(CNN) -- As much as 16 percent of the U.S. population between the ages of 14 and 49 has genital herpes, according to a government study released Tuesday.

And sexually transmitted diseases of all varieties infect 19 million more Americans every year -- a rate that costs the health care system some $16 billion annually, the National Health and Nutrition Examination Survey (NHANES) found. The study was released by the Centers for Disease Control and Prevention as part of the the National STD Prevention Conference in Atlanta, Georgia.

The herpes simplex 2 virus -- one of the most common sexually transmitted diseases in the United States -- causes painful, recurring genital sores.