rheumatic fever

Rheumatic fever is a delayed immune reaction that can follow an untreated throat infection with group A streptococcus bacteria. In a case of mistaken identity, antibodies and immune cells aimed at the bacteria cross-react with the body's own tissues, attacking the joints, heart, skin, and brain. It usually appears a few weeks after the sore throat.

Its varied features are summarised by the Jones criteria. Major manifestations include carditis (inflammation of the heart), migrating arthritis of large joints, a jerky involuntary movement disorder called Sydenham chorea, a fleeting rash called erythema marginatum, and firm subcutaneous nodules. Fever, joint aches, and raised inflammatory markers support the diagnosis alongside evidence of recent streptococcal infection.

The most serious consequence is damage to the heart valves, which may not become fully apparent until years later as chronic rheumatic heart disease, especially mitral stenosis. Prompt treatment of strep throat with antibiotics prevents most cases, and people who have had rheumatic fever often take long-term preventive antibiotics to avoid recurrence. The disease has become rare in wealthy countries but remains a major cause of heart disease in many lower-income regions.