Acute rheumatic fever management ,criterion , pathophysiology, etiology , investigation Answer in brief , give flowchart ,and table answer as short answer question

Reading File

Finding Sources

Reading File

Finding Sources

Reading File

Finding Sources

Reading File

I now have comprehensive data. Let me compose the full answer.

Acute Rheumatic Fever (ARF) - Short Answer Guide

1. ETIOLOGY

Causative agent: Group A beta-hemolytic Streptococcus (GAS) - Streptococcus pyogenes - pharyngeal infection (and increasingly, skin infection in endemic regions).

Rheumatogenic M-serotypes: 1, 3, 5, 6, 14, 18, 19, 24, 27, 29 (many more now recognised).

Key facts:

Only ~3-6% of any population is genetically susceptible to ARF after GAS infection
HLA class II allele polymorphisms and TNF/mannose-binding lectin variants confer susceptibility
44% concordance in monozygotic twins (vs 12% dizygotic) - confirms strong genetic component
Occurs most in children aged 5-14 years; recurrences remain common into young adulthood

Source: Harrison's Principles of Internal Medicine 22E, Goldman-Cecil Medicine

2. PATHOPHYSIOLOGY

Flowchart

GAS Pharyngitis / Skin Infection
          ↓
 M-protein antigens processed by
   innate immune antigen-presenting cells
          ↓
   T-cell activation (humoral + cellular)
          ↓
  MOLECULAR MIMICRY
  (Streptococcal antigens mimic human proteins)
          ↓
Cross-reactive antibodies bind cardiac endothelium
→ VCAM-1 upregulation → lymphocyte recruitment
→ Endothelial lysis + complement activation
→ Release of laminin, keratin, tropomyosin peptides
          ↓
  Cross-reactive T cells invade heart
  (epitope spreading amplifies damage)
          ↓
 ┌─────────────────────────────────────────┐
 │         TISSUE INJURY BY LOCATION       │
 ├──────────────┬──────────────────────────┤
 │ Heart        │ Antibody binding +        │
 │              │ T-cell infiltration       │
 │              │ → CARDITIS (pancarditis)  │
 ├──────────────┼──────────────────────────┤
 │ Joints       │ Immune complexes          │
 │              │ → ARTHRITIS               │
 ├──────────────┼──────────────────────────┤
 │ Basal ganglia│ Antibody binding          │
 │              │ → CHOREA                  │
 ├──────────────┼──────────────────────────┤
 │ Skin/SC      │ Delayed hypersensitivity  │
 │              │ → Erythema marginatum,    │
 │              │   Subcutaneous nodules    │
 └──────────────┴──────────────────────────┘

Latent period: ~3 weeks (range 1-5 weeks) after pharyngitis; chorea/indolent carditis may appear up to 6 months later.

Source: Harrison's 22E, Goldman-Cecil Medicine

3. REVISED JONES CRITERIA (2015 AHA Update)

Requires: Evidence of preceding GAS infection PLUS fulfillment of criteria below

Diagnostic Rule

Presentation	Requirement
Initial ARF	2 major OR 1 major + 2 minor
Recurrent ARF	2 major OR 1 major + 2 minor OR 3 minor

Major Criteria

Criterion	Low-Risk Population	Moderate/High-Risk Population
Carditis	Clinical and/or subclinical (echo)	Clinical and/or subclinical (echo)
Arthritis	Polyarthritis only	Monoarthritis OR polyarthritis; polyarthralgia also counts
Chorea	✓	✓
Erythema marginatum	✓	✓
Subcutaneous nodules	✓	✓

Minor Criteria

Criterion	Low-Risk	Moderate/High-Risk
Arthralgia	Polyarthralgia	Monoarthralgia
Fever	≥38.5°C	≥38°C
ESR	≥60 mm/h	≥30 mm/h
CRP	≥3.0 mg/dL	≥3.0 mg/dL
Prolonged PR interval	✓ (unless carditis is major criterion)	✓ (unless carditis is major criterion)

Low-risk: ARF incidence <2/100,000 school-age children/year OR RHD prevalence ≤1/1000/year

4. CLINICAL FEATURES (Frequency)

Feature	Frequency
Fever	>90%
Migratory polyarthritis	60-75%
Carditis (pancarditis)	50-75%
Chorea (Sydenham's)	2-30% (varies by population)
Erythema marginatum	<5-10%
Subcutaneous nodules	<5-10%

Carditis note: Mitral valve almost always affected; aortic valve in 20-30%. Mitral regurgitation is the hallmark early lesion.

Chorea note: Involuntary, non-rhythmic, purposeless movements; stops during sleep; asymmetric ("Sydenham chorea / St. Vitus dance").

