Yes you’re right @ElleBelle syphilis has been with us a long time. Thankfully today we have penicillin which is an effective cure. Syphilis today manifests itself differently from early times when people could become quite disfigured by the infection. These days syphilis is mostly diagnosed by a blood test and many people don’t have symptoms that are easily recognisable. Have a look here for more about syphilis.
@Lube_Man we actually diagnose syphilis in five stages: Primary, Secondary, Early Latent, Late Latent & Tertiary. The different stages have to do with the kind of symptoms present, the infectiousness (whether you can pass it on to someone), and how long a person has had the infection. The staging will also determine how long antibiotics are needed.
You may be interested to know that Syphilis is only contagious in the first two years (primary & secondary stages) and tertiary syphilis is now very rare!