Acute Rheumatic Fever (ARF)
ARF is an autoimmune sequela of group A streptococcal (GAS) pharyngitis. Diagnosis is established using the modified Jones criteria, requiring evidence of a preceding GAS infection plus two major or one major and two minor criteria.
1. Major Criteria (JONES)
- Joint: Migratory polyarthritis.
- O (Carditis): Pancarditis (endocarditis, myocarditis, pericarditis).
- Nodules: Subcutaneous nodules.
- Erythema marginatum: Characteristic rash.
- Sydenham chorea: Delayed involuntary movements.
2. Minor Criteria
| Clinical | Laboratory |
|---|---|
| Fever | Elevated ESR or CRP |
| Arthralgia | Prolonged PR interval on ECG |
3. Evidence of Preceding GAS Infection
- Positive rapid antigen test or throat culture.
- Elevated or rising anti-streptolysin O (ASO) titer or other anti-streptococcal antibodies.
NEET PG Hint: Remember that Carditis is the only major criterion that can be considered a stand-alone diagnosis (in limited specific presentations), and Sydenham chorea is often a late manifestation occurring months after the initial infection. Always perform an echocardiogram to confirm subclinical carditis.