Herpes infections are very common. Fifty to 80 percent of American adults have oral herpes (HSV-1), which causes cold sores or fever blisters in or around the mouth. Genital herpes, caused by HSV-1 or HSV-2, affects one out of every six people in the U.S. age 14 to 49. Genital herpes infections can be asymptomatic, or can show up as outbreaks of blisters or sores.

These common viral conditions are transmitted through intimate person-to-person contact. In the case of HSV-1, kissing or oral sex can spread the infection to another person, while HSV-2 can be contracted through vaginal, anal or oral sex with someone who has the virus. A mother infected with a herpes virus can transmit the virus to her baby during birth if the virus is active at that time.

In rare cases, infection with HSV-1 or HSV-2 can lead to meningitis (inflammation of the covering of the brain and spinal cord) or encephalitis (inflammation of the brain).

Treatment for herpes infections can lessen the frequency or intensity of outbreaks.