Genital herpes is a sexually transmitted disease caused by a herpes virus characterized by painful blisters on the genital areas of men and women. It is spread person-to-person by sexual contact. It is not spread by toilet seats, doorknobs, swimming pools, hot tubs, or through the air. At present, there is no vaccine or cure.

There are eight kinds of human herpes viruses. Only two of these (herpes simplex types 1 and 2) cause genital herpes. Although it is commonly believed that herpes simplex virus type 1 causes only cold sores and herpes simplex virus type 2 causes only genital sores, this is not completely true. Both herpes virus type 1 and type 2 can cause herpes sores on either the lips or genitals.

Sometimes an active infection occurs without visible sores. An infected person can therefore spread herpes virus to other people without knowing it. The initial infection, known as the...