Australian national notifiable diseases case definitions
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.
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 Ross River virusOR
Detection of Ross River virus by nucleic acid testing
OR
IgG seroconversion or a significant increase in antibody level or a fourfold or greater rise in titre to Ross River virus
OR
Detection of Ross River virus-specific IgM, in the absence of Barmah Forest virus IgM, unless Ross River virus IgG is also detected.
OR
Detection of Ross River virus-specific IgM in the presence of Ross River virus IgG.
Ross River 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 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.
