Investigation Of Rheumatic Fever

Rheumatic fever is a serious inflammatory disease that can develop as a complication of untreated or poorly treated streptococcal throat infection, commonly known as strep throat. It primarily affects children and young adults and can lead to lasting damage to the heart, joints, skin, and brain if not properly diagnosed and managed. The investigation of rheumatic fever involves a careful clinical evaluation combined with laboratory tests and imaging to confirm the diagnosis and assess the severity of organ involvement. Early and accurate diagnosis is crucial to prevent chronic complications such as rheumatic heart disease, which remains a significant health problem in many parts of the world.

Understanding Rheumatic Fever

Rheumatic fever occurs after an infection by Group A Streptococcus bacteria, usually following a sore throat or pharyngitis. It is an autoimmune response where the body’s immune system mistakenly attacks its own tissues, particularly affecting the heart valves, joints, skin, and central nervous system. The condition typically develops two to four weeks after the initial infection and presents with a range of symptoms that can vary widely among patients.

Common Symptoms and Signs

Recognizing the symptoms of rheumatic fever is essential for timely investigation. Key clinical features include

• Fever and general malaise
• Migratory polyarthritis, especially involving large joints such as knees, ankles, elbows, and wrists
• Carditis, which may manifest as chest pain, shortness of breath, or heart murmur
• Sydenham chorea, characterized by involuntary, jerky movements mostly affecting the face and limbs
• Skin manifestations like erythema marginatum a distinctive rash with red edges and subcutaneous nodules

Clinical Evaluation and History Taking

The first step in the investigation of rheumatic fever involves a thorough clinical history and physical examination. A history of recent sore throat or streptococcal infection is often a critical clue. The clinician will also assess for the presence of major and minor Jones criteria, which are standardized clinical markers used worldwide to support diagnosis.

Jones Criteria for Diagnosis

The Jones criteria classify symptoms into major and minor groups, and the diagnosis of rheumatic fever requires the presence of either two major criteria or one major plus two minor criteria, along with evidence of a preceding streptococcal infection.

• Major criteriacarditis, polyarthritis, chorea, erythema marginatum, subcutaneous nodules
• Minor criteriafever, arthralgia (joint pain without swelling), elevated inflammatory markers, prolonged PR interval on electrocardiogram

Laboratory Investigations

Laboratory tests play an important role in confirming the diagnosis and excluding other conditions with similar symptoms. Key investigations include

Throat Swab and Culture

A throat swab is taken to detect the presence of Group A Streptococcus bacteria. However, a negative throat culture does not exclude rheumatic fever because the infection might have resolved by the time symptoms appear.

Blood Tests

• Antistreptolysin O (ASO) titerElevated ASO levels indicate a recent streptococcal infection.
• C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR)These are markers of inflammation and are typically raised during an active episode of rheumatic fever.
• Complete blood count (CBC)May show mild anemia or elevated white blood cells.

Cardiac Evaluation

Since rheumatic fever often affects the heart, thorough cardiac assessment is necessary to detect carditis or valvular damage early on.

Physical Examination

The doctor listens for heart murmurs, which may suggest inflammation of the heart valves or other cardiac involvement.

Electrocardiogram (ECG)

An ECG helps identify abnormalities such as prolonged PR interval, which is considered a minor Jones criterion and may indicate conduction system involvement.

Echocardiography

Echocardiography (heart ultrasound) is an essential non-invasive tool used to visualize heart structures and function. It helps detect inflammation, valve regurgitation, and any early signs of rheumatic heart disease that may not yet be audible through a stethoscope.

Differential Diagnosis

Investigating rheumatic fever involves ruling out other conditions with overlapping symptoms. These may include

• Juvenile idiopathic arthritis or other inflammatory joint diseases
• Infective endocarditis
• Lupus erythematosus and other autoimmune diseases
• Post-streptococcal glomerulonephritis
• Neurological disorders causing chorea

Treatment and Follow-Up

Once rheumatic fever is diagnosed, treatment focuses on eradicating any remaining streptococcal bacteria, reducing inflammation, and managing symptoms. Penicillin remains the antibiotic of choice for treating streptococcal infection and for long-term prophylaxis to prevent recurrence. Anti-inflammatory medications like aspirin or corticosteroids may be prescribed to control joint and heart inflammation.

Regular follow-up with clinical and echocardiographic monitoring is important to detect progression to chronic rheumatic heart disease. Early intervention can significantly improve patient outcomes and reduce complications.

The investigation of rheumatic fever requires a comprehensive approach combining clinical assessment, laboratory tests, and imaging studies. Awareness of typical symptoms, understanding diagnostic criteria such as the Jones criteria, and timely use of investigations help ensure accurate diagnosis and effective management. Despite being preventable and treatable, rheumatic fever continues to pose challenges, especially in resource-limited settings. Therefore, improving early detection and treatment remains a priority in global health efforts to reduce the burden of this potentially debilitating disease.