Acute rheumatic fever is a serious inflammatory condition that can develop when a strep throat infection goes untreated. Although it has become less common in Canada thanks to widespread antibiotic use, it remains a significant health concern that can cause lasting damage to the heart, joints, nervous system, and skin. Understanding the warning signs early is essential for preventing long-term complications.
What Causes Acute Rheumatic Fever and Who Is at Risk?
Rheumatic heart disease is one of the most serious consequences of this condition, making early diagnosis and treatment critical. The illness most commonly affects children and young adults between the ages of 5 and 25, and even milder cases can lead to permanent cardiac damage over time. This guide explains how Canadians can recognise the symptoms, understand the causes, and access appropriate care.
How Is Acute Rheumatic Fever Diagnosed? Treatment and Prevention When to See a Doctor Frequently Asked Questions About Acute Rheumatic Fever
What Is Acute Rheumatic Fever?
Major Symptoms of Acute Rheumatic Fever (Jones Criteria)
Symptom Description Severity Frequency in Cases
Carditis (Heart Inflammation) Inflammation of the heart layers, potentially causing murmurs, chest pain, and shortness of breath; may lead to permanent valve damage Severe — can cause long-term complications 40–60% of cases
Migratory Polyarthritis Painful, swollen joints that move from one joint to another, most commonly affecting knees, ankles, elbows, and wrists Moderate to Severe — highly painful but resolves without permanent damage 75% of cases
Sydenham’s Chorea Involuntary, rapid movements of the face, hands, and feet caused by inflammation of the central nervous system Moderate — distressing but typically self-limiting 10–30% of cases
Erythema Marginatum A distinctive pink, ring-shaped skin rash with clear centres that spreads outward, primarily appearing on the trunk and limbs Mild — not painful or itchy, but diagnostically significant Less than 10% of cases
Subcutaneous Nodules Small, firm, painless lumps under the skin located over bony prominences such as the elbows, knees, and spine Mild — rare but associated with severe carditis Less than 5% of cases
Acute rheumatic fever develops after an infection caused by Group A streptococcal bacteria — the same bacteria responsible for strep throat. The body’s immune system, while fighting the infection, mistakenly attacks its own tissues. This causes inflammation in the heart, joints, nervous system, and skin.
However, not everyone who gets strep throat develops acute rheumatic fever. Studies suggest that only about 3.5% of people with untreated streptococcal throat infections go on to develop the condition. It is most common in children and young adults between the ages of 5 and 25.
Thanks to modern antibiotic treatment, severe cases are now rare in Canada. Even so, milder forms of the disease can still lead to serious heart complications over time. For more background, visit Health Canada’s official health information portal.
What Causes Acute Rheumatic Fever?
The direct cause of acute rheumatic fever is a throat infection caused by Group A beta-haemolytic streptococcus bacteria. This is the same organism behind common strep throat and scarlet fever. The inflammation begins roughly one to five weeks after the initial throat infection.
The immune system produces antibodies to fight the strep bacteria. Unfortunately, those antibodies can also attack the body’s own tissues, particularly in the heart and joints. This process is known as an autoimmune reaction.
In addition, certain environmental and genetic factors may make some individuals more likely to develop acute rheumatic fever than others. Crowded living conditions and limited access to healthcare can also increase risk, particularly in remote or underserved communities across Canada.
Recognising the Symptoms of Acute Rheumatic Fever
The symptoms of acute rheumatic fever can vary widely from person to person. Some people experience only mild joint pain, while others develop significant heart problems. Knowing the warning signs early can make a real difference in outcomes.
Joint Symptoms
Joint inflammation, called arthritis, is one of the most common signs of acute rheumatic fever. It typically appears one to five weeks after a strep throat infection. The joints become swollen, warm, red, and very painful — even without being touched.
The arthritis tends to move from one large joint to another. It most often affects the knees, wrists, ankles, and elbows. The hips and shoulders are affected less often. Each time a new joint is involved, the person may develop a fever again.
Importantly, joint symptoms usually resolve on their own within a few days and do not cause permanent joint damage. However, the heart involvement can be a much more serious concern.
Heart Symptoms (Rheumatic Carditis)
Heart inflammation, known as carditis, is the most serious complication of acute rheumatic fever. It can affect all three layers of the heart — the inner lining (endocardium), the muscle (myocardium), and the outer sac (pericardium). When all three are affected together, this is called rheumatic pancarditis.
