Varicella-zoster virus: overview and clinical manifestations.

Varicella-zoster virus (VZV) is a human pathogen that has probably infected humans since prehistoric times. Varicella-zoster virus causes chickenpox in childhood (varicella), and establishes latency in sensory ganglia after the primary infection. Varicella-zoster virus may reemerge later in life, taking advantage of the decline in immune function that occurs with aging. Varicella-zoster virus reactivation causes herpes zoster, commonly known as shingles. The incidence of herpes zoster increases with advancing age. Severe pain is the major cause of acute and chronic morbidity in patients with herpes zoster. Fortunately, the acute phase is self-limiting and transient. However, chronic and often debilitating pain may persist after the lesions have healed and is referred to as postherpetic neuralgia (PHN), the most common complication of herpes zoster. Similar to acute herpes zoster, the incidence of PHN increases dramatically with age.