According to the first WHO global estimate of global herpes simplex virus type 1 infection, published today in the journal PLOSONE, more than 3.7 billion people under the age of 50 (67% of the population) are infected with herpes simplex virus type 1.
Herpes simplex viruses are divided into two groups: herpes simplex virus type 1 and herpes simplex virus type 2. herpes simplex virus type 1 and herpes simplex virus type 2 are highly infectious and incurable. herpes simplex virus type 1 is transmitted primarily through mouth-to-mouth contact, causing herpes of the mouth and lips around the mouth in most cases. herpes simplex virus type 2 is almost exclusively sexually transmitted through skin-to-skin contact, causing genital herpes. genital herpes.
And new estimates emphasize that herpes simplex virus type 1 is also an important cause of genital herpes. Approximately 140 million persons aged 15-49 years are infected with herpes simplex virus type 1 genital infections, mainly in the Americas, Europe and the Western Pacific. While the number of people infected with herpes simplex virus type 1 in high-income countries has tended to decrease, possibly due to improved sanitation and housing conditions, children are at risk of genital infection through oral sex as they become sexually active.
Large numbers of genital infections.
WHO estimated in January of this year that 417 million people aged 15 to 49 years are infected with herpes simplex virus type 2, which can cause genital herpes. Taken together, the estimates suggest that more than 500 million people aged 15-49 years have genital infections caused by herpes simplex virus type 1 or type 2.
”It is critical to have access to education and information on both types of herpes as well as sexually transmitted infections so that young people have health protection before they become sexually active.”
Dr. MarleenTemmerman, Director of WHO’s Division of Reproductive Health and Research
”The new estimates underscore the urgent need for countries to improve data collection for herpes simplex virus and sexually transmitted infections in general,” said Dr. Temmerman.
In the absence of a permanent cure for both herpes simplex virus types 1 and 2, WHO and partners are working to accelerate the development of herpes simplex virus vaccines and topical microbicides, which will be critical to preventing the emergence of these infections in the future. Research is underway on several candidate vaccines and microbicides.
Regional infection estimates.
Estimates of herpes simplex virus type 1 prevalence among persons aged 0-49 years, by region, 2012.
Americas: 178 million females (49%), 142 million males (39%)
Africa: 350 million females (87%), 355 million males (87%)
Eastern Mediterranean: 188 million women (75%), 202 million men (75%)
Europe: 207 million women (69%), 187 million men (61%)
Southeast Asia: 432 million females (59%), 458 million males (58%)
Western Pacific: 488 million females (74%), 521 million males (73%)
Estimated number of new herpes simplex virus type 1 infections among persons aged 0-49 years in 2012.
Americas: 6 million females, 5 million males
Africa: 17 million females, 18 million males
Eastern Mediterranean: 6 million females, 7 million males
Europe: 5 million females, 5 million males
Southeast Asia: 13 million females, 14 million males
Western Pacific: 11 million females, 12 million males
Disease symptoms.
Herpes is a lifelong infection, often with mild or no symptoms, but can be detected by the presence of antibodies to herpes simplex virus type 1 or herpes simplex virus type 2 in the blood. It is difficult to determine the percentage of people with symptomatic herpes simplex virus infection in the world because symptoms may be mild or not be considered herpes at all. In the United States of America, approximately 15% of people with herpes simplex virus type 2 infection report having a previous genital herpes diagnosis.
When genital herpes symptoms do occur, they take the form of one or more painful genital or anal blisters or ulcers. Herpes symptoms can be treated with antiviral medications, but symptoms may reappear after the first episode. Recurrence of genital herpes caused by herpes simplex virus type 1 is much less frequent overall than with herpes simplex virus type 2.
Transmission of the herpes simplex virus most often occurs in the absence of symptoms. The virus can have a significant negative impact on the mental health and personal relationships of infected individuals.
Patients who present with symptoms of orofacial herpes may face social stigma and may experience psychological distress as a result. Persons with a weak immune system, such as those in the late stages of HIV infection, may experience more severe symptoms and a higher frequency of recurrence. In rarer cases, herpes simplex virus type 1 infection can also lead to more serious complications such as encephalitis or eye disease.
WHO is currently developing a global health sector strategy for sexually transmitted infections that includes herpes simplex virus type 1 and herpes simplex virus type 2. When completed, the strategy will be submitted for consideration at the 69th World Health Assembly in 2016.