Rheumatic fever | Description | Prevention | Causes and symptoms | Treatment

Rheumatic fever is a rare complication that occurs after an infection with Streptococcus pyogenes bacteria . The most common type of S. pyogenes infection is "strep throat," in which the tissues that line the pharynx become infected with the bacteria. Rheumatic fever does not occur if the initial strep infection is treated with antibiotics . Major symptoms of rheumatic fever include infection of the protective layers of the heart , arthritis (an inflammation of the joints), skin rashes, and chorea (a condition characterized by abrupt, purposeless movements of the face, hands, and feet). Rheumatic fever is treated with antibiotics, but recurrences are common. To prevent recurrences, preventive antibiotic therapy is administered for at least three years after an initial occurrence.

Rheumatic fever occurs most frequently among the poor in large cities, perhaps because this segment of the population does not have access to health care and is not treated promptly for strep infections. Rheumatic fever is also common in developing countries without access to antibiotics.

 Cause of rheumatic fever

Rheumatic fever occurs as a result of a primary infection with Streptococcus pyogenes. If the infection is not treated, the body's immune system starts to overreact to the presence of the bacteria in the body. Illnesses caused by such overreactions of the immune system are called hypersensitive reactions. Some of the symptoms of rheumatic fever, particularly the involvement of the heart, are thought to be caused by the hypersensitive reactions. Other symptoms may be caused by the release of toxins from the S. pyogenes bacteria that are spread to other parts of the body through the bloodstream.

Not all strains of S. pyogenes cause rheumatic fever; only certain strains of S. pyogenes, called the M strains, have been implicated in cases of rheumatic fever. In addition, not everyone infected with these strains of S. pyogenes will progress to rheumatic fever. Individuals with a specific type of antigen (an immune protein) on their immune cells, called the human leukocyte antigen (HLA), are predisposed to develop rheumatic fever following an untreated strep infection. The specific type of HLA antigen that predisposes a person to develop rheumatic fever is called the class II HLA. These individuals develop their susceptibility during early childhood. Children under two years of age rarely contract rheumatic fever; the incidence of the disease increases during childhood from ages five to 15 and then decreases again in early adulthood. Researchers are not sure about the exact mechanism that leads to susceptibility or the role that the class II antigen plays in susceptibility to rheumatic fever.

 Signs and symptoms of rheumatic fever

Rheumatic fever can be difficult to diagnose because the signs and symptoms are diverse. In order to simplify diagnosis , rheumatic fever is indicated if a person has two major manifestations of rheumatic fever, or one major manifestation and two minor manifestations. In both cases, evidence of strep infection is also necessary.

 

 Major signs of rheumatic fever

The most common sign of rheumatic fever is arthritis, or inflammation of the joints. Arthritis occurs in 75% of rheumatic fever patients. The arthritis is extremely painful and involves the larger joints of the body, such as the knee, elbow, wrist, and ankle. Symptoms include tenderness, warmth, severe pain , and redness. The inflammation resolves by itself in two to three weeks with no lasting effects.

Another common sign of rheumatic fever is carditis, or infection of the linings of the heart. Carditis occurs in 40-50% of patients. Often, the aortic (the valve that connects the left ventricle of the heart to the aorta) and mitral (the valve that connects the left atrium and left ventricle) valves become scarred, leading to a condition called stenosis. In stenosis, the delicate leaflets that make up the valve weld together. The valve is essentially "frozen" shut, obstructing the flow of blood through the heart. Carditis and stenosis cause few symptoms but are serious manifestations of rheumatic fever. If the carditis is severe, it may lead to heart failure. Congestive heart failure, in which the heart gradually loses its ability to pump blood, occurs in 5-10% of patients with rheumatic fever.

The third most common sign of rheumatic fever occurring in 15% of patients is chorea, in which the face, hands, and feet move in a rapid, non-purposeful way. Patients with chorea may also laugh or cry at unexpected moments. Chorea disappears within a few weeks or months, but is a particularly distressing sign of rheumatic fever.

The least common sign of rheumatic fever occurring in less than 10% of patients is the appearance of subcutaneous (under the skin) nodules. These nodules are painless and localize over the bones and joints. Nodules may last about a month before they disappear. A skin rash called erythema marginatum is also a sign of rheumatic fever. The rash is ring-shaped and painless, and may persist for hours or days and then recur.

 Minor signs of rheumatic fever

Typical minor signs of rheumatic fever include fever, joint pain, prior history of rheumatic fever, and laboratory evidence of a hypersensitive immune response to strep bacteria.

 Treatment and prevention

Rheumatic fever is treated primarily with antibiotics. In severe cases of carditis, corticosteroids may be used to reduce inflammation. Because rheumatic fever tends to recur, patients must continue antibiotic therapy in order to prevent subsequent strep infections. Typically, this preventive antibiotic therapy should last for three to five years after the initial infection. Some researchers recommend that preventive antibiotics be administered until early adulthood.

Aspirin is useful in treating arthritis caused by rheumatic fever. In fact, if arthritic symptoms respond particularly well to aspirin, the diagnosis of rheumatic fever is strengthened.

Rheumatic fever can be prevented entirely if strep infections are diagnosed correctly and antibiotic treatment is initiated within ten days of onset. A severe sore throat that is red and swollen, accompanied by fever and general fatigue, should be examined by a physician and tested for the presence of strep bacteria. Patients diagnosed with strep throat must be sure to take their full course of antibiotics, as incompletely healed infections may also lead to rheumatic fever.

 Resources

periodicals

Dinsmoor, Robert. "Watch your Strep." Current Health 2 20, no. 7 (March 1994): 14.

Fischetti, Vincent A. "Streptococcal M Protein." ScientificAmerican 244, no. 6 (June 1991): 58.

Guthrie, Robert. "Streptococcal Pharyngitis." American FamilyPhysician 42, no. 6 (December 1990): 1558.

Harrington, John T. "My Three Valves." New England Journal of Medicine 328, no. 18 (May 6, 1993): 1345.

other

"Guidelines for the Diagnosis of Rheumatic Fever: Jones Criteria." Journal of the American Medical Association 268, no. 15 (October 21, 1992): 2069.

 

Kathleen Scogna

KEY TERMS

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Antibiotic —A drug that targets and kills bacteria.

Antigen —A molecule, usually a protein, that the body identifies as foreign and toward which it directs an immune response.

Aortic stenosis —The welding of the leaflets of the valve that connects the left ventricle to the aorta.

Arthritis —Inflammation of the joints.

Carditis —Infection of the protective layers of the heart.

Chorea —Rapid, random movements of the face, hands, and feet.

Human leukocyte antigen (HLA) —A type of antigen present on white blood cells; divided into several distinct classes; each individual has one of these distinct classes present on their white blood cells.

Hypersensitive reaction —An immune reaction in which the body's immune system overreacts to the presence of antigens in the body; may lead to disease.

Mitral stenosis —The welding of the leaflets that make up the mitral valve of the heart.