Rheumatic Fever: Symptoms and the Lab Tests Behind Them

Rheumatic fever is a serious inflammatory disease that can develop after an infection with group A Streptococcus bacteria, often following a strep throat. It mainly affects children between the ages of 5 and 15, but it can also occur in adults. Understanding the symptoms and the lab tests used to diagnose rheumatic fever is important for early detection and management.

What is Rheumatic Fever?

Rheumatic fever is an inflammatory disease that can occur as a complication of untreated or inadequately treated strep throat or scarlet fever, both caused by the group A Streptococcus bacteria. The condition can cause inflammation in the heart, joints, skin, and brain. This inflammation can lead to serious complications, including rheumatic heart disease, which can damage the heart valves.

Symptoms of Rheumatic Fever

The symptoms of rheumatic fever can vary widely among individuals and may include:

• Fever: A high temperature is often one of the first signs.
• Painful and swollen joints: Especially in the knees, ankles, elbows, and wrists.
• Red, hot, or swollen skin over the affected joints.
• Small, painless bumps under the skin.
• Chest pain or palpitations: Caused by inflammation of the heart.
• Fatigue: General feeling of being unwell and tired.
• Rash: A flat or slightly raised, painless rash with a ragged edge.
• Uncontrolled movements: A condition known as Sydenham chorea, which involves jerky, uncontrollable movements of hands, feet, and face.

Lab Tests for Diagnosing Rheumatic Fever

To diagnose rheumatic fever, doctors may use a combination of clinical evaluation and lab tests. Key tests include:

• Throat Culture or Rapid Strep Test: These tests detect the presence of group A Streptococcus bacteria in the throat.
• Blood Tests: These can include:
  • Antistreptolysin O (ASO) Titer: Measures antibodies produced against streptolysin O, a substance produced by group A Streptococcus bacteria.
  • Erythrocyte Sedimentation Rate (ESR): Measures the rate at which red blood cells settle at the bottom of a test tube. A faster rate can indicate inflammation in the body.
  • C-Reactive Protein (CRP) Test: Measures the level of CRP in the blood, which rises in response to inflammation.
• Electrocardiogram (ECG or EKG): A test that records the electrical activity of the heart and can detect heart involvement.

Frequently Asked Questions

What causes rheumatic fever? Rheumatic fever is caused by an immune response to a group A Streptococcus infection, such as strep throat or scarlet fever. The body's immune system mistakenly attacks its own tissues, leading to inflammation.

Can rheumatic fever be prevented? Yes, rheumatic fever can often be prevented by promptly treating strep throat infections with antibiotics.

Is rheumatic fever contagious? Rheumatic fever itself is not contagious, but the group A Streptococcus bacteria that can lead to it is contagious and can be spread through respiratory droplets.

When to See a Doctor

If you or your child experience symptoms of strep throat, such as a sore throat, fever, or swollen lymph nodes, it is important to see a doctor. Early and effective treatment of strep throat can prevent rheumatic fever. If you or your child develop symptoms like joint pain, fever, or unusual movements, consult a healthcare provider promptly to assess the need for further testing.

Decisions about diagnosis, treatment, and management should always be made in consultation with a qualified healthcare provider.