Herpes zoster is caused by the same virus that causes varicella, Herpesvirus varicellae.
A primary infection with varicella does not result in its complete removal from the body. Some virus remains in nerve ganglia. Activation of that virus results in herpes zoster, with lesions occurring in the dermatome supplied by that particular nerve. Grouped vesicles, each quite typical of a solitary chickenpox vesicle, develop in that dermatome.
More than ten ectopic vesicles outside of the dermatome of involvement, and the immediately adjacent dermatomes, is generalized herpes zoster. Generalized herpes zoster connotes a decreased immune response.
Disseminated herpes zoster is herpes zoster involving internal organs to a clinically obvious extent. Disseminated herpes zoster is a potentially fatal disease.
- Localized herpes zoster does not require specific antiviral treatment.
There is some evidence to suggest that oral acyclovir is useful at reducing the post-herpetic neuralgia which results from scarring around the cutaneous nerve endings.
Early and aggressive treatment is necessary to prevent the post herpetic neuralgia.
- Generalized and disseminated herpes zoster warrant treatment with oral or IV acyclovir.
Unless already obvious, investigation for an underlying cause of immune deficiency is warranted in individuals with the latter two forms of herpes zoster.
Local treatment measures may include wet to dry soaks to the eroded skin, tid to qid.
Post-herpetic neuralgia can respond to topical capsaicin cream qid for 6 weeks, or, alternatively to systemic agents such as pimozide or doxepin.