Myocarditis, or inflammation of the heart muscle, is common but often has no symptoms. Some people notice a rapid or irregular heartbeat that seems out of proportion to their fever. A doctor may detect an abnormal heart sound or murmur during an examination.
Endocarditis causes scarring and thickening of the heart valves over time. The mitral and aortic valves are most commonly affected. This can lead to valve narrowing (stenosis) or leakage (insufficiency), which may require medical management years later. Learn more about how rheumatic fever affects the heart at Mayo Clinic.
Pericarditis, or inflammation of the outer sac around the heart, can cause chest pain and muffled heart sounds. It is often mild and resolves without lasting damage.
Sydenham’s Chorea
Sydenham’s chorea is a neurological complication of acute rheumatic fever. It involves sudden, uncontrolled, jerky movements of the body. These movements are irregular and unpredictable, and they cannot be controlled by the person experiencing them.
This condition appears gradually, often weeks or even months after the initial strep infection. Children may become unusually restless or emotional. They may have trouble writing, speaking clearly, or holding objects. Uncontrolled facial grimacing is also common.
The movements worsen with physical activity and fatigue. Doctors will also notice reduced muscle tone during a physical exam. In most cases, Sydenham’s chorea eventually resolves on its own, but it can last for several months.
Skin Symptoms
Two skin-related signs can appear with acute rheumatic fever, though both are relatively uncommon. The first is a rash called erythema marginatum — a pink, ring-shaped rash with a pale centre. It appears mainly on the trunk and upper arms and tends to come and go quickly.
The second sign is the presence of small, firm, painless lumps under the skin, called subcutaneous nodules. These can be felt over bony areas such as the elbows and knees. Both of these skin findings are most often seen in people who also have heart involvement.
How Is Acute Rheumatic Fever Diagnosed?
Doctors use a set of established diagnostic criteria to identify acute rheumatic fever. These criteria include major and minor categories, along with evidence of a recent streptococcal infection.
Major criteria include:
Carditis (heart inflammation)
Arthritis (joint inflammation)
Sydenham’s chorea (uncontrolled movements)
Erythema marginatum (ring-shaped skin rash)
Subcutaneous nodules (firm lumps under the skin)
Minor criteria include:
Fever
Joint pain without visible inflammation
Elevated inflammatory markers in blood tests (such as ESR or CRP)
Specific changes seen on an electrocardiogram (ECG)
A previous episode of acute rheumatic fever
A diagnosis is confirmed when a person meets two major criteria, or one major and two minor criteria, along with proof of a recent strep infection. A throat swab or blood test for streptococcal antibodies helps confirm this. Furthermore, an echocardiogram (heart ultrasound) and ECG are used to assess any heart involvement.
Treatment and Prevention
Treatment for acute rheumatic fever focuses on three goals: eliminating the strep infection, reducing inflammation, and protecting the heart from further damage.
Doctors typically prescribe penicillin or amoxicillin to clear the streptococcal infection. Anti-inflammatory medications such as aspirin or corticosteroids are used to reduce joint pain and fever. In more severe cases with heart involvement, corticosteroids may be preferred.
Preventing repeat episodes is critical. Each recurrence of acute rheumatic fever increases the risk of permanent heart damage. As a result, long-term antibiotic prophylaxis (preventive antibiotics) is often recommended — sometimes for many years. Your family doctor or a specialist will determine the appropriate duration based on the degree of heart involvement.
Therefore, treating strep throat promptly with antibiotics remains the single most effective way to prevent acute rheumatic fever from occurring in the first place. If your child complains of a sore throat with fever, it is worth getting tested. The World Health Organization’s fact sheet on rheumatic heart disease also outlines the global importance of strep prevention.
When to See a Doctor
You should speak with your family doctor or visit a walk-in clinic if your child develops a sore throat with fever that does not improve within a couple of days. Early testing and treatment for strep throat can prevent acute rheumatic fever from developing.
Seek medical attention right away if you or your child shows signs of joint swelling, chest pain, an irregular heartbeat, or uncontrolled body movements after a recent throat illness. These symptoms need prompt evaluation — do not wait to see if they go away on their own.
