Rheumatic fever is an inflammatory condition that develops when a strep throat infection triggers the immune system to attack the body’s own tissues, particularly the heart, joints, skin, and brain. It most commonly strikes children between the ages of 5 and 15, and globally it remains a serious problem: in 2021, rheumatic heart disease (its most dangerous long-term consequence) accounted for an estimated 3.85 million new cases and over 373,000 deaths worldwide, disproportionately affecting younger populations in low- and middle-income countries.
How Strep Throat Leads to Rheumatic Fever
Rheumatic fever doesn’t come from the strep bacteria directly damaging your organs. Instead, it’s an autoimmune reaction. After a throat infection with group A streptococcus, the immune system produces T cells designed to fight the bacteria. In some people, those T cells mistake the body’s own tissues for the invader and begin attacking them. This misdirected response is what causes the inflammation in the heart, joints, and nervous system.
Not everyone who gets strep throat develops rheumatic fever. It appears to require a combination of genetic susceptibility and infection with specific strains of streptococcus. Certain bacterial toxins called superantigens may play a key role by causing widespread, exaggerated activation of the immune system in susceptible individuals. Crowded environments like schools, daycare centers, military training facilities, homeless shelters, and correctional facilities increase the risk because they make strep infections spread more easily.
Recognizing the Symptoms
Rheumatic fever typically develops two to three weeks after a strep throat infection. Its symptoms can affect several parts of the body at once, and they vary widely in severity.
Joint Pain
Arthritis is usually the first symptom to appear, occurring in 60% to 80% of patients. The joints become red, swollen, and extremely tender, with the pain characteristically “migrating” from one joint to another. Large joints like the knees, ankles, and wrists are most commonly affected. The pain in one joint may ease just as another flares up.
Heart Inflammation
Carditis is the most serious manifestation, occurring in 50% to 80% of cases. It can involve all layers of the heart wall. The earliest signs are often a rapid heart rate or a new heart murmur detected by a doctor. In mild cases, a person may not notice any symptoms at all. In severe cases, it can cause chest pain, shortness of breath, and heart failure.
Involuntary Movements
Sydenham chorea is a neurological complication that shows up in 10% to 30% of cases, typically appearing one to eight months after the strep infection, much later than other symptoms. It causes involuntary, irregular jerking movements of the face, hands, or feet, often worse on one side of the body. These movements stop during sleep. Behavioral changes frequently accompany the physical symptoms: agitation, anxiety, emotional outbursts, inappropriate laughing or crying, and features resembling obsessive-compulsive disorder. Handwriting may deteriorate noticeably, and speech can become slurred.
Skin Signs
Erythema marginatum is a distinctive rash that occurs in fewer than 6% of patients. It appears as pale red or pink rings with raised edges and clear centers, found on the trunk and limbs but not the face. The rash is fleeting, fading from one area and reappearing in another. Small, firm, painless lumps called subcutaneous nodules can also form under the skin near joints, though both skin signs are uncommon.
How It’s Diagnosed
Doctors diagnose rheumatic fever using a standardized checklist known as the Jones Criteria, which sorts symptoms into “major” and “minor” categories. Major criteria include carditis, arthritis affecting multiple joints, chorea, erythema marginatum, and subcutaneous nodules. Minor criteria include fever (at or above 38.5°C), elevated markers of inflammation in blood tests, joint pain that doesn’t meet the threshold for full arthritis, and certain changes on an electrocardiogram.
For a first episode of rheumatic fever, a diagnosis requires evidence of a recent strep infection plus either two major criteria or one major and two minor criteria. In regions where rheumatic fever is more common, the diagnostic bar is slightly adjusted. For example, arthritis in a single joint counts as a major criterion in high-risk populations but not in low-risk ones. An echocardiogram can detect valve inflammation even before a murmur is audible, which counts as “subclinical carditis” and satisfies the carditis criterion.
Heart Valve Damage Over Time
The reason rheumatic fever gets so much attention is its potential to cause lasting heart damage. The mitral valve, which controls blood flow between the heart’s left chambers, is affected in nearly all cases of rheumatic heart disease. Early on, the valve may leak (regurgitation). Over years, repeated inflammation and scarring can stiffen and narrow it (stenosis). The aortic valve can also be involved, where calcium buildup and degeneration tend to develop over time.
During the initial episode, echocardiography may detect small nodules along the valve edges. These early lesions don’t usually destroy the valve or significantly impair its function. The real danger comes from long-term inflammation, especially after multiple episodes of rheumatic fever. Ongoing scarring disrupts the valve’s structure and flexibility, eventually preventing it from directing blood flow properly through the heart chambers. This can lead to heart failure, sometimes requiring valve surgery.
Treatment During an Episode
The first step is clearing any remaining strep infection with antibiotics. Beyond that, treatment focuses on controlling inflammation and managing specific symptoms.
For joint pain and swelling, anti-inflammatory medications like naproxen or ibuprofen are the recommended first-line treatment. Aspirin, once the go-to choice, is now used second line because of its less favorable safety profile. Initial high-dose therapy is typical, then tapered after one to two weeks. For severe heart inflammation, especially when heart failure is present, corticosteroids are recommended. If chorea doesn’t respond to initial medications, corticosteroids can be added to the treatment plan.
Preventing the First Episode
The most effective way to prevent rheumatic fever is to properly treat strep throat with antibiotics. Research from the American Heart Association shows that even when antibiotic treatment is started as late as nine days after strep symptoms begin, it effectively prevents a first attack of rheumatic fever. This is why getting a sore throat evaluated, especially in school-age children, matters so much. A simple course of antibiotics can stop the chain of events before the immune system mounts a damaging response.
Long-Term Prevention After a First Episode
Once someone has had rheumatic fever, they are at high risk of recurrence with future strep infections, and each recurrence increases the chance of permanent heart damage. Preventive (prophylactic) antibiotics are prescribed on an ongoing basis to stop new strep infections from taking hold. The duration depends on how severe the first episode was:
- Rheumatic fever without heart involvement: antibiotics for 5 years or until age 21, whichever is longer.
- Rheumatic fever with heart inflammation but no lasting valve damage: 10 years after the last episode, or until age 21, whichever is longer.
- Rheumatic fever with persistent valve disease: at least 10 years and until age 40, sometimes lifelong.
- Severe valve disease or after valve surgery: lifelong.
People whose daily lives bring them into regular contact with children or crowded settings, such as teachers and daycare workers, face higher ongoing exposure to strep and may need longer prophylaxis. Sticking with these regimens is one of the most important things a person can do to protect their heart from progressive damage.