Chickenpox and shingles

Chickenpox and shingles

Chickenpox (varicella) and shingles (herpes zoster) are two different forms of disease caused by the varicella-zoster virus, which is a deoxyribonucleic acid (DNA) virus closely related to herpes simplex and Epstein-Barr viruses. Initial infection causes varicella, a common childhood infection characterized by fever, malaise, and a rash consisting of dozens to hundreds of small fluid-filled lesions (vesicles) that are individually surrounded by reddened skin. Successive crops of lesions appear that eventually ulcerate and crust over during the two-week course of the disease. The virus is spread from person to person by the highly infectious respiratory secretions and lesion drainage. Varicella is rarely a serious disease in normal children but can be severe in immunocompromised individuals or in the rare adult who escaped childhood infection. Primary infection results in immunity to a new varicella-zoster virus, but the original virus lies dormant in nerve ganglia cells. See Epstein-Barr virus, Herpes

At some time in their life, approximately 10% of the population suffers subsequent reactivation of latent virus, which spreads to the skin overlying the affected nerve and causes a localized eruption of vesicles called herpes zoster. The vesicles are similar in appearance and in infectiousness to varicella lesions. This syndrome is usually well tolerated, although elderly persons may develop chronic pain at the site of reactivation. Herpes zoster in immunocompromised individuals may be prolonged or may disseminate to vital organs.

Varicella or herpes zoster in a normal host is self-limited and does not typically require antiviral therapy. In individuals with underlying immune disorders, treatment with the antiviral drug acyclovir decreases the duration and severity of disease. See Animal virus