Sexually Transmitted Infections

The Facts

Sexually transmitted infections (STIs), or sexually transmitted diseases (STDs) as they used to be called, are a group of infections that can be acquired through sexual contact. You don't necessarily have to have sex to get STIs, but sexual activity is the most common way for them to be spread. The chances of getting a sexually transmitted infection are highest if you have unprotected sex, a condom tears during intercourse, your sexual partner has an STI, or your partner has sex with other people.

The infections are caused by different bacteria or viruses and have a wide variety of symptoms. The most common STIs include:

  • chlamydia (infection caused by the Chlamydia trachomatis bacteria)
  • genital herpes (viral infection usually caused by herpes simplex 1 or herpes simplex 2)
  • gonorrhea (infection caused by the Neisseria gonorrhoeae bacteria)
  • hepatitis B (inflammation of the liver caused by the hepatitis B virus)
  • HIV infection (infection caused by the human immunodeficiency virus)
  • HPV infection (infection caused by the human papillomavirus)
  • pubic lice (“crabs”; a parasitic infection)
  • syphilis (infection caused by the Treponema pallidum bacteria)


Read more about sexually transmitted infections and the different types of STIs by clicking the links below.