Herpes simplex: Virus type 1 and 2

Clinic

Infections with herpes simplex virus (HSV), a DNA virus, are very common in worldwide human populations. Transmission takes place by droplet and aerosol infection from viruscontaining respiratory secretions or by contact. Primary Herpes simplex virus infections usually occur subclinically. Typical clinical symptoms are the appearance of blisters on skin and affected mucous membranes, which heal without scar formation. The virus persists in nerve ganglions and may be reactivated by suppression of the cellular immune system caused by various factors such as UV-radiation, stress, pregnancy or the presence of other diseases. Approximately a third of all cases are the result of reactivations.

There exist two different HSV types. HSV1 is mainly responsible for herpes labialis. The endemic infection rate in adults is approximately 90%. HSV2, commonly responsible for herpes genitalis, is transmitted mainly by sexual intercourse. Approximately 10-30% of the population (depending on social and economic status) show positive reactions with HSV2 antibodies. Recent clinical data indicate, that genital herpes is also caused by HSV1. Today Herpes genitalis, caused by HSV1 or HSV2, is one of the most frequent sexual transmitted diseases (STD). Though there is no difference in clinical appearance between HSV1 and HSV2, number of reactivation is higher with HSV2 than with HSV1. HSV2 is said to be a cofactor for cervix carcinoma, if there exists already a HPV high risk infection.

A neonatal HSV infection, most importantly HSV2, occurs during delivery when the newborn comes in contact with HSV2 while passing birth canal. This infection may cause severe damage to the neonate (Herpes neonatorum) with generalization of herpes and herpesencephalitis and is frequent, if the mother suffers from a primary herpes infection. Then infection rate is 50% and lethality for newborns is 70% (untreated).