Pathogenesis

There are two theories concerning the pathogenesis of rheumatic fever (RF):

Cross-reactive antibodies:

• clear association with previous streptococcal infection
• anti-viral titres are often elevated - antistreptolysin O antibodies
• streptococci are not directly involved as lesions are sterile
• the more serious the streptococcal infection, the more likely is the development of RF, on average 3% of all streptococcal pharyngitides will cause RF
• all recurrences of RF are preceded by strep infection
• recurrence rate range from 5-50%
• the development of RF depends on the virulence of the organism and also on the immune response genes of the host
• putative cross-reactive bacterial antigens include hyaluronic acid and M proteins

Autoimmunity:

• streptococcal infection stimulates the production of antibodies which react with the heart but not with the streptococci
• autoantibodies are present in Aschoff bodies