Barmah Forest virus infection case definition

This document contains the case definitions for Barmah Forest 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

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

2. Members agreed to add to the end of point 5 under Laboratory definitive evidence 'Detection of Barmah Forest virus IgM in the presence of Barmah Forest virus IgG'.

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

Barmah Forest 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 Barmah Forest virus


Detection of Barmah Forest virus by nucleic acid testing


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

Laboratory suggestive evidence

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

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