Wikipedia extract Herpes zoster, colloquially known as shingles, is the reactivation of varicella zoster virus (one of the Herpesviridae group), leading to a crop of painful blisters over the area of a dermatome. In Italy and in Malta, it is sometimes referred to as "St. Anthony's fire".

Prior to implementation of the universal varicella vaccination program in the U.S., incidence of shingles increased with advancing age. The incidence rate in children aged less than 10 years was approximately 70 cases/100,000 person-years, increasing to 550 cases/100,000 person-years among adults aged 50 to 59 years. Historically, it was thought that shingles incidence increased due to an age-related decline in immunity; however, recent studies [1] suggest that incidence of shingles is linked to the reduced frequency of periodic exogenous (outside) exposures to children with varicella (chickenpox) due to the increasing vaccination of that population. These exposures produced an immunologic boost that helped suppress the reactivation of shingles.

Shingles incidence is high in the elderly (over 60), as well as in any age group of immunocompromised patients. It affects some 1 million people per year in the United States and can involve excruciating pain. Many patients develop a painful condition called postherpetic neuralgia which is often difficult to manage.