In herpes labialis – colloquially called cold sores – (synonyms: Herpes simplex labialis; labial herpes; cold sore; febrile cold sore; cold sore; ICD-10-GM B00.1: Dermatitis vesicularis due to herpes viruses) is an infection with herpes simplex virus type 1 (HSV-1, human herpes virus) that affects the lips. Less commonly (but increasingly), herpes labialis is also caused by herpes simplex virus type 2 (HSV-2), which is considered the predominant causative agent of genital herpes (genital herpes).
The virus is from the Herpesviridae family. It is a pathogen from the group of DNA viruses.
The herpes simplex virus type 1 (HSV-1) mainly causes skin and mucous membrane infections on the upper body. However, it is also responsible for about 30% of cases of genital herpes.
Humans currently represent the only relevant pathogen reservoir.
Occurrence: The 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.Neo-/postnatal transmission to the fetus is possible via skin contact in the case of herpes labialis through smear infection.
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.
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. Infection with the herpes simplex virus type 2 (HSV-2) begins after puberty. In adulthood 10-30 % of the population (worldwide) are infected. The tendency is increasing.
The duration of infectivity is difficult to define: Herpes is contagious both during primary infection and during reactivation of dormant herpes viruses. It is treacherous that the classic symptoms of a herpes infection can be absent, i.e., no vesicles appear. In such cases, one speaks of a latent infection. Even in this phase, a high level of infectivity must be assumed, i.e. kissing, sharing glasses or cutlery is associated with a high risk of infection.In the typical course of a cold sore episode, the risk of infection decreases as soon as a crust is formed. Once the skin has healed, there is no longer any infectivity.
Course and prognosis:A cold sore episode consists of the following phases:
- Tingling and redness phase (day 0; duration: hours to a day).
- Vesicle phase: lip herpes becomes visible (day 1/2; duration: about 1 day).
- Open wound phase: erosions (superficial substance defects limited to the epidermis) or ulcerations (ulceration) (day 1/2; duration: about 1 day).
- Crusting phase: yellowish crusts (day 2/3; duration about 3 days).
- Decongestion phase (day 3; duration about 3-4 days).
- Healing phase (day 8; duration: about 2 days).
A cold sore episode lasts untreated about 7-10 days.Herpes labialis occurs recurrent (recurring) in about one-third of people.
Vaccination: a vaccine against herpes simplex virus is not yet available, but is in development.
