Cold Sore Health Article

Definition

Cold sores are small red blisters, filled with clear fluid, that form on the lip and around the mouth. Rarely, they form on the roof of the mouth. Cold sores are caused by the herpes simplex virus type 1 (HSV-1), which lives inside nerve tissue. Despite their name, cold sores have nothing to do with colds. The herpes simplex virus type 1 should not be confused with the herpes simplex virus type 2 (HSV-2), which most often causes genital herpes.

Description

There are eight different kinds of human herpes viruses. Only two of these, herpes simplex types 1 and 2, can cause cold sores. It is commonly believed that herpes simplex virus type 1 infects above the waist and herpes simplex virus type 2 infects below the waist. This is not true. Both herpes virus type 1 and type 2 can cause herpes lesions on the lips or genitals, but recurrent cold sores are almost always type 1.

The sores can appear within days or weeks or even years following the first exposure to the virus. The first time symptoms appear they are usually more intense than later outbreaks. For example, some children experience more pain at the blister site or even flu-like symptoms, including swollen glands, fever, or sore throat. Medical names for cold sores include oral herpes, labial herpes, herpes labialis, and herpes febrilis.

Transmission

Herpes simplex virus is transmitted by infected body fluids (such as saliva) when they contact breaks in another person's skin or mucous membranes. Newborns may become infected during delivery through an infected birth canal. HSV-1 can be passed to children by parents, nurses, and caregivers who fail to practice careful hand washing. Children with burns, eczema, or diaper rash or those who are immunosuppressed are highly susceptible to the herpes virus.

VIRUS VERSUS BACTERIA Viruses behave differently than bacteria. While bacteria are independent and can reproduce on their own, viruses enter human cells and force them to make more viruses. The infected human cell dies and releases thousands of new viruses. The cell death and resulting tissue damage causes the cold sores. In addition, the herpes virus can infect a cell, and instead of making the cell produce new viruses, it hides inside the cell and waits. The herpes virus hides in the nervous system. This action is called latency. A latent virus can wait inside the nervous system for days, months, or even years. At some future time, the virus "awakens" and causes the cell to produce thousands of new viruses that cause an active infection.

Latent and active infection is understood by considering the cold sore cycle. The first infection is the primary infection. The primary infection is controlled by the body's immune system and the sores heal. Between active infections, the virus is latent. At some point in the future, latent viruses become activated and once again cause sores or recurrent infections. Although it is unknown what triggers latent virus to activate, several conditions bring on infections. These include stress, illness, fever, fatigue, exposure to sunlight, menstruation, and diet.