Bad news: you probably have herpes. Good news: you’re not alone.

A recent report from the World Health Organisation (WHO), published in PLOS ONE, has estimated two-thirds of people under 50 have the highly infectious herpes virus.

More precisely, 3.7 billion people under the age of 50 are thought to carry the herpes simplex virus type 1 (HSV-1). The virus, which is usually caught in childhood, causes cold sores around the mouth, although many people exhibit no symptoms.

However, most unnervingly, there’s been a rise in cases of HSV-1 causing genital herpes. Around 140 million people are thought to have a prevalent (existing) HSV-1 genital infection, most of which are in the Americas, Europe and Western Pacific. The report showed that developed countries have seen a rise in genital HSV-1 infections partly because of fewer childhood infections; those who already have HSV-1 orally are unlikely to get a subsequent infection of the genitals. Another factor is an apparent increase in popularity of oral sex, which can pass the virus from the mouth to the genitals.

In addition, the study found 417 million people between 17 and 49 years old have the HSV-2 strain, which causes genital herpes.

A herpes infection isn’t just an embarrassing red cornflake on your face or an even more awkwardly placed sore. HSV-2 can increase the risk of catching and spreading HIV and HSV-1 can lead to serious complications such as encephalitis, which causes inflammation of the brain.

After the first outbreak of herpes, the virus moves from the skin cells to nerve cells where it stays forever. It can lay dormant for years and years, however it can easily become active again.

Nathalie Broutet, a WHO medical officer, told Reuters the U.S. National Institutes of Health and pharmaceutical companies were in the process of trials to determine whether a therapeutic or preventative vaccine was preferable.

GSK, a British pharmaceutical company, was working on a vaccine, however it got abandoned after finding it wasn’t effective against HSV-2.

Sami Gottlieb, another WHO medical officer, told Reuters: "We really need to accelerate the development of vaccines against herpes simplex virus, and if a vaccine designed to prevent HSV-2 infection also prevented HSV-1, it would have far reaching benefits."

^{Main image credit: Yale Rosen/Flickr. (CC BY-SA 2.0).}