Proportion of herpes simplex virus (HSV) type 1 and type 2 among genital and extragenital HSV isolates.

Herpes simplex virus type 1 (HSV-1) has been associated with orofacial infections and HSV type 2 (HSV-2) with genital infections. This tropism of the virus seems to have changed and in clinical reports an increasing number of genital herpes infections caused by HSV-1 have been recognized. The aim of this study was to estimate the proportion of HSV-1 and HSV-2, respectively, among isolates from different anatomical sites typed in our laboratory during the years 1994-1998. Out of a total of 3,085 anogenital isolates, 29% were typed as HSV-1 and 71% as HSV-2. The highest prevalence of HSV-1 was registered among isolates from young women. Of 631 orofacial isolates, 4% were typed as HSV-2 and 96% as HSV-1. Of 69 finger/hand isolates, 54% were typed as HSV-1 and 46% as HSV-2, and of 95 isolates from other regions (abdomen, foot, etc.), 60% were typed as HSV-1 and 40% as HSV-2. It was found that HSV-2 was as common as HSV-1 in the extra-genital regions with the exception of the orofacial area, in which HSV-2 was seldom detected. Furthermore, the study showed an increasing proportion of HSV-1 among anogenital isolates during the study period. Taken together, these results suggest that a clear HSV type-related tropism might be limited to the permissiveness of the orofacial region for HSV-1, and that both serotypes may readily establish infections below the neck.