Worldwide rates of either HSV-1 and/or HSV-2 are between 60 and 95% in adults.[9] HSV-1 is more common than HSV-2, with rates of both increasing as people age.[9] HSV-1 rates are between 70% and 80% in populations of low socioeconomic status and 40% to 60% in populations of improved socioeconomic status.[9] An estimated 536 million people or 16% of the population worldwide were infected with HSV-2 as of 2003 with greater rates among women and in those in the developing world.[10] Rates of infection are determined by the presence of antibodies against either viral species.[76]
In the US, 57.7% of the population is infected with HSV-1[77] and 16.2% are infected with HSV-2. Among those HSV-2-seropositive, only 18.9% were aware they were infected.[78] During 2005–2008, the prevalence of HSV-2 was 39.2% in blacks and 20.9% in women.[79]
The annual incidence in Canada of genital herpes due to HSV-1 and HSV-2 infection is not known (for a review of HSV-1/HSV-2 prevalence and incidence studies worldwide, see Smith and Robinson 2002). As many as one in seven Canadians [80] aged 14 to 59 may be infected with herpes simplex type 2 virus and more than 90 per cent of them may be unaware of their status, a new study suggests.[81] In the United States, it is estimated that about 1,640,000 HSV-2 seroconversions occur yearly (730,000 men and 910,000 women, or 8.4 per 1,000 persons).[82]
In British Columbia in 1999, the seroprevalence of HSV-2 antibody in leftover serum submitted for antenatal testing revealed a prevalence of 17.3%, ranging from 7.1% in women 15–19 years old to 28.2% in those 40–44 years.[83]
In Norway, a study published in 2000 found that 90% of genital initial infections were due to HSV-1.[84]
In Nova Scotia, 58.1% of 1,790 HSV isolates from genital lesion cultures in women were HSV-1; in men, 36.7% of 468 isolates were HSV-1.[85]'