Australian national notifiable diseases case definitions
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.
Communicable Diseases Surveillance
(Effective 1 January 2013)
Reporting
Only a confirmed case should be notified.Confirmed case
A confirmed case requires laboratory definitive evidence only.Laboratory definitive evidence
Isolation of Barmah Forest virusOR
Detection of Barmah Forest virus by nucleic acid testing
OR
IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to Barmah Forest virus
OR
Detection of Barmah Forest virus-specific IgM, in the absence of Ross River virus IgM, unless Barmah Forest virus IgG is also detected.
OR
Detection of Barmah Forest virus-specific IgM in the presence of Barmah Forest virus IgG.
Barmah Forest virus infection changes
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 IgM to Ross River IgM, virus unless Barmah Forest virus IgG is also detected'.
Add point 5 under Laboratory definitive evidence 'Detection of Barmah Forest virus IgM in the presence of Barmah Forest 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.
