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Queensland tick typhus
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Queensland tick typhus

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Contributors: Art Papier MD, William Van Stoecker MD
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Synopsis

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.

Codes

ICD10CM:
A77.3 – Spotted fever due to Rickettsia australis

SNOMEDCT:
68981009 – Queensland tick typhus

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Differential Diagnosis & Pitfalls

Flinders Island spotted fever (FISF) is found in southeastern Australia, whereas QTT is found only in eastern Australia. FISF also less frequently presents with an eschar or lymphadenopathy.

The agents that cause Rocky Mountain spotted fever, African tick bite fever, and Mediterranean spotted fever do not exist in Australia.

Scrub typhus overlaps with QTT geographically, but scrub typhus is generally more severe (eg, encephalopathy, organ failure).

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Last Updated: 09/07/2017
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Queensland tick typhus
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Queensland tick typhus : Headache, Rash, Australia, Eschar, Lymphadenopathy, Tick bite, Myalgia
Clinical image of Queensland tick typhus
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