To screen for or diagnose infection with the herpes simplex virus. Simplex 1 is often referred to as cold sores or fever blisters. They occur mostly on the face and look like tiny, fluid-filled blisters. They can also develop as wounds on the skin. It can be transmitted by kissing, sharing eating utensils, or by sharing towels. Herpes Simplex 2 usually results in sores on the buttocks, penis, vagina, or cervix. Sexual intercourse is the most frequent means of getting Simplex 2.