Syphilis is a bacterial STD that can cause sores, rash, and organ damage if not treated. Learn about the causes, stages, diagnosis, and complications of syphilis and how to prevent it. Syphilis is a bacterial STI transmitted by skin-to-skin contact during sex. It causes chancre sores or rashes on the penis, vagina, anus, and mouth. Syphilis is a sexually transmitted infection caused by a type of bacteria. We explain the symptoms, complications, and more. Syphilis develops in stages. The symptoms vary with each stage. But the stages may overlap. And the symptoms don't always happen in the same order. You may be infected with syphilis bacteria without noticing any symptoms for years. Primary syphilis The first symptom of syphilis is a small sore called a chancre (SHANG-kur). The sore is often painless. It appears at the spot where the bacteria entered your body. Most people with syphilis develop only one chancre. Some people get more than one ...
