Causes
In children the primary source of infection is the orofacial area, and it is commonly inferred that the virus (in this case commonly HSV-1) is transferred by the chewing or sucking of fingers or thumbs.
In adults it is more common for the primary source to be the genital region, with a corresponding preponderance of HSV-2. It is also seen in adult health care workers such as dentists because of increased exposure to the herpes virus.
Read more about this topic: Herpetic Whitlow