Final answer:
Rheumatic fever is often a sequela of untreated or inadequately treated strep throat caused by S. pyogenes, leading to an autoimmune response that can result in carditis and potential damage to heart valves.
Step-by-step explanation:
Rheumatic fever can occur following an episode of untreated or inadequately treated pharyngitis (strep throat) caused by Streptococcus pyogenes. This condition is a nonsuppurative sequela that typically presents in children a few weeks after the initial throat infection. It involves an immune-mediated response that can lead to serious complications such as rheumatic heart disease, especially when it involves inflammatory damage to heart valves, known as carditis.
Acute rheumatic fever is associated with an autoimmune reaction where antibodies produced against the S. pyogenes bacterium cross-react with the body's own tissue, leading to carditis and potential valve damage. Proper diagnosis and treatment of the initial S. pyogenes infection are crucial in preventing this potentially life-threatening sequelae.