Which of the following symptoms is required to diagnose Kawasaki disease?

Kawasaki disease is a pediatric condition characterized by prolonged fever and a constellation of specific clinical features. To diagnose Kawasaki disease, a fever lasting more than five days is essential, along with at least four of the five defining symptoms: conjunctivitis, oral mucosal changes (such as cracked lips or strawberry tongue), cervical lymphadenopathy, rash, and changes in the extremities (such as swelling or desquamation).

In this case, "fever plus conjunctivitis" is a critical component of the diagnostic criteria. Conjunctivitis, specifically, refers to the bilateral nonpurulent conjunctival injection that is observed in many patients with Kawasaki disease. The presence of this symptom along with fever forms an important part of establishing the diagnosis, which helps differentiate it from other febrile illnesses.

Other symptoms like lip cracking or fissuring, rash, or cough do not encapsulate the diagnostic criteria as effectively as conjunctivitis. While those symptoms may present, they do not distinctly align with the diagnosis without the accompanying presence of fever for a sustained period. Conjunctivitis, therefore, stands out in this context as a required symptom, reinforcing the need for healthcare professionals to closely monitor and identify this symptom in patients presenting with prolonged fever for the potential diagnosis