Worldwide, more than 3.7 billion people aged younger than 50 years — or 67% of the population — are infected with herpes simplex virus type 1 (HSV-1), according to the World Health Organization's (WHO) first global estimates of HSV-1 infection.
HSV-1 and HSV-2 are both highly infectious and incurable. HSV-1 is primarily transmitted by oral–oral contact and in most cases causes cold sores around the mouth, while HSV-2 is largely sexually transmitted through skin-to-skin contact causing genital sores.
However, the new estimates, published online today in PLoS One, highlight that HSV-1 is also an "important" cause of genital herpes, WHO said in a news release.
They note that roughly 140 million people aged 15 to 49 years have genital HSV-1 infection, primarily in the Americas, Europe, and Western Pacific. "Fewer people in high-income countries are becoming infected with HSV-1 as children, likely due to better hygiene and living conditions, and instead are at risk of contracting it genitally through oral sex after they become sexually active," WHO said.