Rheumatic fever - Causes of rheumatic fever
NHS Choices Medical Reference
Most experts believe rheumatic fever is caused by the immune system malfunctioning.
Almost all cases develop after a throat infection with streptococcus bacteria.
During a throat infection, the lining of your throat becomes inflamed to prevent the infection from spreading. This is caused by your immune system responding to the infection.
In cases of rheumatic fever, it seems that the process of inflammation spreads throughout your body in an uncontrolled way. The inflammation can affect:
- the heart, which causes the symptoms of chest pain, fatigue and shortness of breath
- the joints, which causes the symptoms of arthritis
- the skin, which causes the symptoms of the skin rash and nodules
- the nervous system, which causes the symptoms of chorea (uncontrollable jerking) and the changes in personality associated with rheumatic fever
Exactly why the immune system suddenly stops working properly is unclear. One theory is that the streptococcal bacteria have a similar molecular structure to certain tissues in the body. So the immune system may begin by targeting the bacteria and then mistakenly go on to target tissues that share a similar molecular structure.
Another theory is that some people may be born with certain genetic factors that make their immune system more likely to malfunction after a throat infection.