Acute Barmah Forest polyarthritis.

More than 60 arboviruses have been isolated in Australia with the human pathogenicity of the majority yet to be determined. Recent reports outline extensive clinical and sub-clinical infection occurring in Eastern Australia by such agents as Ross River and Barmah Forest viruses. We describe the clinical features of two patients with an acute polyarthritis associated with serological evidence of acute Barmah Forest virus infection to alert physicians to this form of viral polyarthritis and highlight the need to consider this agent when confronted with patients with an acute 'viral-type' polyarthritis in whom serology for Ross River virus is negative.