Objective: To document the histology of Ross River virus (RRV) arthritis and to examine inflamed synovium for viral RNA.
Methods: Biopsy tissue from the inflamed knees of 12 patients with RRV infection was studied using conventional and immunostaining techniques. Reverse transcriptase-polymerase chain reaction technology was used to probe for the presence of viral RNA in the synovial biopsy samples and in serum.
Results: Hyperplasia of the synovial lining layer, vascular proliferation, and mononuclear cell infiltration were the main histologic changes. RRV RNA was found in knee biopsy tissue that was obtained from 2 patients at 5 weeks after the onset of symptoms.
Conclusion: RRV RNA was identified in inflamed synovium more than a month after symptoms began. Inflammation was apparent in the absence of detectable virus in the majority of patients.