Global and Regional Estimates of Prevalent and Incident Herpes Simplex Virus Type 1 Infections in 2012.
BACKGROUND
Herpes simplex virus type 1 (HSV-1) commonly causes orolabial ulcers, while HSV-2 commonly causes genital ulcers. However, HSV-1 is an increasing cause of genital infection. Previously, the World Health Organization estimated the global burden of HSV-2 for 2003 and for 2012. The global burden of HSV-1 has not been estimated.


METHODS
We fitted a constant-incidence model to pooled HSV-1 prevalence data from literature searches for 6 World Health Organization regions and used 2012 population data to derive global numbers of 0-49-year-olds with prevalent and incident HSV-1 infection. To estimate genital HSV-1, we applied values for the proportion of incident infections that are genital.


RESULTS
We estimated that 3709 million people (range: 3440-3878 million) aged 0-49 years had prevalent HSV-1 infection in 2012 (67%), with highest prevalence in Africa, South-East Asia and Western Pacific. Assuming 50% of incident infections among 15-49-year-olds are genital, an estimated 140 million (range: 67-212 million) people had prevalent genital HSV-1 infection, most of which occurred in the Americas, Europe and Western Pacific.


CONCLUSIONS
The global burden of HSV-1 infection is huge. Genital HSV-1 burden can be substantial but varies widely by region. Future control efforts, including development of HSV vaccines, should consider the epidemiology of HSV-1 in addition to HSV-2, and especially the relative contribution of HSV-1 to genital infection.
School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Katharine J
KJ
Looker
Department of Laboratory Medicine, University of Washington, Seattle, Washington, United States of America.
Amalia S
AS
Magaret
School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Margaret T
MT
May
School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Katherine M E
KM
Turner
School of Social and Community Medicine, University of Bristol, Bristol, United Kingdom.
Peter
P
Vickerman
Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland.
Sami L
SL
Gottlieb
Department of Reproductive Health and Research, World Health Organization, Geneva, Switzerland.
Lori M
LM
Newman
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006561:Herpes Simplex / Q000453:epidemiology* / Q000517:prevention & control / Q000821:virology; D018259:Herpesvirus 1, Human / Q000276:immunology / Q000472:pathogenicity*; D018258:Herpesvirus 2, Human / Q000276:immunology / Q000472:pathogenicity; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult