Rickettsioses in Australia: Isolation of Rickettsia Tsutsugamushi and R. Australis from naturally infected arthropods

The vectors of scrub typhus and Queensland tick typhus have not previously been positively identified in Australia. Small mammals were trapped at Mossman (north Queensland) and 4 strains of Rickettsia tsutsugamushi were isolated in mice inoculated with suspensions of Leptotrombidium deliense removed from bandicoots. No strains were isolated from unfed, larval L. deliense collected from the forest floor, but 21 further strains were obtained from tissues of 141 animals of 5 species. A focus of infected ticks was defined when cases of Queensland tick typhus were identified in soldiers at Canungra (S.E. Queensland). Rickettsia australis was subsequently isolated in suckling mice from 2 pools of scrub ticks (Ixodes holocyclus) and 1 pool of I. tasmani.