What is a Sexually Transmitted Infection?

Sexually transmitted infections (STIs) are also known as a sexually transmitted diseases (STDs). Transmission can occur through vaginal or anal sex, but some STIs can also be transmitted through other types of sexual activity such as kissing, oral/genital sex, or sexual activity that involves non-penetrating, external genital contact. STIs may be present without symptoms.

STIs can happen to anyone, regardless of sexual orientation, race, age, or gender. It's not who you are, it's the behaviors that you engage in that put you at risk for an STI.

What are the most common STIs?

STIs can be caused by viruses, bacteria, or parasitic organisms. Those caused by viruses include:

Some of the STIs caused by bacteria include:

Why talk about Sexually Transmitted Infections(STIs)?

Many people DON'T KNOW they are infected because most STIs do not cause any symptoms at first. If untreated, STIs can cause long-term health problems. According to The American Social Health Association (ASHA), 1 in 2 sexually active persons will contract an STI by age 25. Each year, one in four teens contracts an STI. By age 20, 86% of men and 77% of women have had sexual intercourse (Youth Risk Behavior Surveillance and Kaiser Family Foundation). 15% of all high school students have had four or more sexual partners (Youth Risk Behavior Surveillance and Kaiser Family Foundation). The median age of reported sexual intercourse is 16.1 years for females and 16.9 years for males (Youth Risk Behavior Surveillance and Kaiser Family Foundation). Slightly more than half of American teenagers age 15-19 have engaged in oral sex (National Center for Health Statistics).