Most genital herpes is caused by infection of herpes simplex virus type 2 (HSV-2). Herpes simplex virus type 1 (HSV-1) is more often the cause of cold sores, but it can also be a cause of genital herpes.Once the virus enters through the skin, it travels along nerve paths.enital herpes is caused by the herpes simplex virus, or HSV. Genital herpes often affects the 20-24 year old age group, with around 30,000 new cases diagnosed in sexual health clinics in the UK each year.