Acute Rheumatic Fever: Symptoms, Diagnosis, Treatment & Prevention Guide

Acute Rheumatic Fever: What Is It?

An autoimmune inflammatory condition known as acute rheumatic fever (ARF) appears two to four weeks after untreated Group A Streptococcal (GAS) pharyngitis. The illness causes an aberrant immune response that impacts the brain, heart, joints, skin, and subcutaneous tissues.

Key Fact: ARF only follows throat infections caused by Streptococcus pyogenes. Streptococcal skin infections like impetigo do not cause rheumatic fever, though they can lead to post-streptococcal glomerulonephritis.

Children in low- and middle-income countries in South Asia, Sub-Saharan Africa, and indigenous populations in Australia and New Zealand are disproportionately affected by the disease, which is still a major cause of avoidable cardiovascular morbidity worldwide.

What Causes Acute Rheumatic Fever?

The underlying mechanism involves molecular mimicry. The streptococcal M protein shares structural similarities with human cardiac tissue, joint synovium, and brain neurons. When the immune system attacks streptococcal antigens, antibodies and T-cells cross-react with the body's own tissues.

This autoimmune response affects:

• Heart valves and cardiac myosin → rheumatic carditis
• Basal ganglia neurons → Sydenham chorea
• Joint synovium → migratory arthritis

The Aschoff body is the pathognomonic histological finding in rheumatic carditis, containing characteristic Anitschkow cells with "caterpillar" or "owl-eye" nuclei surrounding areas of fibrinoid necrosis.

Acute Rheumatic Fever: Who Can Get It? Epidemiology and Risk Factors

School-age children between the ages of five and fifteen are most commonly affected by ARF. Before the age of three, the condition is rare; after the age of twenty-five, it is uncommon. Among the risk factors are:

• Prior ARF episode (significantly raises the risk of recurrence)
• Living conditions that are too crowded
• restricted access to healthcare
• Endemic areas with a high incidence of GAS

Important: Before developing ARF, up to one-third of patients do not remember having a sore throat. The first episode of pharyngitis could be minor, subclinical, or just forgotten.

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What Are the Symptoms of Acute Rheumatic Fever?

ARF presents with a constellation of major and minor manifestations defined by the Jones criteria. Symptoms typically appear 2-4 weeks after a streptococcal throat infection.

Major Manifestations

1. Rheumatic Carditis (50-70% of cases)

Carditis is the most serious manifestation because it's the only one causing permanent damage. Clinical features include:

• The most frequently affected valve in valvulitis is the mitral valve (mitral regurgitation), which is followed by the aortic valve.
• Typical murmurs include the apical pansystolic murmur (mitral regurgitation), the mid-diastolic Carey Coombs murmur, and the early diastolic murmur at the left sternal border (aortic regurgitation).
• Heart failure symptoms include dyspnea, cardiomegaly, and tachycardia.
• Chest pain and friction rub are symptoms of pericarditis, which is always associated with valvulitis.

Crucial Point: Without valvulitis, rheumatic carditis cannot be diagnosed. A different diagnosis is suggested by isolated myocarditis or pericarditis without valve involvement.

2. 60–75% of cases of migratory polyarthritis

Rheumatic arthritis is characterized by:

• Inflammation migrates from one joint to another.
• Large joint involvement: wrists, elbows, ankles, and knees
• Severe pain: Frequently out of proportion to obvious swelling
• Significant improvement within 24 to 48 hours is a dramatic NSAID response.
• No long-term harm: resolves entirely without causing joint destruction

3. Sydenham Chorea (10–30% of cases)

Chorea, also known as St. Vitus Dance, is characterized by involuntary, aimless, non-rhythmic movements of the limbs, face, and trunk. Traditional signs consist of:

• Milkmaid's grip: Squeezing the examiner's fingers irregularly
• Pronator sign: Propensity to pronate hands that are extended and supinated
• Darting tongue: Unable to maintain a steady tongue protrusion
• Deteriorating handwriting
• Lability on an emotional level
• Emotional lability

Unique Feature: Chorea can appear in isolation 1-6 months after streptococcal infection when ASO titres may have normalised, and other manifestations are absent.

4. Erythema Marginatum (<5% of cases)

This distinctive but rare rash features:

• Erythematous, non-pruritic, serpiginous (snake-like) lesions
• Raised margins with clear centres
• Trunk and proximal limbs (spare face)
• Evanescent appearance—comes and goes over hours
• Enhanced by warmth

5. Subcutaneous Nodules (<5% of cases)

Firm, painless nodules (0.5-2 cm) over bony prominences and extensor surfaces. These almost always indicate severe carditis.

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How Can Acute Rheumatic Fever Be Identified? Jones Criteria (2015)

The diagnostic standard is still the updated Jones criteria from 2015. The update acknowledged subclinical carditis and established population-specific thresholds.

Verifying Previous GAS Infection

It is necessary to have at least one of the following:

• GAS-positive throat culture
• Rapid antigen detection test (RADT) result: positive
• Streptococcal antibody titres (ASO, anti-DNase B) that are elevated or increasing

Clinical Advice: For optimal sensitivity, test both anti-DNase B and ASO. By the time ARF manifests, throat cultures are frequently negative.

