Herpes simplex virus (synonyms: inflammation caused by herpes simplex; genital herpes; HSV-1; HSV-2; genital herpes; herpes simplex type 1; herpes simplex type 2; herpes simplex labialis; herpes simplex recidivans in loco; herpes infection; herpesvirus infection; herpesvirus disease; labial herpes; recurrent herpes simplex; ICD-10-GM B00.-: Infections caused by herpes viruses [Herpes simplex]) is a pathogen from the group of DNA viruses, from the family Herpesviridae. In humans, the virus causes skin and mucous membrane rashes. A distinction is made between the following types of herpes simplex viruses:
- Herpes simplex virus type 1 (HSV-1) – so-called “oral strain”.
- Herpes simplex virus type 2 (HSV-2) – so-called “genital strain”.
Herpes simplex virus type 1 predominantly causes herpes labialis (“lip herpes”) and various other infections in the head area. This can lead to blisters on the lip (herpes labialis), nose (herpes nasalis), cheek (herpes buccalis, herpes facialis), eyelid or other body parts (herpes corporis). Herpes simplex virus type 2 predominantly causes genital herpes and herpes neonatorum (neonatal herpes).Meanwhile, the proportion of HSV-1 and HSV-2 in genital infections is almost equal. Humans currently represent the only relevant pathogen reservoir. Occurrence: Infection occurs worldwide. The contagiousness of the herpes simplex virus type 1 is very high. The infection rate is over 90% of the population (in Germany). The transmission (infection route) of the HSV-1 type occurs orally through saliva (droplet infection) and as a smear infection, while the HSV-2 type is transmitted sexually and perinatally (during birth), as a so-called smear infection. In acute infection of the pregnant woman, transplacental transmission to the fetus is possible in rare cases.Neo-/postnatal transmission to the fetus is possible via skin contact in herpes labialis by smear infection.Herpes simplex viruses can also be transmitted by oral sex. The entry of the pathogen occurs parenterally (the pathogen does not penetrate through the intestine), i.e. in this case, it enters the body through the skin (slightly injured skin; percutaneous infection) and through the mucous membranes (permucous infection). The incubation period (time from infection to onset of disease) for primary infection with HSV-1 is usually between 2-12 days and for primary infection with HSV-2 between 3-7 days (herpes neonatorum up to 17 days). Peak incidence: herpes simplex virus type 1 (HSV-1) occurs in childhood. In adulthood, more than about 90% of the population (in Germany) is infected. Seroprevalence (percentage of patients tested serologically positive): Infection with herpes simplex virus type 2 (HSV-2) begins after puberty. In adulthood, 10-30% of the population (worldwide) is infected. The seroprevalence in women of childbearing age is reported to be 82% for HSV-1 and 18% for HSV-2. The duration of infectivity (contagiousness) is as long as vesicles appear; however, virus transmission is also possible in the symptom-free phase. Course and prognosis: Herpes simplex virus type 1 (HSV-1): A cold sore episode lasts about 7-10 days if untreated. Herpes labialis occurs recurrently (recurring) in about one-third of people. Herpes simplex virus type 2 (HSV-2): In more than 90% of cases, the primary infection is asymptomatic (without symptoms). In otherwise healthy individuals, the course of infection is favorable and the disease heals spontaneously (on its own). In approximately 85% of all patients, primary genital herpes is followed by symptomatic recurrence (recurrence of the disease).In maternal (mother’s) primary infection in the last 4 weeks before birth, the neonatal risk of infection (of the newborn) is about 40-50%; in the first trimester, the neonatal risk of infection is only 1%. In children and people with immunodeficiency (immune deficiency), the infection can spread to the entire body (herpes sepsis) and may become life-threatening. Vaccination: A vaccination against herpes simplex viruses is not yet available, but is under development. Note: For details on herpes labialis or herpes genitalis, see the disease of the same name.
