SEASONAL ONSET OF SYSTEMIC-ONSET JUVENILE RHEUMATOID-ARTHRITIS

Objective: This study was undertaken to investigate the recent finding of a seasonal difference in the onset of systemic-onset juvenile rheu matoid arthritis (SoJRA). We hypothesized that a seasonal onset patter n might implicate an infectious agent as a cause of SoJRA. Methods: Th e date of onset was collected from the records of all patients with So JRA from 1980 to 1992 at presentation to pediatric rheumatology clinic s across Canada. The onset pattern of SoJRA was then compared with inc idence data on viral infections obtained for the same period. Results: Across Canada the onset of SoJRA was constant across the seasons. How ever, in the Prairie region there was a statistically significant seas onal pattern, with peaks in autumn and early spring. We could find no evidence that viral incidence correlated with disease incidence either throughout Canada or in the Prairie region. Conclusions: If a seasona l infectious agent causes SoJRA, then it is likely only one of several causes and may act only in certain regions. Future studies should be carried out in those areas where SoJRA does have a seasonal onset patt ern.