Rheumatic fever – Pathophysiology, Symptoms and Treatment

Definition

Rheumatic fever is a disease that can occur following an infection caused by the Group A streptococcus bacterium. If untreated, an infection such as ‘strep throat’ may lead to a delayed complication featuring widespread inflammation in other parts of the body, particularly the joints, heart, skin and brain.

Rheumatic fever is classed as an autoimmune disease because the inflammation is probably caused by the immune system’s reaction to the bacteria. While rheumatic fever can develop at any age, children between five and 14 years are at increased risk. Without treatment, the disease can lead to serious complications such as rheumatic heart disease.

Only a small percentage of people who have a streptococcal infection will develop rheumatic fever. The disease is rare in Australia except for remote parts of central and northern Australia where Aboriginal and Torres Strait Islander people, especially children, are at increased risk. About 250 to 350 Aboriginal and Torres Strait Islander children out of every 100,000 develop rheumatic fever. This rate is among the highest in the world.

Epidemiology

In developing countries, the magnitude of ARF is enormous. Recent estimates suggest that 33.4 million people worldwide have rheumatic heart disease and that 300,000-500,000 new cases of rheumatic fever (approximately 60% of whom will develop rheumatic heart disease) occur annually, with 230,000 deaths resulting from its complications. Almost this entire toll occurs in the developing world.

The incidence rate of rheumatic fever is as high as 50 cases per 100,000 children in many areas. Areas of hyperendemicity (eg, indigenous populations of Australia and New Zealand) see an incidence of 300-500 cases per 100,000 children, whereas the rates are approximately 50-fold lower in their nonindigenous compatriots. Rheumatic fever in the 21st century appears to be largely a disease of crowding and poverty. Even within developing countries with overall high rates of ARF, the segments of populations of poorer socioeconomic status and with higher rates of malnutrition suffer disproportionately.

Pathophysiology of rheumatic fever

Rheumatic fever can affect the heart, joints, central nervous system, and skin. Symptoms result from an abnormal immune response to the M proteins on the microorganisms that cross-react with normal body tissues. Antibodies react with streptococci bacterial wall antigen, laminin, cardiac myosin, and neuronal cells.

The antibodies’ reaction with laminin and cardiac myosin affects the endocardium, specifically the heart valves. The reaction that antibodies have with neuronal cells increases dopamine release causing chorea. The antibodies also affect the skin, muscles, and synovial joints. As a result of the antibodies reacting with these antigens, inflammation occurs in connective tissues including the joints, central nervous system, endocardium, and skin. This inflammation leads to damage to the tissues allowing for an increased risk of recurrence and further complications with the heart valves.

There is also a genetic component to the rheumatic fever that includes the HLA-DR 1 antigen and HLA-DR 6 antigen. These antigens contribute to a predetermined immune response that leads to severe, chronic rheumatic heart disease. While rheumatic heart disease affects all layers of the heart, the endocardium is the most susceptible, especially the heart valves. This can lead to bacterial growth, or vegetation, on the valves and chordae tendineae which impedes blood flow through the heart. This vegetation is comprised of fibrin deposits called Aschoff bodies

Risk factors

Factors that can increase the risk of rheumatic fever include:

Family history: Some people carry a gene or genes that might make them more likely to develop rheumatic fever.

Type of strep bacteria: Certain strains of strep bacteria are more likely to contribute to rheumatic fever than are other strains.

Environmental factors: A greater risk of rheumatic fever is associated with overcrowding, poor sanitation and other conditions that can easily result in the rapid transmission or multiple exposures to strep bacteria.

Causes of rheumatic fever

Rheumatic fever can occur after a throat infection from a bacteria called group A streptococcus. Group A streptococcus infections of the throat cause strep throat or, less commonly, scarlet fever.

Group A streptococcus infections of the skin or other parts of the body rarely trigger rheumatic fever. The link between strep infection and rheumatic fever isn’t clear, but it appears that the bacteria trick the immune system.

The strep bacteria contain a protein similar to one found in certain tissues of the body. The body’s immune system, which normally targets infection-causing bacteria, attacks its own tissue, particularly tissues of the heart, joints, skin and central nervous system. This immune system reaction results in swelling of the tissues (inflammation).

If your child receives prompt treatment with an antibiotic to eliminate strep bacteria and takes all medication as prescribed, there’s little chance of developing rheumatic fever.

If your child has one or more episodes of strep throat or scarlet fever that aren’t treated or aren’t treated completely, he or she might develop rheumatic fever.

Rheumatic fever symptoms

Rheumatic fever usually occurs about two to four weeks after a strep throat infection, and can be so mild you don’t even know you have it.

The symptoms vary and may include:

• Fever
• Painful and tender joints, most often the ankles, knees, elbows or wrists
• Pain that moves from joint to joint
• Red, hot or swollen joints
• Small, painless nodules under the skin
• Chest pain
• Heart murmur
• Fatigue
• Flat or slightly raised painless rash

It can also cause a temporary disorder of the nervous system. Symptoms include:

• Jerky, uncontrollable body movements in the hands, feet, and face
• Bursts of unusual behavior, such as crying or inappropriate laughing

Complications of rheumatic fever

Long-term heart problems can occur, such as:

• Damage to heart valves. This damage may cause leakage in the heart valve or narrowing that slows blood flow through the valve
• Damage to the heart muscle
• Heart failure
• Infection of the inner lining of your heart (endocarditis)
• Swelling of the membrane around the heart (pericarditis)
• Heart rhythm that is fast and unsteady
• Sydenham chorea

Diagnosis and test

The healthcare provider will ask about your child’s symptoms and health history, including having rheumatic fever or strep infections. They will give your child a physical exam. Your child may also have tests, such as:

Throat culture: This is a test to see if your child has strep throat or signs of a recent strep infection.

Echocardiography: This is an imaging test that uses sound waves (ultrasound) to make detailed pictures of the heart.

Electrocardiography: This is a test to measure the electrical activity of the heart.

Blood tests: For these, a small amount of blood is taken with a needle from a vein in an arm or hand.

Treatment and medications

Treatment of rheumatic fever focuses on not only controlling the inflammation but also on completely destroying the streptococcus bacteria to prevent reinfection in the future. Treatments include:

Antibiotics: Antibiotics like penicillin are administered first to treat the current disease. After the treatment for 5 to 10 years depending upon the condition, other antibiotics are given as preventive medicines to avoid reinfection in future.

Anti-inflammatory treatment: Pain relievers like aspirin or naproxen are given to reduce fever, pain, and inflammation.

Anticonvulsant medications: These are given to control the abnormal movements caused by Sydenham chorea.

Heart damage from rheumatic fever may not show up for many years. When your child grows up, he/she has to include the information in his/her medical history and get regular heart examinations.

Prevention

The most effective way to make sure your child doesn’t develop rheumatic fever is to start treating their strep throat infection within several days and to treat it thoroughly. This means ensuring your child completes all prescribed doses of medication.

Practicing proper hygiene methods can help prevent strep throat:

• Cover your mouth when coughing or sneezing
• Wash your hands
• Avoid contact with people who are sick
• Avoid sharing personal items with people who are sick