[Herpes simplex virus type 1 and 2 in Switzerland]

A worldwide increase in the incidence of genital herpes infections has been described in recent years. Transmission of the herpes simplex virus type 2 (HSV-2) by asymptomatic seropositive subjects is considered to be a relevant mode of infection. The seroprevalence of HSV-2 varies considerably between different populations. In Europe, data are scarce and the epidemiological situation in Switzerland is unknown. In 1997 we performed serological examinations in 151 adult volunteers (87% between 20 and 49 years of age) of a low-risk population from the region of Basel with no history of genital herpes or any other sexually transmitted disease. The overall seroprevalence of HSV-1 was 77% and an annual seroconversion rate of 4.6% (95% CI: 3.8-5.6) was estimated for both sexes. Of the 51 subjects with no symptoms of orolabial herpes, 25 (49%) proved to be HSV-1 seropositive. In contrast, of 91 patients with symptoms of orolabial herpes, 90 (97%) had serum antibodies against HSV-1. The seroprevalence of HSV-2 was 14.6% for women (n = 89) and 8.1% for men (n = 62). The annual seroconversion rate was estimated to be 0.61% (95% CI: 0.14-1.4) for women and 0.49% (95% CI: 0.09-1.4) for men for the period after 1985 (when "safer sex" and the use of condoms were promoted). Our results indicate the significance of herpes simplex virus type 2 infections in Switzerland. More detailed studies are needed to describe the epidemiology of HSV-2 infections more reliably, especially in view of progress in the development of vaccines against HSV infections.