Sexually Transmitted Infections (STIs) and Related Conditions

What are STIs?

Sexually transmitted infections (STIs, also known as STDs) are passed from one person to another through intimate physical contact – such as heavy petting –  and from sexual activity including vaginal, oral, and anal sex. STIs are very common. In fact, CDC estimates 20 million new infections occur every year in the United States. STIs can mostly be prevented by not having sex. If you do have sex, you can lower your risk by using condoms and being in a sexual relationship with a partner who does not have an STI. STIs do not always cause symptoms, so it is possible to have an infection and not know it. That is why it is important to get tested if you are having sex. If you are diagnosed with an STI, know that all can be treated with medicine and some can be cured entirely.

There are dozens of STIs. Some STIs, such as syphilis, gonorrhea, and chlamydia, are spread mainly by sexual contact. Other diseases, including Zika and Ebola, can be spread sexually but are more often spread through ways other than sex.

The diseases, conditions, and infections below are listed in alphabetical order.

	Bacterial Vaginosis Any woman can get bacterial vaginosis. Having bacterial vaginosis can increase your chance of getting an STI.
	Chlamydia Chlamydia is a common sexually transmitted infection (STI) that can be easily cured. If left untreated, chlamydia can make it difficult for a woman to get pregnant.
	Gonorrhea Anyone who is sexually active can get gonorrhea. Gonorrhea can cause very serious complications when not treated, but can be cured with the right medication.
	Hepatitis Viral hepatitis is the leading cause of liver cancer and the most common reason for liver transplantation.
	Herpes Genital herpes is a common STI, and most people with genital herpes infection do not know they have it.
	HIV/AIDS HIV stands for human immunodeficiency virus. It weakens a person’s immune system by destroying important cells that fight disease and infection. No effective cure exists for HIV. But with proper medical care, HIV can be controlled. If left untreated, HIV can lead to acquired immunodeficiency syndrome (AIDS).
	Human Papillomavirus (HPV) Human papillomavirus (HPV) is the most common sexually transmitted infection in the United States. Some health effects caused by HPV can be prevented with vaccines.
	Pelvic Inflamatory Disease (PID) Pelvic Inflammatory Disease (PID) can lead to serious consequences including infertility.
	Syphilis Syphilis is a sexually transmitted infection (STI) that can have very serious complications when left untreated, but it is simple to cure with the right treatment.
	Congenital Syphilis (CS) is a disease that occurs when a mother with syphilis passes the infection on to her baby during pregnancy.
	Trichomoniasis Most people who have trichomoniasis do not have any symptoms.
	STIs and Infertility Chlamydia and gonorrhea are preventable causes of pelvic inflammatory disease (PID) and infertility.
	STIs During Pregnancy For a healthier baby, ask your doctor about STD testing.

Last Updated: March 2018
Content source: Centers for Disease Control and Prevention, Division of STD Prevention, National Center for HIV/AIDS, STD, and TB Prevention