Causes
Genital herpes may be caused by 1 of 2 types of herpes virus: herpes simplex 1 (HSV-1) or herpes simplex 2 (HSV-2). These viruses can also infect the mouth, causing cold sores. Most cases of genital herpes are caused by HSV-2; however, HSV-1 may also be responsible. HSV-1 infection of the genitals is often caused by someone with cold sores performing oral-genital sex. HSV-2 infection of the mouth is often caused by someone performing oral-genital sex on someone with genital herpes.
The most common form of transmission is through sexual intercourse. The infection can cause blisters that shed viruses. People who have blisters are always infectious. If another person rubs against a blister, the virus can enter through the skin. However, not all people who are infected always produce skin blisters, and it is possible for the virus to be produced and spread even when there are no visible sores or blisters. Kissing can also transmit the virus if the mucous membranes of the mouth are infected.
The chances of catching genital herpes depend primarily on the number of sexual partners and whether or not protection was used. Women seem to be more easily infected than heterosexual men.
Herpes viruses can't be eliminated with today's medications. The virus infects a person's cells and remains with that person throughout their lifetime. Most of the time, the virus lies dormant in the nerve roots, but it can reactivate and move up to the skin surface from time to time, causing new breakouts of sores. These active sores can spread the disease. Sometimes, reactivations of the virus do not cause blister formation but the person remains contagious nonetheless, even though there are no visible sores. Therefore, an infected person with no visible symptoms, such as blisters or sores, can still infect or transmit the infection to an uninfected sexual partner. This is called asymptomatic shedding and causes a larger percentage of new genital herpes infections.