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Scrub Typhus A009

Last amended 
29 October 2018

In this section

Current RMA Instruments

Reasonable Hypothesis SOP

77 of 2018

Balance of Probabilities SOP

78 of 2018

Changes from previous Instruments

SOP Bulletin 204

ICD Coding

  • ICD-9-CM Codes: 081.2
  • ICD-10-AM Codes: A75.3

Brief description

This is an infection, presenting as an acute febrile illness.  It is transmitted by the bite of a trombiculid mite (a small arachnid), which carries the causative organism - Orientia tsutsugamushi (previously called Rickettsia tsutsugamushi).  It is endemic in localised areas of Asia/the Pacific rim and is present in geographically focal parts of northern Australia.

Confirming the diagnosis

Diagnosis is based on the clinical presentation, the history of being in an endemic area, and serology or polymerase chain reaction testing.  A biopsy of the skin reaction at the site of the bite (eschar) or the subsequent rash may also be undertaken.

Diagnosis can be made by a GP. The relevant medical specialist is an infectious diseases physician.

Additional diagnoses covered by SOP

  • Mite born typhus
  • Tsutsugamushi fever

Conditions excluded from SOP

  • Louse born typhus#
  • Murine (flea borne) typhus#
  • Q fever#
  • Queensland tick typhus#
  • Spotted fever#
  • Tick borne typhus#
  • Typhoid#
  • Typhus#

# non-SOP condition

Clinical onset

Time of clinical onset will be based on the symptoms (typically fever, headache, myalgia and rash) which develops typically 7 to 10 days after a bite from an infected mite.

Clinical worsening

The only SOP worsening factor is for inability to obtain appropriate clinical management.  The condition, untreated, generally resolves after 14 to 21 days, although complications may develop and death can occur.  The condition usually responds well to appropriate antibiotics.