Thresholds for Diagnostics

Low-Risk Populations (incidence of ARF ≤2 per 100,000 children of school age):

• two main requirements, OR
• One major and two minor requirements

Populations at Moderate to High Risk, such as those in Africa, the Pacific Islands, and India:

• two main requirements, OR
• One major plus two minor requirements, OR
• Three minor requirements (added for populations at high risk)

2015 Updates: What Changed?

Exemptions from the Jones Criteria

ARF can be diagnosed in three situations without fulfilling all requirements:

1. When other causes are ruled out, isolated chorea is sufficient (GAS evidence may be absent).
2. Indolent carditis: Rheumatic valve disease that manifests late
3. Recurrent ARF: Patients with documented prior ARF/RHD require fewer criteria.

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What Investigations Are Required?

Crucial Examinations

Essential Tests

• Streptococcal antibodies: ASO and anti-DNase B (test both)
• Inflammatory markers: ESR, CRP, complete blood count
• ECG: PR interval prolongation (30-40% of cases)
• Echocardiography: Mandatory for all suspected ARF—detects subclinical carditis in up to 20%
• Chest X-ray: If heart failure is suspected

How Is Acute Rheumatic Fever Treated?

Step 1: GAS Eradication

Administer antibiotics regardless of throat culture results:

First-line: Benzathine Penicillin G (single IM injection)

• <27 kg: 600,000 units
• ≥27 kg: 1.2 million units

Oral erythromycin or azithromycin for ten days if you have a penicillin allergy

Step 2: Treatment for Inflammation

Carditis-free arthritis:

• Aspirin 80–100 mg/kg daily in four to five separate doses
• Continue until the inflammatory markers return to normal and the symptoms go away.
• Naproxen 10–20 mg/kg/day is an alternative.

Heart failure and carditis:

• For two to three weeks, take 1-2 mg/kg of prednisone daily (maximum 60–80 mg/day).
• To avoid rebound, taper while taking aspirin concurrently.
• When necessary, standard heart failure management

Step 3: Management of Chorea

• Rest and less stimulation in mild cases
• Moderate-to-severe: haloperidol, valproic acid, or carbamazepine
• Self-limited condition; only symptoms are treated with medication

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How Long Should Secondary Prophylaxis Continue?

Secondary prophylaxis is the cornerstone of long-term management. Each ARF episode causes cumulative cardiac damage.

Drug of Choice

Benzathine Penicillin G (IM)

• <27 kg: 600,000 units every 3-4 weeks
• ≥27 kg: 1.2 million units every 3-4 weeks

Every 3 weeks is preferred in high-risk populations for better protection.

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Duration Guidelines

What Is the Prognosis of Acute Rheumatic Fever?

• Arthritis: Resolves completely without sequelae
• Chorea: No long-term neurological impairment; self-limited over weeks to months
• Carditis: Results vary; mild cases may go away, while moderate-to-severe cases frequently develop into chronic rheumatic heart disease (RHD).

Rheumatic Heart Disease Progression

Over time, chronic scarring from mitral regurgitation may progress to mitral stenosis. Heart failure, atrial fibrillation, the risk of infective endocarditis, and stroke are complications that may necessitate valve replacement or repair. Common Questions Regarding Acute Rheumatic Fever

Mitral regurgitation can evolve into mitral stenosis over the years through chronic scarring. Complications include heart failure, atrial fibrillation, infective endocarditis risk, and stroke—potentially requiring valve repair or replacement.

Frequently Asked Questions About Acute Rheumatic Fever

Is it possible to have rheumatic fever without having a sore throat?

Indeed. A third or more of ARF patients do not remember having had pharyngitis in the past. It's possible that the throat infection was minor, showed no symptoms, or was just forgotten. Because of this, laboratory evidence—such as elevated streptococcal antibodies—is more trustworthy than clinical history.

Subclinical carditis: what is it?

Echocardiographic evidence of mitral or aortic regurgitation without an audible murmur is referred to as subclinical carditis. Echocardiography is now required for all suspected cases because studies reveal that 15–20% of ARF patients have valve involvement that can only be detected by this method.

What distinguishes ARF from post-streptococcal reactive arthritis?

Although it does not fit the Jones criteria, post-streptococcal reactive arthritis (PSRA) occurs after GAS infection. The arthritis is usually symmetrical, may affect the axial skeleton and small joints, does not follow the traditional migratory pattern, and reacts poorly to aspirin. Many experts advise prophylaxis for PSRA patients as well because some of them develop carditis during follow-up.

Why is the recommended benzathine penicillin interval three weeks?

Penicillin levels may fall below protective thresholds in some people within four weeks, according to studies conducted in high-risk populations. For the duration of the prophylactic period, the 3-week interval ensures sufficient coverage.

Is chorea the sole sign of rheumatic fever? Indeed. After ASO titres have returned to normal and other symptoms have subsided, chorea may manifest one to six months after a streptococcal infection.

Yes. Chorea can appear 1-6 months after streptococcal infection when ASO titres have normalised, and other manifestations have resolved. In endemic areas, isolated chorea without an alternative explanation is presumed rheumatic and requires secondary prophylaxis.

Important Lessons

• ARF does not result from skin infections; it occurs two to four weeks after GAS pharyngitis.
• Jones criteria 2015 reduced thresholds for high-risk groups and included subclinical carditis as a key criterion.
• Echocardiography is required and can identify up to 20% of cases of subclinical carditis.
• Isolated pericarditis or myocarditis is not rheumatic carditis; carditis is equivalent to valvulitis.
• Benzathine penicillin, administered every three weeks as a secondary prophylactic, stops heart damage from progressing and recurring.
• Early diagnosis and consistent prophylaxis can prevent a lifetime of rheumatic heart disease

This article is for educational purposes. Always consult qualified healthcare professionals for diagnosis and treatment decisions.