Although STDs are quite common, they are very difficult to track because many people infected with them experience no symptoms and go undiagnosed. What are STDs STDs are contagious venereal diseases that are passed from one person to another through sexual contact. Signs and Symptoms People infected with STDs often have symptoms but at times may have no symptoms at all which is the reason that using condoms and not engaging in high-risk behavior is so important. Gonorrhea Gonorrhea is an STD caused by the bacteria Neisseria gonorrhea. The bacteria can infect the cervix, urethra, throat, rectum, and eyes.
Women tend to have a lower incidence of symptoms than men do.
Syphilis Syphilis is an STD caused by the bacteria Treponema pallidum. Syphilis infection is divided into three stages, each with a different set of symptoms. Primary syphilis is the most contagious stage of the disease. There is usually one sore and it is painless. It can develop on the genitals, near the rectum, in the mouth or throat, or on the tongue or lips.