Zoster begins with pain and an erythematous maculopapular, then vesicular, rash in a dermatomal distribution. Adjoining dermatomes can be involved, and a few crops of vesicles are sometimes scattered outside the primary eruption. During the course of 1 week, the rash becomes pustular and then ulcerates and crusts. Healing occurs within weeks and sometimes results in scarring. VZV can be cultured from the blister fluid but may not survive in transport media. Most practical is to scrape the base of a new vesicle and apply the scrapings to a glass slide for DFA testing, which is sensitive and specific. PCR of vesicular fluid can also be used.
Differential:
Eye involvement is most common when accompanied by vesicles on the side or tip of the nose, meaning involvement by the nasocilliary branch of V-1 (Hutchinson’s sign). Eye involvement presents clinically with a painful red eye most commonly caused by corneal keratitis and/or uveitis (can cause chronic inflammation, scarring).
The incidence of zoster increases with age, although children who have had varicella during the first year of life (or in utero) are at increased risk of developing zoster. The incidence of zoster is less after varicella vaccination than after natural infection. Zoster in children is frequently mild, postzoster neuralgia rarely if ever occurs, and antiviral therapy is usually not needed. In a previously normal child with zoster, if the history and physical examination are normal, a laboratory search for occult immunodeficiency or malignancy is not needed.
Exposure of an immune individual to varicella or zoster should not result in zoster. In fact it boosts cellular immunity to varicella and may prevent zoster. "Outbreaks" can be explained by recognition artifact, i.e. after one case is diagnosed, it becomes more common to diagnose other cases.
PIDJ Volume 23(5) May 2004 pp 451-457 Feder, Henry M