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(Corrects age range in third paragraph to 15-49 from 17-49)
By Tom Miles
GENEVA, Oct 28 (Reuters) - Two-thirds of the world'spopulation under 50 have the highly infectious herpes virus thatcauses cold sores around the mouth, the World HealthOrganization said on Wednesday, in its first estimate of globalprevalence of the disease.
More than 3.7 billion people under the age of 50 suffer fromthe herpes simplex virus type 1 (HSV-1), usually after catchingit in childhood, according to a the WHO study.
That is in addition to 417 million people in the 15-49 agerange who have the other form of the disease, HSV-2, whichcauses genital herpes.
HSV-1 normally causes mouth ulcers rather than genitalinfection, but it is becoming an increasing cause of genitalinfection too, mainly in rich countries.
That is because improved hygiene in rich countries islowering HSV-1 infection rates in childhood, leaving youngpeople more at risk of catching it via oral sex when they becomesexually active.
HSV-2 can increase the risk of catching and spreading HIV,the disease that causes AIDS. Little is known about any linkbetween HSV-1 and HIV/AIDS, although it can lead to otherserious complications such as encephalitis.
"We really need to accelerate the development of vaccinesagainst herpes simplex virus, and if a vaccine designed toprevent HSV-2 infection also prevented HSV-1, it would have farreaching benefits," said Sami Gottlieb, a WHO medical officer.
Nathalie Broutet, also a WHO medical officer, said the U.S.National Institutes of Health and companies includingGlaxoSmithKline Plc were involved in trials to determinewhether a therapeutic or preventative vaccine was preferable.
Gottlieb said GSK had previously abandoned a vaccine trialafter finding the product was not effective against HSV-2,although it did show some efficacy against HSV-1.
"That was interesting and promising and gave a proof ofconcept that these vaccines can be developed. There's a lot ofwork ongoing and we're hopeful that we'll have an HSV vaccine inthe future," she said.
Several phase-1 and phase-2 trials were underway, she said.Genocea Biosciences Inc recently dropped work on apneumonia vaccine in favour of its more promising work ongenital herpes. (Reporting by Tom Miles; Editing by Gareth Jones)
