Rheumatic fever is common worldwide and is responsible for many cases of damaged heart valves. While it is far less common in the U.S. since the beginning of the 20th century, there have been a few outbreaks since the 1980s. Rheumatic fever primarily affects children between ages 6 and 15 and occurs approximately 20 days after strep throat or scarlet fever. In up to a third of cases, the underlying strep infection may not have caused any symptoms. The rate of development of rheumatic fever in individuals with untreated strep infection is estimated to be 3%. Persons who have suffered a case of rheumatic fever have a tendency to develop flare-ups with repeated strep infections.
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