Which of the following is a major manifestation in the modified Jones' criteria for acute rheumatic fever?

The major manifestations in the modified Jones criteria for acute rheumatic fever are comprised of specific clinical features that reflect the effects of rheumatic fever following a streptococcal infection. Among these, carditis and arthritis are recognized as significant manifestations.

Carditis refers to the inflammation of the heart, which can involve the pericardium, myocardium, and endocardium, potentially leading to severe complications such as valvular disease. Arthritis typically presents as a migratory polyarthritis, commonly affecting the large joints, such as the knees, ankles, elbows, and wrists. This combination highlights the systemic inflammation associated with rheumatic fever.

While options like arthritis and fever, or carditis and prolonged PR interval encompass components related to rheumatic fever, they do not represent the same level of critical manifestation as carditis and arthritis, which are definitive major criteria used to establish the diagnosis. Moreover, erythema marginatum and elevated ESR, although important, align more closely with minor criteria.

In summary, the pairing of carditis and arthritis stands out as a core aspect of the modified Jones criteria, effectively capturing the clinical severity and implications of acute rheumatic fever.