Sexually transmitted diseases (STDs)—also referred to as sexually transmitted infections (STIs)—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 STD 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. STDs can be prevented by not having sexual contact (abstinence).

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