Rheumatic fever is caused by an infection with Streptococcal bacteria. This bacteria is responsible for strep throat infections. For some reason, after the Streptococcal infection, the immune system mistakenly attacks normal tissue. Inflammation occurs in multiple areas of the body, including the joints, heart, skin, and central nervous system.

Some cases of rheumatic fever can lead to rheumatic heart disease. In this case, damage to the heart valves leads to gradually worsening valve function. This may result in aortic stenosis, aortic regurgitation, mitral stenosis, or mitral regurgitation. A similar process can occur in the kidneys, which may lead to kidney disease or kidney failure.