What causes the herpes simplex virus?
Characterized by blister-like lesions that occur over an eight- to 10-day period most often around the lips, oral mucosa, or tongue, the virus is highly contagious and can spread easily by direct skin-to-skin contact. The two most common forms of the virus are herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). HSV-1 is most often associated with infections of the oral cavity, with 90 percent of the US population exposed to this virus. HSV-2 is most often associated with genital herpes infections, with 25 percent of the US population ages 25 to 45 exposed to this virus. However, research suggests that both types of HSV can infect both the mouth and the genitals.
