Rheumatic Fever PDF

**Rheumatic Fever** **Definition** - **Rheumatic fever** is an autoimmune process following infection with group A β-hemolytic streptococcus (GAS), commonly referred to as *Streptococcus pyogenes*. - Typically follows an acute tonsillitis or pharyngitis (commonly called \"...

**Rheumatic Fever** **Definition** - **Rheumatic fever** is an autoimmune process following infection with group A β-hemolytic streptococcus (GAS), commonly referred to as *Streptococcus pyogenes*. - Typically follows an acute tonsillitis or pharyngitis (commonly called \"strep throat\"). - **GAS skin infections** (e.g., erysipelas, impetigo, cellulitis) are more often associated with poststreptococcal glomerulonephritis rather than rheumatic fever. **Overview** - **Type II hypersensitivity reaction**: Rheumatic fever is categorized as a type II hypersensitivity reaction due to molecular mimicry. - The process usually involves untreated GAS pharyngitis/tonsillitis, leading to antibody formation against the M protein of GAS. - **Molecular mimicry**: Antibodies generated against GAS cross-react with myocardial and neuronal proteins, especially myosins, resulting in an autoimmune inflammatory response that targets these tissues. - **Myocarditis**: The most common cause of death during the acute phase of rheumatic fever due to severe inflammation of the myocardium. **Diagnosis** Diagnosis of rheumatic fever requires: 1. **Evidence of recent streptococcal infection** with: - 2 major criteria, or - 1 major and 2 minor criteria. 2. **Evidence of recent streptococcal infection** may include: - Antistreptolysin O titre (ASOT) \> 200 IU/mL. - History of scarlet fever. - Positive throat swab. - Elevated DNase B titre. **Jones Criteria** **Major Criteria**: *J(heart)NES* - **Joints** -- Polyarthritis - **Heart** -- Carditis (can include endocarditis, myocarditis, or pericarditis) - **Nodules** -- Subcutaneous nodules - **Erythema marginatum** - **Sydenham\'s chorea** **Detailed Criteria**: - **Major Criteria**: 1. **Erythema marginatum**: A characteristic, non-itchy rash with pink rings on the trunk and limbs. 2. **Sydenham\'s chorea**: Involuntary, rapid movements affecting the face, hands, and feet. 3. **Polyarthritis**: Migratory inflammation of large joints, usually the knees, ankles, elbows, and wrists. 4. **Carditis**: May present as endocarditis, myocarditis, or pericarditis. 5. **Subcutaneous nodules**: Pea-sized, firm, and non-tender, commonly found on the extensor surfaces of joints (e.g., knees, elbows) and over the spine. - **Minor Criteria**: 6. Elevated inflammatory markers (ESR or CRP). 7. Fever (pyrexia). 8. Arthralgia (if arthritis is not included as a major criterion). 9. Prolonged PR interval on ECG. **Histology** - **Aschoff bodies**: Pathognomonic foci of chronic inflammation within the myocardium in acute rheumatic fever. - **Anitschkow cells**: Reactive histiocytes with distinctive wavy, caterpillar-like nuclei within Aschoff bodies, indicating acute rheumatic myocarditis. **Management** - **Bed Rest**: Recommended until CRP levels remain normal for two consecutive weeks (sometimes up to 3 months). - **Antibiotic Therapy**: - **Benzylpenicillin**: 0.6--1.2 g IV initially, followed by **phenoxymethylpenicillin** 250--500 mg PO four times daily for 10 days. - For penicillin-allergic patients, substitute with **erythromycin** or **azithromycin** for 10 days. - **Analgesia for Carditis/Arthritis**: - **Aspirin**: 100 mg/kg/day PO in divided doses (maximum 4--8 g/day) for the first 2 days, then 70 mg/kg/day for 6 weeks. Monitor salicylate levels as toxicity can lead to tinnitus, hyperventilation, and metabolic acidosis. Avoid aspirin in children due to Reye syndrome risk; use NSAIDs as an alternative. - **Prednisolone**: Added if moderate-to-severe carditis is present (signs include cardiomegaly, congestive heart failure, or third-degree heart block). - **Joint Immobilization**: For severe arthritis to minimize discomfort. - **Chorea Management**: Haloperidol (0.5 mg every 8 hours PO) or diazepam for symptomatic relief. **Prognosis** - **Chronic Rheumatic Heart Disease**: Up to 60% of patients with carditis develop chronic valvular heart disease, with severity correlating with the initial degree of carditis. - Acute rheumatic episodes typically last around 3 months, with recurrence risk triggered by subsequent streptococcal infections, pregnancy, or oral contraceptive use. - **Valve Involvement**: - Mitral valve (70%) most commonly affected. - Aortic valve (40%) and, less commonly, tricuspid (10%) and pulmonary valves (2%). - Acute attacks may cause valvular regurgitation, with stenosis developing over years. **Secondary Prophylaxis** - **Penicillin V**: 250 mg PO twice daily as a preventive measure. - **Alternative**: Sulfadiazine 1 g daily (or 0.5 g if \