Jones criteria

**Pathophysiology:** ARF is a type II hypersensitivity reaction caused by molecular mimicry. Antibodies and T cells against the GAS M protein cross-react with host antigens (myosin, tropomyosin, laminin, valvular endothelium, basal ganglia). It occurs about 2-4 weeks after GAS pharyngitis. It does NOT follow GAS skin infection (impetigo), which instead causes post-streptococcal glomerulonephritis. Peak age is 5-15 years. Histology shows Aschoff bodies (granulomas with Anitschkow cells, or "caterpillar cells") in the myocardium. Rheumatic heart disease is a pancarditis, but the mitral valve is most commonly affected (MS is the classic chronic sequela), followed by the aortic valve.

**Evidence of preceding GAS infection (required):** Positive throat culture or rapid antigen test, elevated or rising ASO or anti-DNase B titers, or recent scarlet fever. (Exceptions: chorea and indolent carditis may present late, when serologies may have normalized.)

**Major criteria (JONES):** - **J**oints: migratory polyarthritis of large joints (most common major criterion). It responds dramatically to NSAIDs/aspirin and does not cause permanent damage. - **♥** Carditis: pancarditis (endocarditis, myocarditis, pericarditis). It may present as a new murmur (e.g., mitral regurgitation, Carey-Coombs murmur), heart failure, or a friction rub. It is the only manifestation that causes long-term sequelae. - **N**odules: painless subcutaneous nodules over extensor surfaces and bony prominences. - **E**rythema marginatum: non-pruritic, evanescent, serpiginous or ring-shaped rash on the trunk and proximal limbs, sparing the face. - **S**ydenham chorea: rapid, involuntary, purposeless movements (basal ganglia/caudate involvement). It is a late manifestation, appearing months after infection, and may occur alone.

**Minor criteria:** Fever, arthralgia (cannot be used if arthritis is the major criterion), elevated ESR/CRP, and prolonged PR interval (cannot be used if carditis is the major criterion).

**2015 AHA revision (current):** The criteria were stratified by population risk. - Low-risk populations: Fever ≥38.5°C; ESR ≥60 mm/h and/or CRP ≥3.0 mg/dL; monoarthralgia is not included; only polyarthritis counts as major. - Moderate/high-risk populations (ARF incidence >2/100,000 school-aged children, or all-ages RHD prevalence >1/1000): Major criteria also include monoarthritis or polyarthralgia, and subclinical carditis (echo/Doppler evidence) counts as a major criterion. Minor criteria: fever ≥38°C; monoarthralgia; ESR ≥30 mm/h and/or CRP ≥3.0 mg/dL. - Recurrent ARF: Can be diagnosed with 2 major, or 1 major + 1 minor, or 3 minor criteria, plus evidence of GAS infection.

**Management and prevention:** - Treat the GAS infection with penicillin (or amoxicillin; macrolide if penicillin allergic). - Anti-inflammatory: NSAIDs/aspirin for arthritis. Corticosteroids for severe carditis. - Secondary prophylaxis: Benzathine penicillin G IM every 3-4 weeks (or oral penicillin V). Duration depends on the severity of carditis: at least 5 years or until age 21 without carditis; 10 years or until age 21 with carditis but no residual valve disease; 10 years or until age 40 with persistent valve disease. - Primary prevention: Timely antibiotic treatment of GAS pharyngitis.

**High-yield pearls:** Carditis is the most serious manifestation. Arthritis is the most common. Chorea and erythema marginatum are specific but rare. Antibiotics for GAS pharyngitis prevent ARF but do not prevent post-streptococcal glomerulonephritis. ASO titers are useful for pharyngeal infection, while anti-DNase B is better for skin infection. Early rheumatic fever causes valve regurgitation, while chronic rheumatic heart disease causes stenosis, with "fish-mouth" mitral valve and fused commissures.