Which disease is characterized by a "bull's-eye" rash?

The disease characterized by a "bull's-eye" rash is Lyme disease. This distinctive rash, known as erythema migrans, typically appears as a circular, red lesion with a central clearing, resembling a target or bull's-eye. It often develops after a person is bitten by a tick infected with the bacterium Borrelia burgdorferi, which is the cause of Lyme disease.

The bull's-eye rash is significant because it is one of the early signs of Lyme disease and can occur within a few days to several weeks after exposure. Recognizing this rash is crucial for early diagnosis and treatment, which can prevent more severe symptoms and complications associated with the disease.

In contrast, Rocky Mountain spotted fever is associated with a different type of rash, often involving small, red spots that eventually may lead to petechiae. Syphilis may present with a rash, but it does not typically have the characteristic bull's-eye appearance; instead, it is often generalized and may be accompanied by other systemic symptoms. Chickenpox has a well-known vesicular rash, but it is not connected to the bull's-eye pattern associated with Lyme disease.