It's curable, the first sign of syphilis is a small sore and it appears after the infection. Symptoms appear in about 3 weeks. In it's second stage, rashes on other parts of the body begin to appear. The third stage can last up to multiple years. It can, in fact, be treated in this stage but it is much, much smarter to treat it in the first two stages.
A person with a speech-related disorder can know what to say, they just have trouble saying it. It has nothing to do with their knowledge, so they wouldn't be less intelligent just because of their disorder.
