Rheumatic fever (RF) is a fairly rare inflammatory condition in developed countries that can develop as a complication of untreated strep throat caused by group A streptococcal infections.

It primarily affects children between the ages of 5 and 15, but it can also occur in adults.

Symptoms of RF may include fever, joint pain and swelling, chest pain, fatigue, and skin rashes.

It can lead to inflammation in various parts of the body, such as the joints, skin, brain, and in 50% to 80% of people, in the heart. Heart inflammation is called carditis.

If left untreated, rheumatic fever can cause long-term damage to the heart valves, leading to rheumatic heart disease.

Learn how rheumatic fever causes carditis, as well as its symptoms and how it’s treated.

RF can cause carditis due to an autoimmune response triggered by certain strains of group A streptococcal bacteria.

If you have a streptococcal infection, your body’s immune system produces antibodies to fight the bacteria. In some cases, it’s possible for these antibodies to mistakenly target proteins in the heart — as well as other tissues — leading to inflammation.

In the case of carditis, the antibodies target the heart tissues, particularly the heart valves. This inflammatory response can result in swelling, scarring, and dysfunction of the heart valves, leading to a serious condition called rheumatic heart disease.

Medical researchers don’t fully understand the exact mechanism by which the immune response causes carditis in people with RF, but it’s believed to involve molecular mimicry, where the proteins on the streptococcal bacteria resemble proteins in the heart, leading to the immune system attacking both the bacteria and the heart tissues.

Carditis can present with several symptoms in people with RF. These may include:

  • chest pain or discomfort that can range from mild to severe
  • irregular or fast heartbeat
  • difficulty breathing or shortness of breath
  • fatigue or general weakness, even with minimal activity
  • fever
  • fluid build-up in the legs or abdomen due to heart dysfunction

Additionally, a medical professional may be able to detect atypical heart sounds, known as murmurs, during a physical examination.

RF treatment usually involves taking antibiotics to eliminate the streptococcal bacteria that causes the condition.

Treating the inflammation that it causes, including in the heart, often includes taking anti-inflammatory drugs.

Additional treatment targets the other symptoms of RF.

In severe cases, people with RF may require ongoing monitoring and treatment to prevent complications and protect heart health.

Carditis, or swelling of the heart tissue, is a common serious complication of RF.

If you experience symptoms of strep throat, you should see a medical professional to treat this condition and prevent it to progressing to RF. Symptoms of strep throat include:

  • sore throat
  • swollen or tender lymph nodes, which are bean-shaped structures just under the jawline
  • fever
  • difficulty swallowing
  • headache
  • fatigue
  • nausea or vomiting
  • body aches
  • skin rash

Also, see a medical professional soon if you experience additional symptoms of RF, such as:

  • joint pain and swelling
  • chest pain or discomfort
  • involuntary jerky movements, muscle weakness, known as chorea
  • pea-sized lumps under the skin