiological agent, Rickettsia prowazekii, has been isolated from ticks of domestic animals and from blood of livestock in Ethiopia and Egypt^1,2, infection of these unusual hosts and vectors has been thought to be secondary to active dissemination of the louse-borne disease in the human population³. Ormsbee concluded that livestock and the equivalent wild species were unlikely to be important in the ecology of epidemic typhus⁴. This disease was last reported in the eastern United States in Philadelphia in 1836 (ref. 5). We have now isolated six strains of R. prowazekii from the eastern flying squirrel (Glaucomys volans volans). This finding suggests that an extrahuman reservoir of epidemic typhus can exist in a species of wild rodent independent of the recent occurrence of epidemic or sporadic disease.