In a significant shift, the federal government is now calling abstinence and monogamy “the most reliable way” to avoid sexually transmitted diseases, a $16 billion annual problem that hits as many as 10 million teens a year.

In a very long rewrite of the “Sexually Transmitted Diseases Treatment Guidelines, 2010,” the Centers for Disease Control and Prevention dropped the old language that monogamy and abstinence were just “a reliable way” to avoid STDs.