Ross River virus infection case definition

This document contains the case definitions for Ross River virus infection which is nationally notifiable within Australia. This definition should be used to determine whether a case should be notified.

Page last updated: 01 January 2016

Version Status Last reviewed Endorsement date Implementation date

New probable category

Laboratory definitive evidence now only includes detection by PCR and demonstrated seroconversions. A single IgM will no longer be included in this category.

Laboratory suggestive evidence will require an IgM in the presence of IgG on the same specimen.

Single IgM positive results will no longer meet the confirmed or probable case definition.

CDWG September 2015 CDNA October 2015 1 January 2016

An assessment of notifications of Ross River virus and Barmah Forest virus infection found significant numbers of dual notifications in both jurisdictional and national data sets. It was agreed that the case definitions for Ross River virus and Barmah Forest virus infection should be made more specific.

Add to the end of point 4 under Laboratory definitive evidence 'in the absence of Barmah Forest virus IgM, unless Ross River virus IgG is also detected'.

Add point 5, 'Detection of Ross River virus-specific IgM in the presence of Ross River virus IgG'.

Classifying cases with IgM to both RRV and BFV but IgG to neither as RRV cases was considered, as the cross-reactivity problem is thought to be mainly due to false positive BFV IgM in patients with genuine RRV IgM, rather than vice versa. However it was decided that this would complicate the case definitions too much for little gain as there are likely to be relatively few such situations.

CDWG 21 September 2012 CDNA 5 October 2012 1 January 2013
1.0 Initial CDNA case definition (2004).

Ross River Virus Infection Case Definition


Both confirmed cases and probable cases should be notified.

Confirmed case

A confirmed case requires laboratory definitive evidence only.

Probable case

A probable case requires laboratory suggestive evidence only.

Laboratory definitive evidence

Isolation of Ross River virus.


Detection of Ross River virus by nucleic acid testing.


IgG seroconversion or a significant increase in IgG antibody level (e.g. fourfold or greater rise in titre) to Ross River virus.

Laboratory suggestive evidence

Detection of Ross River virus IgM AND Ross River virus IgG EXCEPT if Ross River IgG is known to have been detected in a specimen collected greater than 3 months earlier.

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