Most experts believe rheumatic fever is caused by the immune system overreacting to the presence of group A streptococcus bacteria.

Almost all cases develop a few weeks after a throat infection with group A streptococcus bacteria.

During this throat infection, the lining of the throat becomes inflamed as the immune system responds to the infection.

In rheumatic fever, the process of inflammation seems to spread through the body in an uncontrolled way. The inflammation can affect the:

  • heart, which causes the symptoms of chest painfatigue and shortness of breath
  • joints, which causes the symptoms of arthritis
  • skin, which causes the skin rash and nodules to develop 
  • nervous system, which causes the symptoms of chorea (uncontrollable jerking) and the changes in personality associated with rheumatic fever

It's not known why the immune system suddenly stops working properly. One theory is that the streptococcal bacteria have a similar molecular structure to certain tissues in the body. The immune system targets not only the bacteria, but also tissues that share a similar molecular structure.

Another theory is that some people may be born with certain genetic traits that make their immune system more likely to malfunction after a throat infection.

Page last reviewed: 29/10/2015
Next review due: 31/03/2018