Introduction
Acute rheumatic fever is an inflammatory condition caused by streptococcal infection. It can cause damage to the heart vessels and the heart. It is an autoimmune condition where the immune system acts against the body’s tissues and joints, eventually leading to inflammation or swelling. It occurs in places where there is limited access to medical care. The body fights the healthy tissues. This destroys the tissues and organs instead of bacteria. In acute rheumatic fever, mortality can be prevented, but a quarter million people are dying because of this disease in poor and developing countries. With proper diagnosis and treatment, most deaths can be prevented. In developing nations, the ratio of disease occurrence is 100 to 200 per 100,000 people. The disease is due to overcrowding and poor medical care.
What Are the Causes of Acute Rheumatic Fever?
The condition is caused by streptococcal infection. Every streptococcus does not cause acute rheumatic fever. There is a particular type of streptococcus that can produce acute rheumatic fever. They can cause disease only if involved in specific areas of the body. For example, the streptococcus that consists of the throat only causes this fever. If it is present in other parts of the body, they do not cause the infection. The streptococcus present in the throat is followed by acute rheumatic fever. The streptococcal condition that causes sore throat, pharyngitis, and upper respiratory infections leads to acute rheumatic fever. Only 3 percent of the population develops this fever.
What Is Acute Rheumatic Fever?
Acute rheumatic fever generally does not affect children under five years and older than 15. It is very rare, but adults can also get rheumatic fever.
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Only beta-hemolytic streptococcus can cause acute rheumatic fever. Acute rheumatic fever is caused by beta-hemolytic streptococcus, a rheumatogenic strain of the Lancefield group.
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Streptococcal infections are common, but rheumatic infections are not common.
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Once the infection has started, it takes two to four weeks to develop into a full-fledged immune response.
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The fever is more common in children between 5 to 15 years of age. The immune response triggered by streptococcal infection will inappropriately cross-react with our tissues because some bacterial antigens are similar to human antigens.
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As a result, the immune system produces antibodies against the antigen. The immune system is supposed to attack bacterial antigens attack our tissues because the bacterial antigen structurally mimics our antigens. For example, the bacteria's cell wall containing the carbohydrate antigens is structurally very similar to heart valves.
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In post-streptococcal infection, multisystem immune-mediated non-suppurative inflammation, such as the cardiac tissues, skin, synovial joints, subcutaneous tissue, and the central nervous system, will occur.
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Since the rash is severe, lots of cytokines are produced. These cytokines go to the hypothalamus and precipitate fever. During rheumatic fever, multiple systems are inflamed.
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It produces symptoms such as sore throat, pharyngitis, or upper respiratory infection. Not all individuals are affected by the disease. Only 3 percent of the genetically vulnerable population is susceptible to the disease.
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The beta-hemolytic streptococcus produces a toxin called hemolysin that clears the surrounding red blood cells in blood agar.
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Hemolysin attacks the mucosa and causes inflammation of the pharynx. Macrophages will produce antibodies. The fever subsides after the initial immune response in the average population. Still, in genetically susceptible people (3 percent of the population), the fever does not subside, and the infection attacks other body parts.
What Are Subcutaneous Nodules in Acute Rheumatic Fever?
In this fever, the immune system cross-reacts with the body’s tissues of the subcutaneous area. There is a formation of non-tender, 1.5 to 1 cm, usually under the bony prominences on the external surface of the limbs and synovial sheets of tendons. The skin manifestations of acute rehabilitation. Subcutaneous nodules appear on the skin in response to the immune reactions of the body. The major criteria for diagnosis of acute rheumatic fever are polyarthritis, rheumatic chorea, carditis, erythema marginatum, and subcutaneous nodules. The minor criteria are arthralgia, fever, and C-reactive protein.
The subcutaneous nodules are small lumps under the skin in less than two percent of the patients. The painless nodules are found on the ankles, knees, elbows, and knuckles. The nodules formed are firm, mobile, and round. The size of the nodules ranges from 1 to 2 cm.
Subcutaneous nodules are one of the major criteria for acute rheumatic fever. The nodules are mobile, firm, and non-tender without induration or erythema. They are usually found around the elbow, over the scalp, and in the knee. They are freely mobile and painless. Palpation of the elbows and wrists exhibits subcutaneous bumps. They are invariably associated with severe carditis. They are self-resolvable and do not cause long-term complications.
What Are the Diagnostic Tests for Acute Rheumatic Fever?
Multiple tests are done for the diagnosis of the disease. Medical history, physical exams, and certain tests are made for examination. The tests include:
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Blood Tests - The results examine inflammation markers, such as C reactive protein and erythrocyte sedimentation rate. It detects the antibodies in the streptococcal bacteria in the blood.
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Echocardiogram - It shows the blood flow moving through the images of heart motion created by sound waves.
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Electrocardiogram (ECG or EKG) - The test records the heart's electrical activity. It detects heart enlargement and any abnormality in a heartbeat.
What Is the Treatment for Subcutaneous Nodules?
Antibiotics are prescribed to treat underlying bacterial infections. Penicillin or any other antibiotic is used to treat the streptococcus bacteria. After the first course, another course of antibiotics is prescribed to prevent the remission of the infection. People with heart inflammation might continue the antibiotic treatment for 5 to 10 years or longer. Anti-inflammatory drugs such as naproxen or aspirin reduce fever, pain, and inflammation. Corticosteroid is prescribed along with aspirin if the symptoms don't get better.
Conclusion
Acute rheumatic fever is a rare phenomenon. It develops only if the underlying streptococcal infection is not regressed or treated. Most of the time it occurs in genetically susceptible individuals. People require lifetime support who are affected by acute rheumatic fever.
