The global epidemiology of herpes zoster.

Varicella-zoster virus (VZV) is a ubiquitous, highly neurotropic, exclusively human α-herpesvirus. Primary infection usually results in varicella (chickenpox), after which VZV becomes latent in neurons of cranial nerve ganglia, dorsal root ganglia, and autonomic ganglia along the entire neuraxis. As humans undergo a natural decline in cell-mediated immunity (CMI) to VZV with age, VZV frequently reactivates to produce zoster, characterized by maculopapular or vesicular rash and dermatomal-distribution pain. Pain and rash usually occur within days of each other. Pain is severe and often burning. Colorful descriptions of zoster exist worldwide. In Arabic, Hezam innar ( ) means belt of fire; in Hindi, Baoisayaa daga ( ) means big rash; in Norwegian, Helvetesild means Hell's fire (also described as a bell of roses from Hell); and in Spanish, Culebrilla means small snake.(1) The most common complication of zoster is postherpetic neuralgia (PHN), operationally defined as pain lasting for more than 90 days after rash. Zoster may be followed by multiple neurologic disorders (meningoencephalitis, myelitis, and vasculopathy, including VZV temporal arteritis) as well as ocular disease (acute or progressive outer retinal necrosis).