Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs) and the older term venereal diseases, are infections that are spread by sexual activity, especially vaginal intercourse, anal sex, and oral sex. STIs often do not initially cause symptoms, which results in a risk of passing the infection on to others. Symptoms and signs of STIs may include vaginal discharge, penile discharge, ulcers on or around the genitals, and pelvic pain. Some STIs can cause infertility. Bacterial STIs include chlamydia, gonorrhea, and syphilis. Viral STIs include genital herpes, HIV/AIDS, and genital warts. Parasitic STIs include trichomoniasis. STI diagnostic tests are usually easily available in the developed world, but they are often unavailable in the developing world. Some vaccinations may also decrease the risk of certain infections including hepatitis B and some types of HPV. Safe sex practices, such as use of condoms, having a smaller number of sexual partners, and being in a relationship in which each person only has sex with the other also decreases the risk of STIs. Comprehensive sex education may also be useful. Most STIs are treatable and curable; of the most common infections, syphilis, gonorrhea, chlamydia, and trichomoniasis are curable, while HIV/AIDS and genital herpes are not curable. In 2015, about 1.1 billion people had STIs other than HIV/AIDS. About 500 million were infected with either syphilis, gonorrhea, chlamydia or trichomoniasis. At least an additional 530 million people have genital herpes, and 290 million women have human papillomavirus. STIs other than HIV resulted in 108,000 deaths in 2015. In the United States, there were 19 million new cases of STIs in 2010. Historical documentation of STIs in antiquity dates back to at least the Ebers Papyrus (c. 1550 BCE) and the Hebrew Bible/Old Testament (8th/7th centuries BCE). There is often shame and stigma associated with STIs. The term sexually transmitted infection is generally preferred over sexually transmitted disease or venereal disease, as it includes those who do not have symptomatic disease.
