Overview of Sexually Transmitted Disease (STD)

A sexually transmitted disease (STD), also called sexually transmitted infection (STI) is a disease caused by a pathogen (e.g., virus, bacterium, parasite, fungus) that is spread from person to person primarily through sexual contact. STDs can be painful, irritating, debilitating, and life threatening. More than twenty sexually transmitted diseases have been identified.

Incidence and Prevalence of STDs

STDs occur most commonly in sexually active teenagers and young adults, especially those with multiple sex partners. An estimated 200 to 400 million people worldwide are infected—representing men and women of all economic classes.

According to the Centers for Disease Control and Prevention (CDC) in February 2013, about 20 million people are diagnosed with an STI each year in the United States, and there are about 110 million total STD cases. About half of these new infections occur in young people between the ages of 15 and 24. In 2011, the CDC reported about 1,412,000 new chlamydia infections and about 14,000 new cases of syphilis in the United States. Chlamydia is more common in people 15–24 years of age and syphilis is more common in men who have sex with men.

Generally, STD incidence has declined in the United States over the past 15 years, although rates among certain populations, including men who have sex with men, have increased. Improvements in STD screening and testing are believed to be responsible for the recent increase in reported STD infection.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 10 Jun 1998

Last Modified: 22 Apr 2013