Nearly seven in 10 people under age 50 – more than 3.7 billion teens and adults worldwide – are infected with herpes simplex virus type 1, a highly infectious and incurable disease, the World Health Organization announced Wednesday. More than 1 billion people are infected with HSV-1 in the Western Pacific region, while Southeast Asia has nearly 1 billion cases, according to WHO’s first global estimates, published Wednesday in an article in the journal PLOS ONE. More than 700 million people are infected in Africa, nearly 400 million in Europe and 320 million in North and South America.

Known as “oral herpes” and typically spread through kissing, oral sex and the use of shared objects like eating utensils, HSV-1 typically causes cold sores around the mouth. But it can also cause genital herpes, which leads to painful blisters and ulcers in the anal and genital areas. Although most cases of genital herpes are caused by herpes simplex virus type 2, which is transmitted almost entirely through sexual activity, “we know that increasingly HSV-1 is showing up in genital infections, and that’s sort of a trend that public health folks are watching,” said Fred Wyand, communications director at the American Sexual Health Association in Research Triangle Park, N.C. FULL REPORT