Herpes virus type 3 is also known as varicella-zoster virus which causes chicken pox. This virus can also lead to a recurrent infection called herpes zoster or shingles. It occurs when the virus becomes reactivated after causing chicken pox and infects the skin. So if you have had chicken pox as a child, you may get shingles afterwards. Shingles and chicken pox cause blisters anywhere on the body. They are contagious and can be spread by direct contact with fluid from the blisters.
The causes of reactivation are uncertain, but several potential triggers have been documented. A 2009 study showed the protein VP16 plays a key role in reactivation of the dormant virus. Changes in the immune system during menstruation may play a role in HSV-1 reactivation. Concurrent infections, such as viral upper respiratory tract infection or other febrile diseases, can cause outbreaks. Reactivation due to other infections is the likely source of the historic terms 'cold sore' and 'fever blister'.