Primary herpes simplex virus (HSV) infection is first infection with either herpes simplex virus-1 (HSV-1) or herpes simplex virus-2 (HSV-2) in individuals who do not have antibodies to either HSV-1 or HSV-2.
First episode-non primary infection is infection with either HSV-1 or HSV-2 in individuals who have previously existing antibodies against HSV-1 or HSV-2 respectively.
Recurrent HSV infection results from reactivation of latent virus. It is usually brought about by triggering factors eg UV light, immunosuppression.
Orolabial HSV disease is mostly caused by HSV-1 that occurs most commonly in children <5 years of age. It is transmitted through close contact with individuals who have active viral shedding.
Genital HSV disease is caused by HSV-2 that is the usual cause of herpes genitalis. It typically occurs in adults and transmitted through sexual contact.