Depends on Staging. When left untreated, syphilis progresses through three distinct stages that include the original genital sore, a rash that covers the body, and neurosyphilis. Between these stages, the infection becomes dormant and the patient is asymptomatic. This is one of the many reasons you should always use protection during intercourse. Your partner may not even be aware of his or her infection.
Yes. Eventually everyone who has been infected with syphilis has symptoms.