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Ross River virus infection A049

Document
Last amended 
25 June 2015
Current RMA Instruments:
Reasonable Hypothesis SOP90 of 2010
Balance of Probabilities SOP
91 of 2010
Changes from Previous Instruments:

ICD Coding:
  • CD-9-CM Codes: 066.3
  • ICD-10-AM Codes: B33.1
Is specific diagnostic evidence required to apply the SOP?Yes. 

Diagnosis can be complex and medical advice may be needed.  Serology results confirming recent infection are required.  There must also be a compatible clinical illness, not just positive serology.  See comments, below.

Are there sub-factors that require specific information? – No. 
Additional diagnoses covered by SOP
  • Ross river fever
  • Symptomatic Ross river virus infection - resolved (see comments)
Conditions not covered by SOP
  • Serology indicating past Ross river virus infection – N.I.F? (see comments)
  • Asymptomatic Ross river virus infection – N.I.F.
  • Post viral fatigue / chronic fatigue syndrome / other chronic symptomatology > 1 year after initial infection (see comments)
  • Barmah forest virus infection
Unconfirmed diagnosis

If, after applying the above information, you are unable to confirm the diagnosis, you should then:

  1. seek medical officer advice about further investigation, or;
  2. generate a diagnostic report, or;
  3. re-encode the condition, if appropriate.

The following investigations may be useful in establishing the diagnosis.

  • A medical report including serology testing.
Comments

The SOP applies if there is a clinical illness consistent with the disease and positive serology for recent infection.

Symptoms of Ross River virus infection:

  1. early:            joint pains, tiredness, fever, rash, myalgia, headache;
  2. persisting:    joint and muscle pains and stiffness, lethargy.

Most cases of symptomatic Ross river virus infection resolve within 3 to 6 months.  Persistence of symptoms beyond 12 months is very unusual.  Symptoms after this time are likely to be due to another condition.

A claim for previously symptomatic Ross river virus infection, with contemporary positive serology for recent infection, that has now resolved, can be diagnosed as “Ross river virus infection - resolved” and determined using the SOP.

Serology for Ross river virus infection.

  • Definitive diagnosis of recent infection requires two tests, taken approximately 10 to 14 days apart, showing a four-fold rise in IgG titre
  • Serology that is positive for both IgG and IgM is also sufficient to indicate recent infection.
  • Positive serology for IgM only, within 7 days of symptom onset, provides a presumptive diagnosis, which should be confirmed by further testing where possible.
  • Positive serology for IgG only (negative for IgM) indicates earlier or past infection.

If the only serological evidence available is positive serology for IgG (alone), that was taken some months after disease onset, the following minimum criteria should be fulfilled before confirming the diagnosis and applying the SOP:

  • Characteristic clinical illness
  • Onset of symptoms within last 12 months
  • Negative tests results for other differential diagnoses (including negative serology for Barmah forest virus)
  • Diagnosis supported by treating doctor