Yikes—more than 3.7 billion people under the age of 50 are infected with HSV-1, according to the World Health Organization's first global estimates
"Almost everyone has herpes" is a phrase you've probably heard once or twice. But how true is that really? We finally have some hard numbers on those unsightly cold sores: More than 3.7 billion people under the age of 50— that's 67 percent of the world's population—are infected with herpes simplex virus type 1 (HSV-1), according to the World Health Organization's (WHO) first global estimates, published this week in the journal PLOS ONE.
Quick high school health class refresh: The herpes virus is categorized into two types, herpes simplex virus type 1 (HSV-1) and herpes simplex virus type 2 (HSV-2). Both types are highly infectious and incurable, but HSV-1 is primarily transmitted by oral-oral contact and in most cases causes "orolabial herpes"—AKA cold sores—around the mouth. The majority of HSV-1 infections occur during childhood and are never cleared. (Here's how to tell: Is That a Herpes Cold Sore—or Just a Zit?)
On the other hand, HSV-2 is almost entirely sexually transmitted through skin-to-skin contact and causes genital herpes. However, as the report notes, HSV-1 does have the potential to be transmitted through oral sex and can also cause genital infections. In fact, in developed countries (like the U.S., Western Europe, Australia, and New Zealand), genital herpes due to HSV-1 has increased particularly among young people, in part due to a rise in the frequency of oral sex, the WHO explains. (Here's How to Talk to Your Partner About Your STI Status—without making it a huge deal.)
Also of note: Women are more likely to acquire genital herpes than men (whether it's caused by HSV-1 or HSV-2), the WHO says. Not to mention, "women have more painful outbreaks than men do," says H. Hunter Handsfield, M.D., a professor emeritus at the University of Washington Center for AIDS and STD. (Find out more on that and other Dangerous Sleeper STDs.)
Although the prevalence of HSV-1 varies widely by region (its highest in Africa, South-East Asia and Western Pacific), the overall message of the report is simple: The global burden of HSV-1 infection is huge. The WHO hopes "these estimates will be used to develop appropriate prevention messages, manage and counsel patients with symptomatic genital herpes, develop improved treatment regimens and diagnostic tests, and ultimately, develop HSV vaccines."