Understanding Rheumatic Fever

Medically Reviewed by Poonam Sachdev on February 08, 2024
6 min read

Rheumatic fever is a serious illness that can be life-threatening if left untreated. It happens when strep throat, caused by a bacteria called group A streptococcus, isn't treated properly. Symptoms usually start a few weeks after having strep throat and can include fever, muscle aches, swollen and painful joints, and sometimes a red rash. Sometimes, though, the infection may have been too mild for you to spot.

The joints that are most commonly affected are the knees, ankles, elbows, and wrists. The pain can move from one joint to another. But the greatest danger from the disease is the damage it can do to the heart. More than half of the time, it damages the heart valves, making the heart work harder to pump blood. Over time, this damage can lead to a serious condition called rheumatic heart disease, which can eventually cause heart failure.

Rheumatic fever can also cause a temporary nervous system disorder called Sydenham's chorea, previously known as St. Vitus' dance. This disorder causes rapid, jerky movements of the body, usually on one side. It can make it hard to focus or write for people with mild cases, while more severe cases can cause uncontrollable twitching in the arms, legs, or face, along with muscle weakness and emotional outbursts.

Thanks to antibiotics, rheumatic fever is now rare in developed countries. However, there has been a recent increase in cases in the U.S., especially among children in poor urban areas. The illness tends to happen more often in cool, damp weather during winter and early spring and is most common in the northern states of the U.S.

Scarlet fever vs. rheumatic fever

Scarlet fever is a highly contagious and typically mild bacterial disease that causes fever, sore throat, and a rash. The illness is connected to rheumatic fever in a couple of ways. Both stem from the group A streptococcus bacteria. One cause of rheumatic fever is untreated scarlet fever. While you can spread scarlet fever, rheumatic fever is not contagious.

Rheumatic fever happens when your body reacts to certain group A streptococcus bacteria. Instead of just fighting off the bacteria, your body's antibodies mistakenly attack your own tissues. This starts with the joints and can then affect the heart and nearby tissues. A very small number of people who have strep throat, less than 0.3%, end up getting rheumatic fever. Experts believe there are other factors involved too, like having a weak immune system. You can also get rheumatic fever if you don't treat a scarlet fever infection.

How often does strep throat cause rheumatic fever?

About 0.3%-3% of people with a strep throat infection develop rheumatic fever, even without treatment.

Is rheumatic fever contagious?

No. Since it's an immune response and not an infection, you can't catch this illness from another person. But if you have the group A strep or scarlet fever infection, you can pass it on to others.

  • Swollen, tender, red, and extremely painful joints -- especially the knees, ankles, elbows, or wrists
  • Fever
  • A red, raised, lattice-like rash, usually on the chest, back, and abdomen
  • Nodules, or small bumps, over the swollen joints
  • Chest pain, fast heartbeat, or shortness of breath (caused by heart involvement)
  • Jerky movements of arms, legs, or facial muscles that you can't control (called chorea)

These symptoms can show up 1-5 weeks after a strep throat or scarlet fever infection where these infections were not treated properly. But sometimes, people with rheumatic fever do not recall having a sore throat.

Monitor a sore throat

Pay attention to sore throats, especially in children. If your child has a severe sore throat without other cold symptoms, accompanied by a fever higher than 100.4 F, or a milder sore throat that continues for more than 2 or 3 days, see a doctor. It may be strep throat, which should be treated with antibiotics.

Call your doctor about rheumatic fever if you have:

  • Symptoms of rheumatic fever, especially a recent sore throat.
  • A sore throat without other cold symptoms, plus a fever higher than 101 F and swollen glands in your neck.
  • Sudden and unexplained joint pain after recovering from strep throat.

Rheumatic fever can affect anyone who's had strep throat, scarlet fever, or impetigo. But some people are more likely to get the illness, including: 

  • Kids aged 5-15 years
  • People in large groups such as schools, day-care centers, and military training facilities
  • People who've had rheumatic fever in the past and get strep throat, scarlet fever, or impetigo again

To figure out if you have the streptococcus bacteria, your doctor will do a throat culture. This uncomfortable but safe procedure involves swabbing a sample of throat mucus. Your doctor will send it to the lab for analysis, which usually takes 24 hours. Some doctors use a rapid strep test that can give results in about 5 minutes, but it isn't as accurate as the culture.

Your doctor will also give you a complete exam, which includes listening to your heart for any signs of trouble, such as a heart "murmur" (indicating potential valve issues). They will also look for other telltale symptoms, such as arthritis in more than one joint and small nodules that often appear on the joints, especially the elbows.

Other tests to diagnose rheumatic fever include:

  • A blood test that checks for antibodies related to a recent group A strep infection
  • Electrocardiogram or EKG to find out how well your heart is working
  • Echocardiography or echo, which shows your heart muscle in action

Your doctor will prescribe standard treatments that can lower your chances of heart disease and other health issues related to rheumatic fever. You'll probably use these treatments for a long time. Alternative therapies can also help by working alongside regular treatments to ease symptoms and help stop the illness from coming back.

You'll need plenty of rest, and your doctor may have you take penicillin or other antibiotics to kill the bacteria that caused the fever. To stop it from coming back, you may need to take antibiotics for a long time. And, if you have a fever, swelling, arthritic joint pain, or other symptoms, your doctor can prescribe aspirin or other medicines that ease swelling, such as ibuprofen or naproxen . They may also give you corticosteroids. If you have rheumatic heart disease, you'll need to take antibiotics at certain times, like before getting dental work or surgery, to stop your heart valve from swelling up again. In severe cases, surgery can fix the damage to your heart valves and stop heart failure from happening.



Weeks or even months after having rheumatic fever, you may still have joint and tissue swelling. This swelling could cause long-term health problems in some people. Another health issue, rheumatic heart disease, usually crops up years after your original illness, but heart valve damage can happen even when you still have symptoms.

Other types of heart damage from rheumatic fever include:

  • Valve stenosis, or a narrowing of the heart valve, which limits blood flow through the valve
  • Valve regurgitation, which is when blood flows backward across a heart valve due to an improperly closing valve flap
  • Heart muscle damage caused by swelling from rheumatic fever, which affects how well your heart pumps
  • Irregular heartbeat, known as atrial fibrillation (AFib), which is caused by damage to the heart valves and other parts of your heart

Rheumatic fever is a rare but serious bacterial illness that can result from untreated strep throat or scarlet fever. You'll usually get symptoms 2-4 weeks after a strep infection. Though rare in developed countries, the illness has resurfaced in the U.S. Other health problems from the disease, such as heart damage, can show up years after you were first sick. Treatments include antibiotics and medicine to lower swelling, while people with severe cases may need surgery to repair heart damage.