There is no scholarly evidence than Benjamin Franklin had syphilis, despite the widespread nature of the myth. Perhaps the story gained traction because Franklin was known as a womanizer even during his lifetime, although many of his affairs probably were not consummated.
Franklin is often said to have died of syphilis, but in fact he most likely died from pneumonia and a chest infection, called empyema. He was confined to his bed for a year before he died, but he did not exhibit symptoms of syphilis. He suffered from gout in the later part of his life and stayed at home because of that painful condition.