Characterisation of the clinical forms of chronic chikungunya: an observational cohort study in Rio de Janeiro.

OBJECTIVES: This study aimed to characterise the clinical presentation of acute and chronic chikungunya virus infection in Brazil and identify predictors of chronic chikungunya. METHODS: We conducted a prospective observational cohort study in the emergency department of Hospital Quinta D'Or, Rio de Janeiro, between March 2016 and May 2017. Adults with suspected chikungunya were tested by RT-PCR for chikungunya, dengue, and Zika viruses. Patients with laboratory-confirmed chikungunya were enrolled. Clinical and demographic data were collected at baseline. At 90 days (D90), participants completed telephone follow-up assessing persistent symptoms, pain, and quality of life. Chronic disease was defined as ongoing arthralgia or myalgia at D90. RESULTS: Among 134 PCR-confirmed cases, 100 completed follow-up and 38% reported chronic manifestations. Female sex (adjusted OR 2.56, 95% CI 1.02-6.25) and increasing age (adjusted OR 1.04, 95% CI 1.01-1.07) were independently associated with chronic disease. Prostration and retro-orbital pain showed trends towards association. Chronic symptoms were associated with pain interference affecting mood, work, and sleep. CONCLUSIONS: Over one-third of adults with laboratory-confirmed chikungunya experienced persistent symptoms at D90, with substantial functional impact. Early identification of patients at risk may support targeted follow-up and integration of long-term care into arboviral disease management.