Sexually transmitted infections (STIs)—also referred to as sexually transmitted diseases (STDs)—are those spread by sexual contact. They may also be spread from a pregnant woman to her fetus before or during delivery.

Exposure to an STI can occur anytime a person has sex or close contact that involves the genitals, the mouth, or the rectum with another person, but exposure is more likely if a person has many sex partners or does not use condoms. STIs can be prevented by not having sexual contact (abstinence).

STIs include:

• Chlamydia.
• Genital herpes.
• Genital warts or human papillomavirus (HPV). Certain types of HPV can cause cancer of the cervix in women.
• Gonorrhea.
• Hepatitis B.
• Syphilis.
• Trichomoniasis.
• Human immunodeficiency virus (HIV), which causes AIDS.
• Other infections that may be sexually transmitted, including hepatitis C, cytomegalovirus, scabies, and pubic lice.

Most STIs can be treated and cured, but some cannot. Some STIs, such as HIV and syphilis, can cause death.