Oral herpes is a mouth infection that is caused by a virus called herpes simplex. The symptoms appear in the form of lip sores, often colloquially referred to as cold sores, and, in some cases, sores on the mucous membranes of the oral cavity. These mouth sores are usually blisters filled with fluid, which eventually burst.
The herpes virus is extremely common; medical professionals state that the percentage of people who have experienced some form of herpes infection by the time they reach adulthood is close to 100 %. There are in fact two different types of the herpes simplex virus (HSV), called HSV-1 and HSV-2 respectively. HSV-1 is by far the more common of the two viruses, but they are very similar, causing the same symptoms in the infected person. Both types of the virus can also cause the related infection, genital herpes.
In addition to the main symptoms of lip sores and oral blisters, sometimes additional symptoms are experienced during an oral herpes infection. These symptoms may include swollen gums, fever, headache, and dehydration. Young children are particularly prone to suffering from these unpleasant symptoms, and often experience significant pain in the mouth, which can make it difficult to eat.
Oral herpes is very infectious. It can be transmitted by kissing other skin contact, or by the sharing of items that come into contact with the mouth, such as a toothbrush or lipstick. In addition, the virus can be passed from the mouth to the genitals, or vice versa, during oral sex.
When a person becomes infected with oral herpes, the virus normally proceeds through three distinct stages. The first time a person is infected, the viruses penetrate the membranes of the mouth and begin to reproduce. This is called a primary infection, and may be accompanied by sores and other symptoms. Alternatively, it may occur without any symptoms, in which case it is called an asymptomatic infection.
In the second stage of the infection, the virus migrates from the mouth to the nervous tissue in the spine. Here, the virus continues to reproduce for a period, and then becomes inactive. This stage of the infection is called latency, and the infected person will typically continue to be a host to the virus on a permanent basis.
Herpes sores appear from time to time. This usually happens when the infected person becomes stressed, either physically or mentally. This stage is called recurrence, and is likely to occur repeatedly, as the virus alternates between latency and activity.