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Acute rheumatic fever is an immune-mediated, multisystem inflammatory disease that occurs a few weeks after an untreated group A (-hemolytic) streptococcal (GAS) pharyngitis (sore throat) infection of the upper respiratory tract in children.
The major complication of this disease is cardiac involvement, which can eventually lead to severe heart valve damage. It is the commonest cause of heart disease in children. The initial attack of acute rheumatic fever occurs in most cases between the ages of 3 and 15 years.
The time frame for the development of symptoms relative to the sore throat and the presence of antibodies to the GAS organism strongly suggests an immunologic response. Antibodies directed against the M protein of certain strains of streptococci cross-react with glycoprotein antigens in the heart, joints, and other tissues to produce an autoimmune response through a phenomenon called molecular mimicry
Although only a small percentage of persons with untreated GAS pharyngitis develop RF, the incidence of recurrence with a subsequent untreated infection is substantially greater.
Rheumatic fever develops in children and adolescents following pharyngitis with group A beta-hemolytic Streptococcus (ie, Streptococcus pyogenes). The organisms attach to the epithelial cells of the upper respiratory tract and produce a battery of enzymes allowing them to damage and invade human tissues.
After an incubation period of 2-4 days, the invading organisms elicit an acute inflammatory response with 3-5 days of sore throat, fever, malaise, headache, and an elevated leukocyte count.
Group A streptococci elaborate the cytolysis toxins streptolysins S and O. Of these, streptolysin O induces persistently high antibody titers that provide a useful marker of group A streptococcal infection and its non-suppurative complications.
A diagnosis of rheumatic heart fever is made after confirming antecedent rheumatic fever using the modified Jones criteria.
The Jones criteria require the presence of 2 major and one minor or 1 major and 2 minor criteria for the diagnosis of rheumatic fever.
It entails migrating polyarthritis, carditis (signs of cardiac failure, persistent tachycardia, pericardial rub, or heart murmurs), Sydenham’s chorea, erythema marginatum, and subcutaneous nodules.
Entails: Past history of rheumatic fever, raised Erythrocyte sedimentation rate, fever, arthralgia, prolonged PR interval on the electrocardiogram, elevated acute phase reactants (increased erythrocyte sedimentation rate, presence of C-reactive protein, and leukocytosis.
Anti-streptolysin-0-titre (ASOT) – titer of 1:300
Throat swab for B-haemolytic Streptococci group A for C&S
Erythrocyte sedimentation rate
A chest x-ray will demonstrate features of cardiomegaly
Management to eradicate the streptococcal infection from the throat:
• Amoxicillin 250–500mg (children 25–50mg/kg in divided doses) TDS for 10 days
• If allergic to penicillin or amoxicillin, erythromycin 12.5mg/kg QDS for 10 days
Control fever and inflammation: Aspirin: 75–100mg/kg/day in 4–6 divided doses. Treatment continued until fever and joint inflammation are controlled and then gradually reduced over a 2-week period.
Treat failure if present.
Treat chorea if present with haloperidol 25mcg/kg (0.025mg/kg) TDS.
Admit for strict bed rest until symptoms resolve.
Early treatment of streptococcal sore throat with benzathine penicillin 1.2 mega units STAT dose OR Phenoxymethyl penicillin 125–250mg TDS for 10 days.
If there has been previous acute rheumatic fever without carditis, give benzathine penicillin 1.2 mega units monthly for 5 years or up to the age of 18 years, whichever is longer. OR Erythromycin 125–250mg BD for 5 years for those sensitive to penicillin.
If there has been previous acute rheumatic fever with carditis give benzathine penicillin 1.2 mega units OR Erythromycin 125–250mg BD for those sensitive to penicillin for life.
Emphasize the need for follow up for prophylaxis.
Advise that rheumatic heart disease is a known complication