The test is used in two ways:

• to detect the presence of the herpes simplex virus, and
• to screen sexually active people.

Your doctor may use the test if you have a blister or vesicle on your genitals or mouth. Any sore in the genital area can be a symptom of a serious disease and should be tested.

A positive culture test on a scraping from a vesicle indicates an active infection.

There are two types of herpes simplex virus (HSV): 

• HSV-1 typically causes fever blisters or cold sores on the mouth or face, which is called oral herpes. 
• HSV-2 typically causes vesicles in the genital area and is called genital herpes.

The type of infection depends on the location of the virus more than on the type of virus—each type can cause either genital or oral infections if that is where it is contracted.

Blood tests are available to diagnose a herpes infection; however, they are not completely reliable for differentiating between HSV1 and HSV2. Most doctors rely on visual inspection of any lesions and culture of the scrapings taken from the infected area. Once the virus is grown in culture, the herpes virus can be typed using specific antisera for HSV 1 and HSV 2.

Herpes can make people more susceptible to HIV infection and can make people who have HIV more infectious to others.