Although there's no single test for rheumatic fever, diagnosis is based on medical history, physical exam and certain test results.
If your child was already diagnosed with a strep infection, your doctor might not order additional tests for the bacterium. If your doctor orders a test, it will most likely be a blood test that can detect antibodies to the strep bacterium circulating in the blood. The actual bacterium might no longer be detectable in your child's throat tissues or blood.
Your doctor also is likely to check for inflammation in your child's blood by measuring C-reactive protein and the erythrocyte sedimentation rate.
Electrocardiogram (ECG or EKG)
This test — also called an ECG or EKG — records electrical signals as they travel through your child's heart. Your doctor can look for patterns among these signals that indicate inflammation of the heart or poor heart function.
Using sound waves to produce live-action images of the heart, this test can enable your doctor to detect heart abnormalities.