Acute rheumatic fever most commonly occurs in which age group and presents with which features?

• A. Adults with chest pain
• B. Infants with jaundice
• C. Less than 15 years old; migratory polyarthritis and carditis
• D. Elderly with dementia

Answer: (C)

Acute rheumatic fever is an immune-mediated consequence of untreated group A streptococcal infection, most common in children. The key idea is that it typically affects those who are under 15 years old, and the hallmark presenting features are migratory polyarthritis and carditis. Migratory polyarthritis means the arthritis moves from joint to joint, usually involving large joints, over days to weeks. Carditis reflects inflammation of the heart’s lining and valves and can manifest as new heart murmurs or signs of heart involvement. While other features like chorea or skin findings can appear, the combination of a young patient and the characteristic joint-and-heart involvement makes this presentation classic. The scenarios described in adults with chest pain, infants with jaundice, or elderly individuals with dementia do not align with the typical age range and symptom pattern of acute rheumatic fever.