Rheumatic Fever
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Direct answer
Acute rheumatic fever is an immune-mediated inflammatory disease following pharyngitis caused by group A beta-haemolytic streptococci, in which antibodies against bacterial M protein cross-react with cardiac and other tissues (molecular mimicry). Diagnosis rests on the revised Jones criteria — two major, or one major plus two minor, manifestations with evidence of preceding streptococcal infection. The heart is the only organ left with permanent damage (rheumatic heart disease), so every case receives penicillin to clear the organism and long-term benzathine penicillin to prevent recurrences that compound valve injury.
What you must remember
- Criteria basis: two major or one major plus two minor criteria with evidence of recent group A streptococcal infection — rising anti-streptolysin O or anti-DNase B titres, positive throat culture or rapid antigen test.
- Major criteria: carditis (clinical or subclinical on echocardiography, mitral regurgitation the classic lesion), migratory polyarthritis of large joints, Sydenham chorea, erythema marginatum and subcutaneous nodules.
- Minor criteria: fever, polyarthralgia, raised ESR or C-reactive protein, and prolonged PR interval — a major manifestation cannot double-count as a minor one.
- Special rules: chorea and indolent carditis may each justify the diagnosis alone, appearing after other findings and streptococcal markers have faded.
- Treatment of the attack: penicillin to eradicate the organism (erythromycin if allergic), aspirin or naproxen for arthritis and fever, corticosteroids for moderate-to-severe carditis, and haloperidol or sodium valproate for troublesome chorea.
- Secondary prophylaxis: benzathine penicillin G 1.2 million units intramuscularly every four weeks (600,000 units below about 27 kg), continued for years — five years or until age 21 without carditis, longer with carditis or residual valve disease.
- Echocardiography: performed in every suspected case, since subclinical carditis changes classification, counselling and prophylaxis duration.
Common confusion
Candidates blur the streptococcal syndromes: pharyngitis leads to rheumatic fever, while skin infection leads to post-streptococcal glomerulonephritis — rheumatic fever never follows skin infection. The arthritis also confuses: rheumatic arthritis is dramatically migratory, exquisitely salicylate-responsive and non-deforming, unlike septic or juvenile idiopathic arthritis. On prophylaxis, separate treating the attack (a short penicillin course to clear the organism) from preventing the next one (years of monthly benzathine penicillin) — the two decisions are tested separately.
Exam-focused takeaway
NEET-PG asks rheumatic fever as a criteria-recognition exercise: a schoolchild with recent sore throat, migratory large-joint arthritis, fever and raised ESR gives one major plus two minor with streptococcal evidence. Learn which findings stand alone (chorea, indolent carditis) and which cannot double-count. Expect one-liners on the prophylaxis drug, dose interval (every four weeks) and duration rules, mechanism questions answered by molecular mimicry, and echocardiography as the modality that upgraded carditis detection.
Frequently asked questions
What is required to diagnose acute rheumatic fever?
Two major, or one major plus two minor, Jones criteria together with evidence of preceding group A streptococcal pharyngitis, with echocardiography in every suspected case.
Which manifestation causes permanent damage?
Carditis — chiefly mitral valve regurgitation — the only criterion that leaves chronic rheumatic heart disease; the rest resolve completely.
Which streptococcal infection triggers it?
Pharyngitis due to group A beta-haemolytic streptococci; skin infection never triggers rheumatic fever, though it can trigger glomerulonephritis.
What is the secondary prophylaxis regimen?
Benzathine penicillin G 1.2 million units intramuscularly every four weeks (600,000 units for smaller children), continued for years depending on carditis and valve disease.
How is Sydenham chorea managed?
Usually observation and reassurance, since it is self-limiting; haloperidol or sodium valproate is added when movements interfere with function.
Why interpret the PR interval carefully?
Prolonged PR is only a minor criterion, cannot count when carditis is already a major criterion, and is non-specific in normal children.