ATLANTA (CBS Atlanta) — A new study finds that more than 3.7 billion people under the age of 50 have herpes, and that the main culprit could be the rise in oral sex.

Researchers at the University of Bristol believe that more people are being infected with herpes type one due to oral sex.

“It is likely that in higher-income settings, fewer people are becoming infected with HSV-1 as children,” lead Dr. Katharine Looker of the School of Social and Community Medicine told the Bristol Post. “At the same time, oral sex is now common. This means that more people are able to be infected with HSV-1 genitally after becoming sexually active.”

Herpes is categorized into two types – HSV-1 and HSV-2. The first one is transmitted through kissing and causes cold sores around the mouth, while the second one is transmitted through skin-to-skin contact and causes genital sores.

More than 500 million people between the ages of 15 and 49 have a genital infection due to herpes, according to experts.

The Centers for Disease Control and Prevention says there is no cure for herpes.

The study was published in a journal compiled by the World Health Organization.