Genital herpes is a sexually transmitted disease caused by the herpes simplex virus.

What is going on in the body?

Genital herpes can be caused by either type of herpes simplex virus. Most cases are caused by herpes simplex virus type 2, or HSV 2. This type can also infect the person's mouth if he or she has oral sex with an infected partner. Some cases of genital herpes are caused by HSV 1, which usually causes cold sores on the lips.

The viruses infect nerve cells and remain in the body permanently after infection. When a person is first infected, blisters form on the genitals in what is called the primary episode. The blisters can then recur at any time in the future. The primary episode is usually more severe than the recurrences. Recurrences last about 10 days.

What are the causes and risks of the infection?

Herpes simplex virus infections are spread by close contact with a person who is actively shedding viral particles. The person usually has blisters during shedding, but the skin might look quite normal. Sexual intercourse is not necessary for transmission of genital herpes.