Acute rheumatic fever is an illness caused by an autoimmune response to a bacterial infection with group A streptococcus, commonly called the strep bacteria. Infection with group A streptococcus can cause many illnesses, including sore throat (strep throat) and skin sores. In some cases, the immune system gets confused when reacting to the infection and the result is a generalised inflammatory illness that is called acute rheumatic fever (ARF).
ARF affects the heart, joints, brain and skin. The acute episode can last for several weeks with significant joint pain, fevers and other symptoms requiring hospitalisation. The symptoms of ARF typically leave no lasting damage to the brain, joints or skin. However, the damage to the heart valves may remain once the episode of ARF has resolved. This is known as rheumatic heart disease (RHD). Recurrent strep infections and episodes of ARF cause further damage to heart valves.