Syphilis: Symptoms, Diagnosis, and 'Great Imitator' Characteristics

The STD caused by the bacterium Treponema pallidum is syphilis. It is often called the "great imitator" because many of its signs and symptoms are indistinguishable from those of other diseases. For example, the early stage of syphilis can cause sores that look like those of herpes simplex, and the later stages can cause rashes that resemble those of measles or lupus. This can make it difficult to diagnose syphilis, especially if a person does not have any other symptoms or if they have not been exposed to someone known to have the disease.