Herpes Simplex: Viral disease caused by the herpes simplex virus

The herpes simplex virus (HSV) causes two common diseases. Both diseases have painful, watery blisters in the skin or mucous membranes (such as the mouth or lips) or on the genitals.

An infection on the lips is commonly known as a cold sore or fever blister. A cold sore is not the same as a canker sore, which appears inside the mouth and is caused by something else.

The disease is contagious, especially when it is active. Contagious means that it can spread from one person to another. There is no cure for this disease. This means that it cannot be stopped, once a person has got it. When a person has got the disease, he or she will get outbreaks from time to time. There are drugs that can make these outbreaks shorter, for many people. These antiviral drugs stop the virus from spreading. They will shorten the time people show symptoms.

The two types of herpes virus are known as simplex virus, type 1 (HSV-1) and type 2 (HSV-2). HSV-1 usually causes infections around the mouth. HSV-2 more commonly causes genital infections. Viruses are transmitted through body fluids, or lesions in the skin. Transmission can also occur, when there are no symptoms. Genital herpes is classified as a sexually transmitted infection. It may be spread to a baby during childbirth. Herpes outbreaks can occur, because of decreased immune function, stress, and sunlight exposure.

Usually, herpes is diagnosed based on the symptoms. There are tests that can confirm this diagnosis. Testing the blood for antibodies against the virus can confirm a previous infection but will be negative in new infections.

Herpes is very common. Worldwide rates of either HSV-1 or HSV-2 are between 60% and 95% in adults. Most people get HSV-1 when they are children. Since there is no cure for either HSV-1 or HSV-2, more people get it as they get older. Rates of HSV-1 are between 70% and 80% in poorer people and 40% to 60% in richer people. About 536 million people worldwide (16% of the population) were infected with HSV-2 as of 2003. It is more common among women and in developing countries. Most people with HSV-2 do not know that they are infected.