Sexually Transmitted Infections

What is a sexually transmitted infection (STI)?

It is an infection passed from person to person through intimate sexual contact. STIs are also called sexually transmitted diseases, or STDs.

How many people have STIs and who is infected?

In the United States about 19 million new infections are thought to occur each year. These infections affect men and women of all backgrounds and economic levels. But almost half of new infections are among young people ages 15 to 24. Women are also severely affected by STIs. They have more frequent and more serious health problems from STIs than men. African-American women have especially high rates of infection.

How do you get an STI?

You can get an STI by having intimate sexual contact with someone who already has the infection. You can't tell if a person is infected because many STIs have no symptoms. But STIs can still be passed from person to person even if there are no symptoms. STIs are spread during vaginal, anal, or oral sex or during genital touching. So it's possible to get some STIs without having intercourse. Not all STIs are spread the same way.

Can STIs cause health problems?

Yes. Each STI causes different health problems. But overall, untreated STIs can cause cancer, pelvic inflammatory disease, infertility, pregnancy problems, widespread infection to other parts of the body, organ damage, and even death.

Having an STI also can put you at greater risk of getting HIV. For one, not stopping risky sexual behavior can lead to infection with other STIs, including HIV. Also, infection with some STIs makes it easier for you to get HIV if you are exposed.

What are the symptoms of STIs?

Many STIs have only mild or no symptoms at all. When symptoms do develop, they often are mistaken for something else, such as urinary tract infection or yeast infection. This is why screening for STIs is so important. The STIs listed here are among the most common or harmful to women.