Some people with syphilis don't have any signs of infection. In other people, the signs may be very mild. They might not even know they have it. But even if the signs of infection go away on their own, the germs are still alive. They can cause serious health problems many years later.
Blood tests can find out for sure.
Sometimes other tests can show how far the syphilis has spread. For example, your doctor may want to look at your spinal fluid. This is a way to see if the syphilis germs have spread to your nervous system. Syphilis is almost always passed through sex. It also can be passed from an infected mother to her baby during pregnancy.