How common: Very. Twelve million people contract a sexually transmitted disease (STD) each year; forty million currently are infected.
Risk factors: Any sexual activity, including oral and digital sex, can put you at risk. Having multiple sex partners, having sex with an infected person and sharing hypodermic needles also increase your chance of contracting an STD.
Age group affected: STDs are most common in younger and middle-age people. Experts estimate that almost half the U.S. population will acquire an STD by age 35. Other statistics show that 86 percent of all STD...