In Canada, your provincial health plan covers visits to your family doctor and walk-in clinics. If you do not have a family doctor, a walk-in clinic can assess your symptoms, arrange a throat swab, and refer you to a specialist if needed. Always consult a healthcare professional for any diagnosis or treatment decisions — the information in this article is for general educational purposes only.
Frequently Asked Questions About Acute Rheumatic Fever
What is the difference between strep throat and acute rheumatic fever?
Strep throat is a bacterial throat infection caused by Group A streptococcus. Acute rheumatic fever is a complication that can develop if strep throat is left untreated or undertreated. Not everyone with strep throat gets rheumatic fever, but treating strep early with antibiotics greatly reduces the risk.
Can acute rheumatic fever cause permanent heart damage?
Yes, acute rheumatic fever can cause lasting damage to the heart valves, a condition known as rheumatic heart disease. The mitral and aortic valves are most commonly affected. Repeated episodes of rheumatic fever increase the risk of serious valve damage over time.
Who is most at risk for acute rheumatic fever?
Acute rheumatic fever most commonly affects children and teenagers between the ages of 5 and 25. It is rare before age 3 and less common after age 25. Children in crowded living conditions or with limited access to healthcare may face a higher risk.
How is acute rheumatic fever treated in Canada?
Treatment typically involves antibiotics to clear the strep infection, anti-inflammatory medications to ease joint pain and fever, and long-term preventive antibiotics to avoid recurrence. Your family doctor or a specialist will create a treatment plan based on the severity of your symptoms and whether your heart is affected.
Is acute rheumatic fever contagious?
Acute rheumatic fever itself is not contagious. However, the strep throat infection that triggers it can spread from person to person through respiratory droplets. Treating strep throat promptly and practising good hand hygiene helps prevent the spread of the bacteria.
Can adults get acute rheumatic fever?
According to Mayo Clinic’s overview of rheumatic fever, this information is supported by current medical research.
For more information, read our guide on reactive arthritis, another condition triggered by infection.
Acute rheumatic fever is most common in children and young adults, but it can occur in adults who have had strep throat. Recurrences tend to decrease with age. If you are an adult with a history of rheumatic fever, discuss long-term monitoring with your family doctor.
Key Takeaways
Acute rheumatic fever is triggered by untreated Group A strep throat infections.
It can cause inflammation in the heart, joints, skin, and nervous system.
Heart valve damage is the most serious long-term complication.
Doctors use established criteria — including major and minor signs — to make a diagnosis.
Treatment includes antibiotics, anti-inflammatory medication, and preventive long-term antibiotics.
Treating strep throat early is the best way to prevent acute rheumatic fever.
If you or your child has symptoms, visit your family doctor or a walk-in clinic promptly.
Always speak with a healthcare professional for advice tailored to your specific situation.
Frequently Asked Questions
What is acute rheumatic fever?
Acute rheumatic fever is an inflammatory disease that can develop after an untreated or inadequately treated Group A streptococcal throat infection (strep throat). It primarily affects children aged 5–15 and can cause serious damage to the heart, joints, nervous system, and skin if not promptly diagnosed and treated.
What are the symptoms of acute rheumatic fever?
Common symptoms include painful, swollen joints (especially knees and ankles), fever, chest pain, shortness of breath, a distinctive skin rash called erythema marginatum, small painless nodules under the skin, and involuntary jerky movements known as Sydenham’s chorea. Symptoms typically appear 2–4 weeks after a strep throat infection.
How is acute rheumatic fever treated in Canada?
Treatment includes antibiotics (usually penicillin) to eliminate remaining streptococcal bacteria, anti-inflammatory medications like aspirin or naproxen to reduce joint pain and fever, and corticosteroids for severe heart inflammation. Long-term preventive antibiotics are often prescribed to prevent recurrence and protect against rheumatic heart disease.
Can acute rheumatic fever be prevented?
Yes. The most effective prevention is promptly treating strep throat with a full course of antibiotics prescribed by a doctor. Completing the entire antibiotic course is essential, even if symptoms improve early. People who have already had rheumatic fever may require long-term preventive (prophylactic) antibiotics to prevent recurrent episodes.
When should you see a doctor for acute rheumatic fever symptoms?
See a doctor immediately if your child develops joint pain, fever, chest pain, or unusual movements following a recent sore throat or strep throat diagnosis. Early medical attention is critical — untreated acute rheumatic fever can lead to permanent heart valve damage, a serious condition called rheumatic heart disease.