Rheumatic fever

Acute rheumatic fever is an inflammatory illness that develops a couple of weeks after an untreated or inadequately treated throat infection with group A streptococcus. In susceptible people, the antibodies made against the bacterium cross-react with the body's own tissues — a case of mistaken immune identity — inflaming the joints, heart, skin and nervous system. It mainly affects children and young people and is now uncommon in high-income countries (thanks to prompt antibiotic treatment of strep throat) but remains an important cause of heart disease worldwide. The features include fever, a migrating arthritis that moves from one large joint to another, and inflammation of the heart (carditis) affecting the valves, muscle or lining. Less common features are a distinctive rash, small skin nodules, and a movement disorder called Sydenham's chorea. The most serious consequence is damage to the heart valves — rheumatic heart disease — which can appear or worsen years later. Diagnosis uses a recognised set of criteria combining these clinical features with evidence of a recent strep infection (such as a raised or rising ASO antibody) and inflammatory markers. Treatment addresses the strep infection, the inflammation and the joint symptoms; because further strep infections can trigger recurrences and more heart damage, long-term preventive antibiotics are often given. The key to prevention is treating strep throat promptly.

• Anti-streptolysin O (ASO) — evidence of a recent strep infection; a raised or rising level supports the diagnosis.
• CRP and ESR — inflammatory markers, typically raised during the acute illness.
• Throat swab — may still detect strep, though the infection has often cleared.
• ECG and echocardiogram — assess heart involvement (carditis) and valve damage.

• Fever
• Painful, swollen joints that migrate from one large joint to another
• Signs of heart inflammation: chest discomfort, breathlessness, a new murmur
• A distinctive rash and small painless skin nodules (less common)
• Jerky, involuntary movements (Sydenham's chorea)
• Often a preceding sore throat a couple of weeks earlier