Varicella. Clinical Manifestations

PRIMARY INFECTION

Primary infection with VZV produces the well-known clinical syndrome of varicella or chickenpox. Low-grade fever may precede the development of the rash by 1 to 2 days. The characteristic rash involves lesions that appear in crops and proceed through a series of well-defined stages. The lesions start as erythematous macules, progress to vesiculation with the classic “dew drop on a rose petal” appearance, become pustular, and finally crust over. The hallmark of the varicella rash is the simultaneous presence of lesions of different stages. The rash tends to appear initially on the trunk, then spread to the face, neck, and extremities. Mucous membranes can be involved. The lesions are intensely pruritic. Systemic manifestations of illness usually are mild or absent. In immunocompetent children, new crops of lesions continue to appear for a few days; by 4 or 5 days, most are crusted over, and new lesions no longer form.

The severity of illness is related inversely to age. Primary varicella tends to be milder in young children, and teenagers and adults can become seriously ill. For reasons that remain to be elucidated, pregnancy seems to be an independent risk factor for severe varicella, although the association is controversial.

PRENATAL INFECTION

Prenatal infection is uncommon because most women of childbearing age are immune to varicella. Although rare, a congenital varicella syndrome occurs in nearly 2% of infants born to women who con-tract varicella in the first or second trimester of pregnancy. Congenital varicella syndrome is characterized by small infant size, cutaneous scarring, limb hypoplasia, microcephaly, cortical atrophy, chorioretinitis, cataracts, and other anomalies. Approximately 2% of infants who have intrauterine exposure to varicella develop zoster in infancy or early childhood.

PERINATAL INFECTION

Early studies suggested that the risk of death was as high as 31% among infants whose mothers had onset of primary varicella rash 0 to 4 days before birth. However, most believe that this statistic probably is inflated by selective reporting. The use of varicella zoster immune globulin (VZIG) in these infants has been associated with a markedly better prognosis. There is no evidence to suggest that postnatally acquired varicella infection is any more severe in neonates than it is in older infants.

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