The term herpes is used colloquially in English to refer to a (usually) sexually transmitted, double-stranded DNA virus called herpes simplex virus (HSV) type 2 (also known as human herpesvirus 2, or HHV2). This virus is closely related to herpes simplex virus type 1 (HSV-1 or HHV1), which is the cause of common nonsexually transmitted cold sores. These two viruses are among the eight members of the herpes virus family that infect humans and cause a variety of illnesses such as cold sores, brain infection (encephalitis), chickenpox, various cancers and up to 70% of the cases of Bell's palsy (facial paralysis)