Rheumatic fever is a delayed consequence of an untreated upper respiratory infection with group A streptococci (streptococcal pharyngitis or strep throat). Rheumatic fever can affect many parts of your body - heart, joints, nervous system and skin. Although rheumatic fever can occur at any age, it most frequently occurs in people between the ages of 6 and 15 years. The disease is twice as common in women as it is in men.

Symptoms of rheumatic fever generally appear within 5 weeks after an untreated streptococcal (strep) throat infection. Most cases of strep throat don't lead to rheumatic fever. In fact, even in untreated cases, only about 3 percent of people with strep throat develop rheumatic fever.

In more than half of all cases, rheumatic fever may affect the heart valves (rheumatic carditis) and interfere with normal blood flow through the heart. There's no cure for rheumatic fever. But it can be prevented by prompt and thorough treatment of a strep throat infection with antibiotics.

Signs and symptoms

Common signs and symptoms of a strep infection include:

• Sore throat
• Red and swollen tonsils
• Fever
• Headache
• Muscle aches

• Chest pain
• Fatigue
• Headache
• Sore throat

In as many as one-third of all cases, however, the initial strep infection may not cause any symptoms.

Signs and symptoms of rheumatic fever may include a combination of painful, swollen joints, chest pain, fatigue and shortness of breath. In diagnosing rheumatic fever, doctors generally look for either the presence of two of the following major criteria or the presence of one major plus two minor criteria. In all cases, evidence of a preceding strep throat infection is key to making a diagnosis of rheumatic fever.

Major criteria

• Inflammation of your heart, sometimes indicated by weakness and shortness of breath or chest pain. Your doctor might suspect heart inflammation as a result of a physical exam or from medical test results such as an electrocardiogram or a chest X-ray.
• Painful arthritis, most often affecting your ankles, wrists, knees and elbows, and migrating from joint to joint.
• Involuntary jerky movement of your limbs and face, or more subtle movement difficulties, such as marked deterioration in handwriting. This sign usually disappears over weeks to months.
• Broad, pink or faint-red, nonitching patches on your skin (uncommon).
• Lumps under the skin (uncommon).

Minor criteria

• Joint pain without inflammation
• Fever
• Previous rheumatic fever or evidence of rheumatic heart disease
• Abnormal heartbeat on an electrocardiogram
• Blood test indicating inflammation
• New heart murmurs

The exact cause of rheumatic fever isn't clear. Basically, in a few people, it seems that when the body fights a strep throat infection, other parts of the body also develop inflammation. For example, the heart valves aren't necessarily infected with the streptococcal bacteria, but they can be injured or inflamed as the body fights strep throat.