Genital herpes simplex virus type 1 infection: a thoroughly modern disease

Recently, a previously uncommon sexually transmissible infection (STI) has begun to dominate the statistics. A large Victorian laboratory reported that genital isolates of herpes simplex virus type 1 (HSV-1) now outnumber HSV-2 isolates in patients under the age of 20 years: 77.3% of HSV isolates in this age group were HSV-1. Overall, the percentage of genital isolates that were HSV-1 had risen from 15.8% in 1980 to 34.9% in 2003. At the Sydney Sexual Health Centre in 2004, 50% of clinical first episode genital herpes was attributable to HSV-1, and the proportion had been increasing for many years (unpublished data). This is a trend that is being seen throughout the industrialised world.