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Rheumatic Fever

BASICS

  • Definition: Acute rheumatic fever (ARF) is an autoimmune, inflammatory response to group A Streptococcus (GAS) infection, affecting multiple organ systems. Untreated, it can progress to chronic rheumatic heart disease (RHD).
  • Recurrence: Common without adequate antibiotic therapy.
  • Age: Most cases in children 5–15 years; rare <5 years.

EPIDEMIOLOGY

  • Endemic Regions: South Pacific, indigenous populations of Australia, New Zealand, Africa, Asia; rare in developed countries.
  • Incidence: Worldwide: 8–51/100,000 school-aged children; US: <3.4–2/100,000.
  • Prevalence: RHD affects >33 million globally.
  • Gender: Male = female; females higher risk for chorea and RHD.

ETIOLOGY & PATHOPHYSIOLOGY

  • Typical Onset: 2–3 weeks after GAS pharyngitis; also follows GAS impetigo.
  • Pathogenesis: Immune cross-reactivity (molecular mimicry) triggers inflammation affecting joints, heart, CNS, skin.
  • Genetics: Polygenic, variable penetrance; some populations at higher risk.

RISK FACTORS

  • Poverty, crowding, social disadvantage, genetic susceptibility, certain ethnic groups.

PREVENTION

  • Primary: Timely antibiotic treatment of strep infection.
  • Secondary: Long-term antibiotic prophylaxis (5–10 years) to prevent recurrence.

DIAGNOSIS

  • Jones Criteria (2015 update):
  • Initial: 2 major or 1 major + 2 minor
  • Recurrent: 2 major, or 1 major + 2 minor, or 3 minor
  • Sydenham chorea is sufficient for diagnosis (even without lab evidence).
  • Major (Low-Risk): Carditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules.
  • Minor (Low-Risk): Polyarthralgia, fever ≥38.5°C, ESR ≥60, CRP ≥3 mg/dL, ↑PR interval.
  • Major (Moderate/High-Risk): Carditis, polyarthritis/monoarthritis, chorea, erythema marginatum, subcutaneous nodules.
  • Minor (Moderate/High-Risk): Monoarthralgia, fever ≥38°C, ESR ≥30, CRP ≥3, ↑PR interval.
  • Evidence of Preceding GAS Infection: Rapid strep, throat culture, rising ASO/ADB titers (ASO peaks 3–5 wks; ADB 6–8 wks post-infection).

HISTORY & PHYSICAL EXAM

  • Typical Presentation: 2–3 weeks post-GAS infection (pharyngitis/impetigo).
  • Polyarthritis: Migratory, affects large joints, self-limited.
  • Carditis: May be subclinical (echo) or manifest as murmur, pericardial rub, heart failure.
  • Sydenham chorea: Late (1–6 months post-infection); involuntary movements, psychiatric symptoms; self-resolves.
  • Skin Findings:
  • Erythema marginatum: Evanescent, pink rash, nonpruritic, blanches, on trunk/proximal limbs.
  • Subcutaneous nodules: Firm, painless, on extensor surfaces.

DIFFERENTIAL DIAGNOSIS

  • SLE, post-strep reactive arthritis, juvenile rheumatoid arthritis, myocarditis, Kawasaki disease, PANDAS, Lyme, infectious arthritis, Tourette, encephalitis, others.

DIAGNOSTIC TESTS

  • Labs: Rapid strep, throat culture, ASO/ADB titers, CBC (leukocytosis, normocytic anemia), ESR/CRP elevated.
  • ECG: PR prolongation, AV block, pericarditis signs.
  • Echo: Mitral/aortic regurgitation, chamber enlargement, pericardial effusion. All ARF cases should have echo within 12 weeks.
  • Joint aspiration if septic arthritis suspected.

TREATMENT

General Measures

  • Antibiotics to eradicate GAS
  • Anti-inflammatories (naproxen preferred over aspirin)
  • Manage manifestations: heart failure, chorea, etc.

Medications

  • GAS Eradication:
  • First line (no allergy): Penicillin VK 250 mg PO BID ×10d, benzathine penicillin G IM ×1, or amoxicillin 50 mg/kg ×10d
  • Allergy: 1st-gen cephalosporin ×10d, azithromycin ×5d, clindamycin ×10d, or clarithromycin ×10d
  • Arthritis: Naproxen 10–20 mg/kg/day divided BID; NSAIDs (avoid aspirin if possible in children due to Reye risk).
  • Carditis: Supportive, treat heart failure if present.
  • Chorea: Usually self-limited; severe: valproic acid/carbamazepine; IVIG/steroids if refractory.

Secondary Prophylaxis

  • Duration:
  • No carditis: Until age 21 or 5 years after diagnosis (whichever later)
  • With carditis: Until age 21 or 10 years after diagnosis (whichever later)
  • With valvular disease: May require indefinite prophylaxis
  • Regimens:
  • Benzathine penicillin G IM monthly (preferred)
  • Penicillin V PO 250 mg BID (alternative)
  • Sulfadiazine if penicillin allergic; azithromycin if allergic to both
  • Clindamycin for breakthrough GAS pharyngitis on prophylaxis

ISSUES FOR REFERRAL

  • Cardiologist: ARF management and RHD surveillance
  • Pediatric neurologist for severe chorea

SURGERY

  • For late sequelae, e.g., valve stenosis from fibrosis/calcification

ADMISSION/INPATIENT CARE

  • For diagnostic clarification or heart failure.
  • IV fluids (cautious in heart failure), activity as tolerated.

ONGOING CARE

  • Follow-up: Weekly initially, then every 6 months if stable.
  • Repeat echocardiograms to monitor for cardiac involvement, even if initial echo is normal.
  • Screen household contacts for GAS.
  • Education: Avoid Reye syndrome (aspirin caution), importance of adherence.

PROGNOSIS

  • Depends on cardiac involvement severity. Recurrences most likely within first year.
  • RHD may develop 10–20 years post-ARF, especially mitral valve.
  • Heart failure is most severe complication.

COMPLICATIONS

  • RHD (mitral/aortic valve disease)
  • Heart failure
  • Infective endocarditis risk
  • Chronic arthropathy (Jaccoud)
  • Recurrence with GAS reinfection

ICD-10 CODES

  • I00: Rheumatic fever without heart involvement
  • I01.9: Acute rheumatic heart disease, unspecified
  • I01.0: Acute rheumatic pericarditis

CLINICAL PEARLS

  • ARF is an autoimmune sequela of GAS infection, affecting heart, joints, CNS, skin.
  • Modified Jones criteria guide diagnosis (low vs. moderate/high risk).
  • Early echocardiography can detect subclinical carditis, improving outcomes.
  • Treatment: Eradicate GAS (ideally within 9 days), then initiate long-term antibiotic prophylaxis. NSAIDs (naproxen preferred) for arthritis.