The incubation period for HSV infection is usually 2-12 days. The onset may be either acute or gradual. Quite often the primary infection isn’t noticed by the patient and the disease becomes recurrent. Relapses may occur 2-3 times a year and extremely rarely 1-2 times in 10 years. Relapses tend to develop on the background of a weakening immunity, that’s why clinical manifestations of herpes are frequently accompanied by severe acute respiratory syndrome, pneumonia, and other acute infections.