Herpes is a virus infection. There are 8 known herpes virus types with the herpes simplex virus type 1 being the one that triggers cold sore. The herpes virus is one of the most widespread viruses known today. 50-95% of the world’s population are infected with this virus.
The cold sore virus (herpes labialis) is usually transmitted through body fluids (mostly saliva). The primary infection usually occurs in early childhood. The infection, however, may not cause any symptoms for years while the virus lies dormant in the nerve ganglia – undetected by the immune system.
If the immune system’s response is weakened, the virus becomes active. It travels along the nerve pathways to the lips and starts to replicate. In most cases, this will cause a stretching and burning sensation in the lips.
This makes cold sore the unpleasant by-product of colds, sunburn, allergies or other infections.
Other factors that weaken the immune system are stress, disgust or great tension.
Apart from herpes simplex virus type 1, there is an increasing number of infections with herpes simplex virus type 2. Those are cases of a herpes infection below the waist, which are therefore also called genital herpes.
Another very unpleasant form of herpes is herpes zoster, also known as shingles.