Herpes simplex Health Article

Definition

Herpes simplex is a viral infection that mainly affects the mouth or genital area.

Causes, incidence, and risk factors

There are two strains of herpes simplex viruses:

• Herpes simplex virus type 1 (HSV-1) is usually associated with infections of the lips, mouth, and face. It is the most common herpes simplex virus and many people develop it in childhood. HSV-1 often causes sores (lesions) inside the mouth, such as cold sores (fever blisters), or infection of the eye (especially the conjunctiva and cornea). It can also lead to infection of the lining of the brain (meningoencephalitis). It is transmitted by contact with infected saliva. By adulthood, 30 - 90% of people will have antibodies to HSV-1. The likelihood of childhood infection is higher among those with lower socioeconomic status.
• Herpes simplex virus 2 (HSV-2) is usually, but not always, sexually transmitted. Symptoms include genital ulcers or sores. However, some people with HSV-2 have no symptoms. Up to 30% of adults in the U.S. have antibodies against HSV-2. Cross-infection of type 1 and 2 viruses may occur from oral-genital contact. That is, you can get genital herpes on your mouth, and oral herpes on your genital area.

A finger infection, called herpetic whitlow, is another form of HSV infection. It usually affects health care providers who are exposed to saliva during procedures. Sometimes, young children also can get the disease.

HSV can infect a fetus and cause abnormalities. A mother who is infected with HSV may transmit the virus to her newborn during vaginal delivery, especially if the mother has an active infection at the time of delivery. However, 60 - 80% of HSV infections acquired by newborns occur in women who do NOT have symptoms of HSV infection or a history of genital HSV infection.

It's possible for the virus to be transmitted even when there are no symptoms or visible sores. Two-thirds of people with genital HSV infection have recurrences of their symptoms, and one-third have three or more recurrences (outbreaks) per year.

HSV is never eliminated from the body, but stays dormant and can reactivate, causing symptoms.