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Acute Rheumatic Fever

  1. Rheumatic fever is an acute immunologically mediated multi-system inflammatory disease

2. Caused by:

A. Group A beta-hemolytic Streptococcal infection

B. Strains involved: M-1,3,5,6,18

3. Most commonly affected age group: 5-15 years

4. Occurrence: Females > Males

5. Occurs few weeks after an attack of Group A b-hemolytic Streptococcal Pharyngitis / Sore Throat

6. Only 3% patients with Group A streptococcal pharyngitis develop acute rheumatic fever

7. Disease is a Type II Hypersensitivity reaction

8. Pathogenesis: Molecular mimicry / Cross Reactivity

Infection by Group A b-haemolytic Streptococci


Antibodies formed against ‘M’ protein of some streptococcal strains (1, 3, 5, 6, and 18)


Cross-react with the glycoprotein antigens in the heart, joints and other tissues (called as ‘Cross Reactivity’)

Since Molecular structure of the antigen in both Host and Streptococci are similar, so called as ‘Molecular Mimicry’

9. Note: Heart Valves are affected:

A. M/C Heart valve affected: Mitral Valve. B. Least commonly affected valve: Pulmonary Valve

10. Additional info:

A. Acute Rheumatic Fever & RHD occurs secondary to only:

• Pharyngitis ✔️
• Impetigo ❌

B. PSGN (Post-Streptococcal Glomerulonephritis) occurs secondary to both:

• Pharyngitis ✔️
• Impetigo ✔️

11. The above image shows:

A. Erythema Marginatum:

• Geographical Red macular rash
• Face is generally spared
• Have a red margin & clear centre
• Becomes pale on applying pressure
• More appreciated in fair skinned individuals
• Disappears without complications
• No residual scarring

B. Subcutaneous Nodules:

• Painless swelling under skin
• Found on extensor surface of the elbows, shin & occiput

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