Pelvic inflammatory disease itself is not necessarily contagious, but many of the bacteria that cause it are contagious. PID develops when bacteria move from the vagina into the upper reproductive organs. These bacteria may be spread through sexual contact - PID is commonly caused by the bacteria responsible for gonorrhea and chlamydia. In some cases, though, the infection may be caused by bacteria that are normally found in the vagina. These bacteria aren't contagious. In general, reduce your risk of getting an STD that can lead to PID by using a condom and limiting your number of sex partners.