Syphilis is a sexually transmitted infection caused by the bacterium Treponema pallidum subspecies pallidum. The signs and symptoms of syphilis vary depending in which of the four stages it presents (primary, secondary, latent, and tertiary). The primary stage classically presents with a single chancre (a firm, painless, non-itchy skin ulceration) but there may be multiple sores. In secondary syphilis a diffuse rash which frequently involves the palms of the hands and soles of the feet occurs. There may also be sores in the mouth or vagina. In latent syphilis there are little to no symptoms which can last for years. In tertiary syphilis there are gummas (soft non-cancerous growths), neurological, or heart symptoms. Syphilis has, however, been known as "the great imitator" as it may cause symptoms similar to many other diseases.