Rheumatic fever is an inflammatory disease that is caused by a bacteria named Streptococcus pyogenes. This organism is responsible for a number of infections in our body.
- Pharyngitis (strep throat)
- Skin infections like impetigo (superficial skin), erysipelas and cellulitis (deep layers of skin)
- Necrotizing fasciitis (life-threatening infection of fascia requiring urgent surgery)
- Scarlet fever
- Toxic shock syndrome
- Post infection syndromes: Glomerulonephritis and rheumatic fever following throat and skin infections.
Rheumatic fever is thought to be caused by antibody cross reactivity.
What is antibody cross reactivity?
When a person is infected with a bacteria, there is development of antibody against it which usually tries to kill and destroy the pathogen. In cross reactivity issues, the antibody destroys the pathogen as well as the normal tissues of the body resulting in damage of different organs. In rheumatic fever the antibody produced against Streptococcus pyogenes destroys heart valve, heart muscles, skin, brain and different joints.
Rheumatic fever usually develops two to three weeks following a sore throat. Acute rheumatic fever is usually a disease of children between the ages of five and 15
How to diagnose rheumatic fever?
According to revised Jones criteria, the diagnosis of rheumatic fever can be made when two of the major criteria, or one major criterion plus two minor criteria, are present along with evidence of streptococcal infection: elevated or rising antistreptolysin O titre or DNAase, positive throat culture etc.
The major criteria includes:
Carditis: Myocarditis, pericarditis or pancarditis
The minor criteria are:
Fever (100.8 - 102 F)
Raised ESR or CRP
ECG showing features of heart block
Fig: Conducting system of heart
If a patient has chorea or carditis we should not wait for major or minor criteria. Chorea or carditis by itself indicates rheumatic fever.
What is chronic rheumatic heart disease?
Chronic rheumatic heart disease (RHD) results from repeated inflammation with fibrinous repair of heart valves. The most important changes of the valve include leaflet thickening, commissural fusion, and shortening and thickening of the tendinous cords. As a result, valve stenosis or regurgitation ensue. About half of the patients with acute rheumatic fever develop valve disease in the long run. It can damage any valve but most frequently affected valves are mitral and aortic valves. However, symptoms associated with the inflammation may not be seen until 20-40 years later. Fortunately, this infection was much more common before the introduction of antibiotics to treat it in the 1950s.
How to treat acute rheumatic fever?
Anti inflammatory medications like aspirin or corticosteroids are used initially. If throat swab shows growth of the organism then antibiotic like penicillin is used. If the patient is allergic to penicillin, erythromycin is an alternative antibiotic. In some cases, using aspirin in children may result in the development of Reyes's syndrome. We should stop aspirin when we suspect it and use other NSAIDs like ibuprofen and short course steroids.
If one attack of rheumatic fever has already occurred, we should administer monthly injections of long acting penicillin (or oral antibiotics) for a period of five years. If there is evidence of carditis, the length of therapy may be up to 40 years.