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Varicella (chickenpox) usually presents as two or three successive crops of diffuse, pruritic, delicate vesicles over several days. Individual lesions begins as faint erythematous macules that progess to edematous papules and then to vesicles that appear as "dewdrops on a rose petal" during 24-48 hours. The vesicles may then develop into pustules or moist crusts that dry and are shed leaving a shallow erosion. At any one time several stages of lesions can be observed concomitantly. Lesions tend to persist for about 1 week. Associated symptoms are mild and fever is usually low-grade. The disease is contagious via respiratory spread and contact with cutaneous lesions. The child is considered contagious from 2 to 4 days prior to the onset of lesions until all lesions have crusted.

Differential diagnosis

Varicella is diagnosed clinically through physical findings of the characterisitic lesions and through history of exposure. The differential includes HSV and hand-foot-and-mouth disease. A Tzanck smear can differentiate between hand-foot and mouth disease and varicella. A viral culture may be necessary to distinguish between HSV and varicella.

Pathophysiology

Varicella primary infection begins in the nasopharynx. After local replication, viremia seeds the reticuloenodthelial tissue. Secondary viremias causes dissemination to the skin and viscera. VZV then enters a dormant phase in the sensory ganglia where it can later erupt as herpes zoster.

Treatment

Symptomatic therapy with calamine lotion, wet dressings, soothing baths and oral antihistamines is the mainstay of therapy. Routine childhood vaccination is now recommended for children and adolescents who have not been infected. However, vaccinated patients may still experience a mild eruption. It is also important to observe for secondary bacterial infection and treat appropriately if it develops. Acyclovir may be used in patients expected to have a severe clinical course such as patients older than 12 years.