Rheumatic fever is often caused by an untreated infection of strep throat, which causes a very sore throat and a fever of more than 100 degrees (37.8 degrees Celsius). Researchers estimate that about three percent of untreated cases of strep throat will develop into rheumatic fever.

The first symptoms of rheumatic fever tend to occur between one and six weeks after the initial infection, but some symptoms may not appear until six months later. Depending on the individual and the severity of the condition, these symptoms may include:

Signs of the condition that may be identified by a physician include:

• Carditis. Approximately 50 percent of patients with rheumatic fever exhibit this swelling of the heart walls. Damage to a valve and/or chordae, which attach the valve to the heart wall, will mostly affect the mitral valve or aortic valve.

• Chorea. Occurring in about 20 percent of cases, chorea is a rheumatic inflammation in the central nervous system. This condition, which can result in involuntary dance-like movements, may not begin until more than 90 days after the onset of the initial streptococcal infection.
  
  
• Lumps under the skin (subcutaneous nodules).

Most signs and symptoms are temporary and will disappear without any lasting problems. However, the heart is vulnerable to permanent damage from rheumatic fever.