Rheumatic Fever

Rheumatic fever is common worldwide and is responsible for many cases of damaged heart valves. . 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. 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
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 abnormalitie: 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 associated signs and symptoms are epistaxis and abdominal pain.

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.