Syphilis is a sexually transmitted disease (STD) caused by the bacterium Treponema pallidium. The infection is usually sexually transmitted, in which case it is called venereal syphilis.
The symptoms of syphilis are the same in men and women. They can be mild and difficult to recognise or distinguish from other STDs. Symptoms may take up to 3 months to appear after initial infection. Syphilis is a slowly progressing disease that has several stages. The primary and secondary stages of syphilis are very infectious.