Two-thirds of the world’s population under 50 have the highly infectious herpes simplex virus type 1 (HSV-1), according to a new World   Health Organization report published in the Public Library of Science journal PLoS ONE; it was the organization’s first estimate of the global prevalence of the disease, the Guardian reported.

HSV-1 normally causes mouth ulcers rather than genital infection, but it is becoming an increasing cause of genital infection too, mainly in rich countries, the Guardian claimed, adding that improved hygiene in more developed nations is lowering HSV-1 infection rates in childhood, leaving young people more at risk of catching it via oral sex when they become sexually active.

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“Access to education and information on both types of herpes and sexually transmitted infections is critical to protect young people’s health before they become sexually active,” Dr. Marleen Temmerman, director of WHO’s Department of Reproductive Health and Research, said in a news release quoted by US News and World Report.

In the Americas, the region with the lowest rates of infection, according to a related NBC report, the WHO estimates that 49 percent of women, or 178 million women, have HSV-1, and 39 percent of men, or 142 million, do. In Africa, 87 percent of people have HSV-1 while it's close to 60 percent in Southeast Asia, NBC also claimed.

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Nathalie Broutet, a WHO medical officer, said in the Guardian report that the US National Institutes of Health and companies including GlaxoSmithKline were involved in trials to determine whether a therapeutic or preventative vaccine was preferable.

“There’s a lot of work ongoing, and we’re hopeful that we’ll have an HSV vaccine in the future,” she was quoted by the Guardian.