What is syphilis? What are common symptoms?

Syphilis is a sexually transmitted infection caused by a bacteria. The first sign of syphilis is a small, painless sore that may appear on the genitals, rectum, or inner mouth. Secondary symptoms include headaches, swollen lymph. nodes, fatigue, fever, weight loss, hair loss, and aching joints. If syphilis is left untreated for a long time, syphilis can cause serious damage to organs like the heart and brain. Syphilis is spread through direct contact with the syphilitic sores.