Two-thirds of the world’s population under 50 have the highly infectious herpes virus that causes cold sores around the mouth, the World Health Organisation (WHO) said on Wednesday (28 October), in its first estimate of global prevalence of the disease.
More than 3.7 billion people under the age of 50 suffer from the herpes simplex virus type 1 (HSV-1), usually after catching it in childhood, according to a the WHO study.
That is in addition to 417 million people in the 17-49 age range who have the other form of the disease, HSV-2, which causes genital herpes.
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.
That is because improved hygiene in rich countries 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.
HSV-2 can increase the risk of catching and spreading HIV, the disease that causes AIDS. Little is known about any link between HSV-1 and HIV/AIDS, although it can lead to other serious complications such as encephalitis.
“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,” said Sami Gottlieb, a WHO medical officer.
Nathalie Broutet, also a WHO medical officer, said the US National Institutes of Health and companies including GlaxoSmithKline Plc were involved in trials to determine whether a therapeutic or preventative vaccine was preferable.
Gottlieb said GSK had previously abandoned a vaccine trial after 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 of concept that these vaccines can be developed. There’s a lot of work ongoing and we’re hopeful that we’ll have an HSV vaccine in the future,” she said.
Several phase-1 and phase-2 trials were underway, she said. Genocea Biosciences recently dropped work on a pneumonia vaccine in favor of its more promising work on genital herpes.
The WHO is currently working on the development of a global health sector strategy for sexually transmitted infections (STIs), including for HSV-1 and HSV-2, to be finalised for consideration at the 69th World Health Assembly in 2016.
Herpes is a lifelong infection, which often has mild or no symptoms but can be detected by the presence of antibodies for HSV-1 or HSV-2 in the blood, says the WHO. It is difficult to determine the proportion of HSV-infected people worldwide who have symptomatic disease, as symptoms may be mild or simply not recognised as herpes. In the United States of America, about 15% of persons with HSV-2 infection report a prior diagnosis of genital herpes.
People with orolabial herpes symptoms may face social stigma, and can experience psychological distress as a result. For persons with weak immune systems, such as those with advanced HIV infection, HSV-1 can have more severe symptoms and more frequent recurrences. Rarely, HSV-1 infection can also lead to more serious complications such as encephalitis or ocular disease.
- The World Health Organisation (WHO): Globally, an estimated two-thirds of the population under 50 are infected with herpes simplex virus type 1