Which of the following is a common sign of Lyme disease?

The presence of a bull's-eye rash, known as erythema migrans, is a hallmark sign of Lyme disease. This distinctive rash typically appears as a circular, red area surrounding a central clearing, resembling a target or bull's-eye. It usually develops within a few days to a month after a person is bitten by an infected tick, particularly the black-legged tick (Ixodes scapularis).

Recognition of this rash is crucial for early diagnosis and treatment of Lyme disease, as it can lead to more severe symptoms if left untreated. While other symptoms may accompany Lyme disease — such as fever, fatigue, and joint pain — the bull's-eye rash is particularly indicative of the disease's onset and serves as an important visual cue for diagnosis, distinguishing it from other illnesses.