Which clinical feature is characteristic of cat scratch fever?

Painful regional lymphadenopathy is a hallmark feature of cat scratch fever, also known as Bartonella henselae infection. This condition typically arises after a scratch or bite from an infected cat and leads to the development of swollen, tender lymph nodes, particularly in the area closest to the injury. The lymphadenopathy usually occurs within one to two weeks after exposure and can persist for several weeks.

While fever and chills can occur in cat scratch fever, they are not as specific or characteristic as the painful swollen lymph nodes. A rash and conjunctivitis are more commonly associated with other infections or conditions and are not primary features of cat scratch fever. Similarly, cough and difficulty breathing would suggest respiratory issues unrelated to cat scratch fever, which primarily presents with localized lymphadenopathy and systemic symptoms like mild fever. Thus, the presence of painful regional lymphadenopathy strongly points to cat scratch fever as the correct diagnosis.