What causes acute rheumatic fever (ARF)?

Updated: Dec 10, 2020
  • Author: Robert J Meador, Jr, MD; Chief Editor: Herbert S Diamond, MD  more...
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Although the mechanism by which streptococcal organisms cause disease is not entirely clear, overwhelming epidemiologic evidence suggests that ARF is caused by streptococcal infection, and recurrences can be prevented with prophylaxis.

Strains of group A streptococci that are heavily encapsulated and rich in M protein (signifying virulence in streptococcal strains) seem to be most likely to result in infection.

Group A Streptococcus (Streptococcus pyogenes) is thought to cause the myriad of clinical diseases in which the host's immunologic response to bacterial antigens cross-react with various target organs in the body, resulting in molecular mimicry. In fact, autoantibodies reactive against the heart have been found in patients with rheumatic carditis. The antibody can cross-react with brain and cardiac antigens, and immune complexes are present in the serum. The problem has been the uncertainty of whether these antibodies are the cause or result of myocardial tissue injury.

A study from New Zealand found a strong association between scabies infestation and ARF. Thornley et al documented that children who had been diagnosed with scabies were 23 times more likely to develop ARF or chronic rheumatic heart disease, compared with children who had no scabies diagnosis. Even after adjustment for confounders in a Cox model, the association remained strong, with an adjusted hazard ratio of 8.98 (95% confidence interval: 6.33-20.2). [10] Subsequently, Thornley et al reported that permethrin prescribing, as an indicator of scabies, is strongly associated with the incidence of ARF. [11]

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