Rheumatic Fever (RF) is a complication of Strep Throat. The bacteria Group A Beta-Hemolytic Streptococcus (GABHS; S. pyogenes), commonly called “Strep,” triggers a poorly-understood auto-immune reaction, which can affect the joints, skin, brain, and most seriously, the heart valves. It used to be common, and still is in poor areas of the world, but not so in developed countries (although local outbreaks still occur occasionally). It mostly affects children 5-15, is very rare over 30. Treating Strep Throat within 9 days will prevent RF.
When RF damages heart valves, some children have acute heart failure with significant shortness of breath. It occurs around 3 weeks after Strep throat (which may have been very mild, or even without symptoms). Though most patients recover from acute RF, many go on to have chronic disease of the heart valves, often eventually requiring surgery for valve replacement. These patients need monthly injections of penicillin for 5-10 years after their first episode, to prevent future Strep infections that can worsen the damage.
Arthritis from RF moves from joint to joint, is treatable with aspirin or NSAIDs (ibuprofen, etc.), and does not cause permanent joint destruction. Brain disease from RF, called Sydenham’s Chorea (or “St. Vitus Dance”), consists of involuntary jerky movements, muscle weakness, & frequent mood changes. It begins 8 months after Strep Throat, so tests for Strep are usually negative. Treatment is penicillin as for heart disease; most patients recover within a few months to 2 years.
Don’t confuse Rheumatic Fever with “Scarlet Fever.” The latter is nothing more than Strep Throat with a rough red rash that feels a little like sandpaper when rubbed. It used to be from a dangerous strain of Strep, but now is no different from Strep Throat without a rash. Rheumatic Fever, on the other hand, also caused by Strep, is a lot different.