Chikungunya as a differential diagnosis of subacute and chronic polyarthritis on the pediatric population: case report

Abstract

Introduction: Chikungunya is an arboviral disease caused by the chikungunya virus (CHIKV), transmitted by Aedes aegypti and Aedes albopictus. Although usually benign, it may progress to subacute or chronic forms, posing diagnostic challenges in children. Objectives: To report an atypical case of subacute arthritis due to CHIKV in a preschool child, emphasizing its role as a differential diagnosis in pediatric arthralgia. Case description: A previously healthy 4-year-old male patient developed prolonged fever and polyarthritis after an initial febrile episode without a focal point, presenting with cumulative peripheral arthritis, dactylitis, hematological and inflammatory changes, which prompted investigation for juvenile idiopathic arthritis. Evaluation revealed tenosynovitis and synovitis in multiple joints, and serology showed positive IgM for chikungunya, confirming subacute infection by the virus. Treatment was initiated with nonsteroidal anti-inflammatory drugs (NSAIDs) and corticosteroids, and the patient was discharged with instructions to discontinue the NSAID and gradually taper off the corticosteroid. However, he experienced clinical worsening, requiring maintenance of an intermediate dose of corticosteroids and the addition of methotrexate. Fifteen months after the onset of the condition, he maintains chronic polyarthritis, raising the hypothesis of a chronic rheumatological condition post-CHIKV or JIA triggered by the viral infection. Discussion: Chikungunya can mimic other arboviral infections and pediatric rheumatologic conditions, complicating diagnosis. Although persistent arthralgia is less common in children, its impact on quality of life and development may be significant. This case underscores the need to include chikungunya in the differential diagnosis of febrile syndromes with arthritis in pediatric patients.