Cold Sore Health Article

Definition

A cold sore is a clear, fluid-filled blister, which often appears on the lips or nose. Cold sores, also referred to as fever blisters, are caused by a viral infection, herpes simplex virus Type 1 (HSV-1).

Description

Cold sores are painful, unsightly, and often recurrent. HSV-1 often occurs on the lower face but can occur on the genitals or buttocks. Though rarely fatal, HSV-1 can be serious if cold sores occur in newborns, the chronically ill, or the elderly.

Other names for cold sores are oral herpes, labial herpes, herpes labialis, and herpes febrilis. They are different from common canker sores because they usually are on the lips, whereas canker sores usually occur inside the mouth, on the tongue, or inside the cheeks. Cold sores rarely occur inside the mouth except during the initial episode.

While there are eight types of herpes viruses, cold sores are only caused by HSV-1 or herpes simplex virus Type 2 (HSV-2). 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 completely true. HSV-1 does appear on the genitals and sometimes on other areas of the body. Nurses and other health care workers have been known to get herpetic sores after the virus has entered a break in the skin of their fingers.

Oral herpes is very common. About 50-80% (some estimates are as high as 90%) of Americans are thought to carry antibodies for HSV-1. Most people who are exposed to HSV-1 become infected but only 10% of those people have symptoms, such as sores, and experience recurring outbreaks of the infection. Of the 50 million Americans thought to be infected with HSV-1, most acquired the virus when they were children and only about 5% are bothered enough by HSV-1 to consider it a medical problem.

Anyone can become infected by the herpes virus, and once a person is infected the virus remains latent for life. Herpes viruses are spread from person to person by direct skin-to-skin contact and, sometimes, by respiratory transmission (coughing or sneezing). The highest risk for spreading the virus is the time period beginning with the appearance of blisters and ending with scab formation. However, infected persons need not have visible blisters to spread the infection to others, since the virus may be present in the saliva without obvious oral lesions.

Viruses are different from bacteria. While bacteria are independent and can reproduce on their own, viruses enter human cells and force the cells to make more of the virus. The infected human cell is usually killed and releases thousands of new viruses. The cell death and resulting tissue damage causes the actual cold sores. In addition, the herpes virus can infect a cell and instead of making the cell produce new viruses, it hides inside the cells of the nervous system. This 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 which cause an active infection.

This process of latency and active infection is best understood by considering the cold sore cycle. An active infection is obvious because cold sores are present. The first infection is called the "primary" infection. This active infection is then controlled by the body's immune system and the sores heal. In between active infections the virus is latent. At some point in the future, latent viruses become activated and once again cause sores. These are called "recurrent" infections. Although it is not known what triggers the latent virus to activate, several conditions seem to bring on infections. These include stress, illness, tiredness, exposure to sunlight, menstruation, fever, and diet.