Final answer:
The most common problem in rheumatic fever is carditis, an autoimmune response to Streptococcus pyogenes infection that causes damage to heart valves, leading to rheumatic heart disease.
Step-by-step explanation:
Common Problem in Rheumatic Fever
The most common problem in rheumatic fever is damage to the heart valves, known as carditis. This condition arises following an infection with Streptococcus pyogenes which causes strep throat. The body generates antibodies to fight the infection, but due to molecular mimicry, these antibodies can also target and damage heart tissue. This autoimmune response can lead to scarring and stiffness of the valve leaflets, creating a significant health issue known as rheumatic heart disease. In patients with a history of rheumatic fever, subsequent infections can exacerbate heart valve damage, particularly within the first 3-5 years after the initial attack.