If left untreated, syphilis can move to the secondary stage. This stage of syphilis can develop 17 days to 6 1/2 months after infection and symptoms can last from 2 to 6 weeks.
Symptoms in this stage include a rough, reddish-brown rash or spots on the palms of hands, soles of feet, or rashes on other parts of the body, including the neck, head and torso. Other symptoms could include headache, fever, and generally not feeling well.
The symptoms will go away on their own, but the disease will still be present if untreated. It will then enter into a latent stage, which has no signs or symptoms.
The latent stage begins when the primary and secondary stage symptoms are gone and the infection has been left untreated. During this stage, which can last for as long as 20 years, there are no symptoms, but syphilis is still there.