Rheumatic Fever Health Article

Definition

Rheumatic fever (RF) is an illness that occurs as a complication of untreated or inadequately treated strep throat infection. Rheumatic fever causes inflammation of tissues and organs and can result in serious damage to the heart valves, joints, central nervous system and skin.

Rheumatic fever is rare in the United States, though there were outbreaks in both New York City and in Utah in the 1990s. The disease is more prevalent in the developing world, where rheumatic fever is the leading cause of heart disease. In some countries, as many as one to two percent of children are afflicted with the disease.

Description

Though the exact cause of rheumatic fever is unknown, the disease usually follows the contraction of a throat infection caused by a member of the Group A streptococcus (strep) bacteria (called strep throat). The streptococcus A bacteria has also been linked to many serious diseases, including "flesh-eating" disease and toxic shock syndrome. About 9,700 cases of invasive diseases linked to strep A were reported in the United States in 1997. Rheumatic fever may occur in people of any age, but is most common in children between the ages of five and 15. Poverty, overcrowded living conditions, and inadequate access to medical care increase the likelihood of contracting the disease.

The initial strep throat is easily treated with a 10-day course of antibiotics taken orally. However, when a throat infection occurs without symptoms, or when a patient neglects to take the prescribed medication for the full 10-day course of treatment, there is up to an estimated 3% chance that he or she will develop rheumatic fever. Other types of strep infections (such as of the skin) do not put the patient at risk for RF.

Causes & symptoms

Two different theories exist as to how a bacterial throat infection can result in rheumatic fever. One theory, less supported by research evidence, suggests that the bacteria produce some kind of poisonous chemical (toxin). This toxin is sent into circulation throughout the bloodstream, thus affecting other systems of the body. Research more strongly supports the theory that the disease is caused by an interaction between antibodies produced to fight the group A streptococcus bacteria and the heart tissue. The body produces immune cells (antibodies), that are specifically designed to recognize and destroy invading agents. The antibodies are able to recognize the bacteria because the bacteria contain special markers called antigens on their surface. Due to a resemblance between Group A streptococcus bacteria's antigens and antigens present on the body's own cells, the antibodies mistakenly attack the body itself, specifically heart muscle.

In 2002, a report announced that scientists had mapped the genome (genetic material) of an A streptococcus bacterium responsible for acute rheumatic fever. The discovery will help researchers map the factors in the strain of bacterium that help it overcome the body's defenses.

It is interesting to note that members of certain families seem to have a greater tendency to develop rheumatic fever than do others. This could be related to the above theory, in that these families may have cell antigens that more closely resemble streptococcal antigens than do members of other families.

Symptoms of rheumatic fever usually begin one to six weeks after a sore throat. Symptoms may include fatigue and fever, stomach pain, and vomiting. In about 75% of all cases of RF one of the first symptoms is arthritis. The joints (especially those of the ankles, knees, elbows, and wrists) become red, hot, swollen, shiny, and extremely painful. Unlike many other forms of arthritis, symptoms may not occur symmetrically (affecting a particular joint on both the right and left sides, simultaneously). Rather, pain may move from joint to joint. The arthritis of RF rarely strikes the fingers, toes, or spine. The joints become so tender that even the touch of bed sheets or clothing is terribly painful.

A peculiar type of involuntary movement, coupled with emotional instability, occurs in about 10% of all RF patients (the figure used to be about 50%). The patient begins experiencing a change in coordination, often first noted by changes in handwriting. The arms or legs may flail or jerk uncontrollably. The patient seems to develop a low threshold for anger and sadness. This feature of RF is called Sydenham's chorea or St. Vitus' dance.

A number of skin changes are common in rheumatic fever patients. A rash called erythema marginatum develops (especially in those patients who will develop heart problems from their illness), which takes the form of pink splotches that may eventually spread into each other. The rash does not itch. Bumps the size of peas or larger may occur under the skin. These are called subcutaneous nodules; they are hard to the touch, but not painful. These nodules most commonly occur over the knee and elbow joint, as well as over the spine.

The most serious result of RF is called pancarditis (pan means total; carditis refers to inflammation of the heart). Pancarditis is an inflammation that affects all aspects of the heart, including the lining of the heart (endocardium), the sac containing the heart (pericardium), and the heart muscle itself (myocardium). Heart damage caused by RF has the most serious long-term effects. The valves within the heart (structures that allow the blood to flow only in the correct direction, and only at the correct time in the heart's pumping cycle) are frequently damaged, which may result in blood leaking back in the wrong direction, or being unable to pass a stiff, poorly moving valve. Damage to a valve can result in the heart having to work very hard in order to circulate the blood. The heart may not be able to "work around" the damaged valve, which may result in a consistently inadequate amount of blood entering the circulation. About 40-80% of all RF patients develop a form of carditis. Heart damage, however, may not be apparent until months or years after a bout with rheumatic fever. The effect of the disease on the heart also depends on the avoidance of recurrences. The severity of heart damage is often related to the number of attacks of RF a patient experiences.