Anakinra therapy in a child with systemic-onset juvenile rheumatoid arthritis after human herpesvirus 6 encephalitis.

A 3-year-old patient with biopsy-proven herpesvirus 6 (HHV-6) encephalitis developed a clinical condition consistent with systemic-onset juvenile idiopathic rheumatoid arthritis (SoJIA) and responsive to synthetic interleukin-1 (IL-1) receptor therapy. This suggested both a temporal relationship between HHV-6 infection and the development of SoJIA and the likely involvement of IL-1 in his disease. This case adds to the current experience of IL-1 receptor antagonist therapy in SoJIA. In addition, it suggests that future prospective studies in new-onset SoJIA should include an evaluation for HHV-6 infection.