Herpes: A family of viruses. Herpes also refers to infection with one of the human herpesviruses, especially herpes simplex types 1 and 2.
Herpes simplex type 1, also known as human herpesvirus 1 (HHV-1), causes cold sores and fever blisters in the mouth and around it. Here is a depiction of a typical fever blister on the lip caused by HHV-1:
Herpes simplex type 2, also known as human herpesvirus 1 (HHV-1), causes genital herpes, a sexually transmitted disease (STD). Genital herpes is characterized by sores in the genital area.
Both herpes simplex types 1 and 2 are capable of causing systemic disease including encephalitis (infection of the brain) in someone who is immunodeficient.
The treatment of infection with herpes simplex infections is by topical or oral anti-viral medication.