Successful use of a Janus-kinase (JAK) inhibitor in chronic chikungunya arthritis refractory to conventional synthetic DMARDs: a case report.

Chronic chikungunya arthritis is a debilitating post-viral inflammatory condition that clinically mimics rheumatoid arthritis and often requires long-term treatment with disease-modifying antirheumatic drugs. Treatment options are limited when conventional synthetic disease-modifying antirheumatic drugs are not tolerated or lose efficacy. We report the case of a 50-year-old Brazilian woman with serologically confirmed chikungunya virus infection who developed chronic chikungunya arthritis with a rheumatoid arthritis-like phenotype. Following an acute febrile illness accompanied by rash and negative dengue serology, she was initially managed with symptomatic analgesics, followed by prednisone and hydroxychloroquine. Despite this treatment, the disease activity score in 28 joints calculated with C-reactive protein was elevated at 6.78. Methotrexate was introduced but was discontinued after three weeks due to drug-induced pneumonitis. She later failed leflunomide therapy after 12 months, with a score of 4.33. Baricitinib (4 mg/day), a Janus kinase 1 and 2 inhibitor, was then initiated, resulting in marked clinical and laboratory improvement: the disease activity score decreased to 1.90 over one year, C-reactive protein normalised and the erythrocyte sedimentation rate declined progressively, and morning stiffness resolved, with no infectious complications. This case suggests that Janus kinase inhibition may be a therapeutic option for selected patients with chronic chikungunya arthritis refractory to conventional treatment.