Rheumatic fever is an inflammatory condition affecting the joints, heart, brain, and skin. It is not a direct infection, but an autoimmune reaction that occurs as a complication of a prior bacterial illness. In this condition, the body’s defense system mistakenly attacks its own tissues, causing widespread inflammation. The condition is not contagious itself, though the initial infection that precedes it can be spread from person to person.
The Bacterial Trigger
The development of rheumatic fever begins with an infection by Group A Streptococcus. This bacterium is responsible for common ailments like strep throat and scarlet fever, particularly in children aged 5 to 15. While millions of people contract strep infections, only a small fraction of them will go on to develop rheumatic fever.
The bacterium itself does not directly cause the joint pain or heart inflammation characteristic of rheumatic fever. The factor is an untreated or inadequately treated strep infection. If the bacteria are not fully eradicated from the body, it sets the stage for the immune system to initiate a secondary response. The onset of rheumatic fever symptoms occurs about one to five weeks after the initial strep infection has subsided.
Environmental and socioeconomic factors, such as overcrowded living conditions and limited access to healthcare, can increase the risk of widespread streptococcal infections. These conditions make it more likely for infections to go untreated, thereby raising the incidence of rheumatic fever. The bacteria can spread through respiratory droplets, and skin abrasions might also serve as an entry point.
The Autoimmune Malfunction
The core of rheumatic fever is a phenomenon known as molecular mimicry. This occurs when the immune system produces antibodies to combat Group A Streptococcus bacteria. These antibodies are designed to target molecules on the bacteria’s surface, but some of these molecules resemble proteins found in human tissues, particularly in the heart, joints, brain, and skin.
Because of this structural similarity, the antibodies cannot distinguish between the foreign invaders and the body’s own cells. Consequently, these antibodies, created to fight the infection, begin to bind to and attack healthy tissues. This misdirected assault triggers an inflammatory response in the affected organs, such as when antibodies attack the heart valves.
This process is why rheumatic fever is classified as an autoimmune disease; the body’s immune system is directly responsible for the tissue damage. The attack is not a sign of a persistent infection in the heart or joints, but a malfunction of the immune system’s recognition capabilities. The initial strep infection acts as the trigger, but the ensuing disease is driven by this internal attack.
Symptoms of the Autoimmune Attack
The autoimmune attack in rheumatic fever manifests as symptoms that correspond to the tissues being inflamed. One of the most common presentations is arthritis, affecting large joints like the knees, ankles, elbows, and wrists. This inflammation causes the joints to become painful, swollen, red, and warm, often migrating from one joint to another.
Inflammation of the heart, known as carditis, is the most serious manifestation and can lead to shortness of breath or chest pain. The autoimmune response can damage the heart’s valves, impairing their ability to function properly. In some cases, small, painless bumps may form under the skin over bony areas, and a distinctive, non-itchy rash may also appear.
A neurological symptom called Sydenham chorea can also occur. This condition results from inflammation in the part of the brain that controls movement and is characterized by jerky, uncoordinated, and involuntary movements, particularly of the face and hands. It can also cause emotional instability or changes in handwriting.
Diagnosis and Management of the Condition
Diagnosing rheumatic fever involves a clinical evaluation, as there is no single definitive test. Physicians rely on the Jones criteria, which categorize symptoms into major and minor manifestations. A diagnosis is confirmed when a patient exhibits a specific combination of these symptoms along with evidence of a preceding Group A Streptococcus infection.
Once diagnosed, the immediate goals of management are twofold. First, a course of antibiotics is prescribed to eliminate any lingering strep bacteria, removing the initial trigger for the autoimmune response. Second, anti-inflammatory medications are used to control the inflammation and alleviate symptoms. This helps to minimize damage to the body’s tissues, especially the heart.
For individuals who have had an episode of acute rheumatic fever, preventing a recurrence is a primary concern. Subsequent strep infections can re-trigger the autoimmune response, leading to cumulative damage, particularly to the heart valves, a condition known as rheumatic heart disease. To prevent this, long-term prophylactic antibiotics are often recommended to stop new strep infections from initiating another inflammatory cycle.