Rickettsia australis, transmitted by the Ixodes holocyclus, Ixodes tasmani, and Ixodes cornuatus ticks, is a member of the spotted-fever group of Rickettsiae. It causes Queensland tick typhus (QTT), which is only endemic to eastern Australia. It has been reported in both Australians and travelers to eastern Australia.

Patients develop a febrile syndrome with headache and myalgias 1-11 days (mean 5 days) after a tick bite. A diffuse rash follows accompanied by an eschar at the site of the tick bite in one-half to two-thirds of cases. Occasionally, QTT may be "spotless." Lymphadenopathy adjacent to the bite may be present 50%-75% of the time. Hepatomegaly and splenomegaly may be observed as well. Laboratory abnormalities include thrombocytopenia, hyponatremia, renal insufficiency, and transaminitis. At least one fatality has been reported. Complications such as renal failure, pneumonia, and purpura fulminans may rarely occur.

Males are more often infected than females, more patients are affected in the winter and spring months, and up to 90% of patients may give a history of a tick bite.