A new study released in the World Health Organization's PLOS One journal shows that two-thirds of people -- or 3.7 billion -- under age 50 are infected with the herpes simplex virus type 1 (HSV-1).
In the Americas, around 39 percent of women and 49 percent of men are infected, while in the Eastern Mediterranean, 75 percent of both men and women are infected. In Africa, that number rises to 87 percent.
HSV-1 most commonly causes skin lesions, or cold sores, around the mouth but research shows that it may increasingly cause genital herpes as well. Rarely, HSV-1 can cause infections that lead to blindness or encephalitis.
While there are medications to suppress the virus or prevent outbreaks, there is currently no cure or vaccine for HSV-1. The WHO has urged increased global monitoring of the virus.