5. INVESTIGATIONS

Flowchart

Suspected ARF
      ↓
┌─────────────────────────────────────────┐
│  CONFIRM GAS INFECTION                  │
│  • Throat swab culture                  │
│  • Anti-streptolysin O (ASO) titre      │
│  • Anti-DNase B (ADB) titre             │
│  • Rapid strep antigen test             │
└────────────────┬────────────────────────┘
                 ↓
┌─────────────────────────────────────────┐
│  ACUTE PHASE REACTANTS / INFLAMMATION   │
│  • ESR                                  │
│  • CRP                                  │
│  • CBC (leukocytosis, normocytic anemia)│
└────────────────┬────────────────────────┘
                 ↓
┌─────────────────────────────────────────┐
│  CARDIAC INVESTIGATIONS                 │
│  • ECG → prolonged PR interval          │
│  • Echocardiogram → valvulitis,         │
│    subclinical carditis, regurgitation  │
└────────────────┬────────────────────────┘
                 ↓
┌─────────────────────────────────────────┐
│  EXCLUDE ALTERNATIVES (as indicated)   │
│  • ANA, dsDNA, anti-CCP (reactive       │
│    arthritis, lupus, JIA)               │
│  • Blood cultures (septic arthritis)    │
│  • Synovial fluid aspirate              │
│  • Gonorrhoeae / Chlamydia PCR          │
│  • Viral serology (parvovirus B19,      │
│    CMV, hepatitis)                      │
│  • Pregnancy test                       │
│  • UEC / creatinine (before NSAIDs)     │
└─────────────────────────────────────────┘

6. MANAGEMENT

Flowchart

CONFIRMED ARF
      ↓
 HOSPITALIZE + BED REST
      ↓
┌───────────────────────────────────────────────┐
│  STEP 1: ERADICATE GAS                        │
│  • Benzathine penicillin G IM:                │
│    - ≤27 kg: 600,000 units single dose        │
│    - >27 kg: 1.2 million units single dose    │
│  • OR Oral penicillin V 500 mg BD x 10 days   │
│  • OR Amoxicillin 50 mg/kg/day x 10 days      │
│  • Penicillin allergy: Azithromycin/macrolide  │
└───────────────────────┬───────────────────────┘
                        ↓
┌───────────────────────────────────────────────┐
│  STEP 2: TREAT MANIFESTATIONS                 │
│                                               │
│  ARTHRITIS / FEVER:                           │
│  • Aspirin 50-100 mg/kg/day in 4-5 doses      │
│    (max 4-8 g/day) x 2-4 weeks                │
│  • OR Naproxen 10-20 mg/kg/day BD             │
│    (preferred - safer, less GI side effects)  │
│                                               │
│  CARDITIS (mild-moderate):                    │
│  • Treat heart failure: diuretics,            │
│    ARBs, fluid restriction, bed rest          │
│                                               │
│  CARDITIS (severe):                           │
│  • ± Corticosteroids (prednisolone)           │
│    [limited evidence; used empirically]       │
│                                               │
│  CHOREA:                                      │
│  • Usually self-limiting (weeks-months)       │
│  • Carbamazepine or haloperidol if severe     │
│  • IVIg only for refractory severe chorea     │
└───────────────────────┬───────────────────────┘
                        ↓
┌───────────────────────────────────────────────┐
│  STEP 3: SECONDARY PROPHYLAXIS                │
│  • Benzathine penicillin G 1.2 million units  │
│    (600,000 units if ≤27 kg) IM every 4 weeks │
│  • Duration (see table below)                 │
└───────────────────────────────────────────────┘

Secondary Prophylaxis Duration Table

Category	Duration
ARF without carditis	5 years or until age 21 (whichever is longer)
ARF with mild/resolved carditis	10 years or until age 21
Persistent RHD (mild-moderate)	10 years or until age 40
Severe RHD / post-valve surgery	Lifelong

Oral alternatives: Penicillin V 250 mg BD or erythromycin 250 mg BD (penicillin allergy)

Management Summary Table

Problem	Treatment
GAS eradication	Benzathine pen G IM single dose
Arthritis/fever	Aspirin or Naproxen
Carditis/heart failure	Diuretics + ARBs ± steroids
Chorea	Carbamazepine/haloperidol; self-limiting
Secondary prevention	Benzathine pen G IM q4 weeks

Key Mnemonics

Major criteria - "CASES":

Carditis
Arthritis (migratory)
Sydenham's chorea
Erythema marginatum
Subcutaneous nodules

Minor criteria - "LEAP":

Long PR interval
Elevated ESR/CRP
Arthralgia
Pyrexia (fever ≥38.5°C)

Sources: Harrison's Principles of Internal Medicine 22E, Goldman-Cecil Medicine, Tintinalli's Emergency Medicine, Rheumatology 2-Volume Set (Elsevier 2022)

This is a shared conversation. Sign in to Orris to start your own chat.