The Herpes Simplex Virus (HSV) 1 & 2, IgG test is used to determine whether a person has currently or previously had the highly contagious Herpes infection caused by HSV. Oral herpes is caused by the HSV-1 virus and can be contracted through oral contact. Cold sores and blisters appear around the mouth and on the face. While HSV-2 causes genital herpes, which is spread through sex and is characterised by sores in the genital region, it is not contagious. An early HSV infection can be found via a blood test known as a herpes IgM (immunoglobulin M) test. HSV is an infection that can cause lip or genital ulcers.