Rheumatic fever

Rheumatic fever is an inflammatory disease which may develop after a Group A streptococcal infection (such as strep throat or scarlet fever) and can involve the heart, joints, skin, and brain.

General information

Rheumatic fever is common worldwide and is responsible for many cases of damaged heart valves. In the Western countries, it became fairly rare since the 1950's, possibly due to higher hygienic standards. While it is far less common in the United States since the beginning of the 20th century, there have been a few outbreaks since the 1980s. Although the disease seldom occurs, it is serious and has a mortality of 2 - 5%.

Rheumatic fever primarily affects children between ages six and 15 and occurs approximately 20 days after strep throat or scarlet fever. In up to a third of cases, the underlying strep infection may not have caused any symptoms.

The rate of development of rheumatic fever in individuals with untreated strep infection is estimated to be 3 %. The rate of development is far lower in individuals who have received antibiotic treatment. Persons who have suffered a case of rheumatic fever have a tendency to develop flare-ups with repeated strep infections.

The recurrence of rheumatic fever is relatively common in the absence of maintenance of low dose antibiotics, especially during the first three to five years after the first episode of rheumatic fever. Heart complications may be long-term and severe, particularly if the heart valves are involved.

Diagnosis: Modified Jones Criteria

T. Duckett Jones, MD first published these criteria in 1944. They have been periodically revised by the American Heart Association in collaboration with other groups. Two major criteria, or one major and two minor criteria, when there is also evidence of a previous strep infection support the diagnosis of rheumatic fever. ^*^*

Major Criteria

Carditis: inflammation of the heart muscle which can manifest as congestive heart failure with shortness of breath, pericarditis with a rub, or a new heart murmur.
Migratory polyarthritis: a temporary migrating inflammation of the large joints, usually starting in the legs and migrating upwards.
Sydenham's chorea (St. Vitus' dance): a characteristic series of rapid movements without purpose of the face and arms. This can occur very late in the disease.
Erythema marginatum: a long lasting rash that begins on the trunk or arms as macules and spread outward to form a snakelike ring while clearing in the middle. This rash never starts on the face and is made worse with heat.
Subcutaneous nodules (a form of Aschoff bodies): painless, firm collections of collagen fibers on the back of the wrist, the outside elbow, and the front of the knees. These now occur infrequently.

Minor Criteria

Fever: temperature elevation
Arthralgia: Joint pain without swelling
Laboratory abnormalities: increased Erythrocyte sedimentation rate, increased C reactive protein, leukocytosis
Electrocardiogram abnormalities: a prolonged PR interval
Evidence of Group A Strep infection: positive culture for Group A Strep, elevated or rising Antistreptolysin O titre

Other Signs and Symptoms

Pathophysiology

Rheumatic fever is an autoimmune disease which occurs after an untreated Group A streptococcal infection, typically a throat infection. The antibodies formed against the bacteria attack parts of the body, typically the joints and the heart. This occurs because the streptococcal M antigen can stimulate B cells which are cross reactive with cardiac myosin.^*

Group A Streptococcus pyogenes has a cell wall that is composed of branched polymers which sometimes contain "M proteins" which are highly antigenic. The antibodies formed against these proteins sometimes cross-react with normal tissue causing damage. Depending on the site of damage, this can lead to the clinical symptoms described above. ^*

Treatment

The management of acute rheumatic fever is geared toward the reduction of inflammation with anti-inflammatory medications such as aspirin or corticosteroids. Individuals with positive cultures for strep throat should also be treated with antibiotics. Another important cornerstone in treating rheumatic fever includes the continuous use of low dose antibiotics (such as penicillin, sulfadiazine, or erythromycin) to prevent recurrence.

Infection

Patients with positive cultures for Streptococcus pyogenes should be treated with Penicillin as long as allergy is not present. This treatment will not alter the course of the acute disease.

Inflammation

Patients with significant symptoms may require corticosteroids. Salicylates are useful for pain.

Heart failure

Some patients develop significant carditis which manifests as congestive heart failure. This requires the usual treatment for heart failure: diuretics, digoxin, etcetera. Unlike normal heart failure, rheumatic heart failure responds well to corticosteroids.

Prevention

Prevention of recurrence is achieved by eradicating the acute infection and prophylaxis with antibiotics. The American Heart Association recommends prophylaxis continue at least 10 years.