22 Hard-To-Detect Illnesses, From The Commonplace To The Truly Bizarre

7. Chlamydia

Chlamydia is the most common STD in the United States, and yet most people afflicted with the disease have no idea they are carrying it. The disease usually doesn’t have symptoms, and can live in various parts of your body for decades. If left untreated in women, chlamydia can lead to severe pelvic pain or even infertility.