Varicella, also called chickenpox, is a common, acute, and highly contagious infection caused by the herpesvirus varicella-zoster (V-Z), the same virus that, in its latent stage, causes herpes zoster (shingles). It can occur at any age, but it’s most common in 2- to 8-year-olds.
The varicella vaccine is effective in preventing varicella in up to 90% of recipients. The American Academy of Pediatrics recommends the vaccine for all children and for adolescents and adults who haven’t had varicella. It’s unknown how the vaccine affects shingles. (See Varicella vaccine, page 890.)
Congenital varicella may affect infants whose mothers had acute infections in their first or early second trimester. Neonatal infection is rare, probably due to transient maternal immunity. Second attacks are also rare.
Varicella is transmitted by direct contact (primarily with respiratory secretions; less often with skin lesions) and respiratory droplets. The incubation period lasts from 13 to 17 days. It’s probably communicable from 1 day before lesions erupt to 6 days after vesicles form (it’s most contagious in the early stages of eruption of skin lesions).
Most children recover completely, but potentially fatal complications may affect children receiving corticosteroids, antimetabolites, or other immunosuppressant agents, and those with leukemia, other neoplasms, or immunodeficiency disorders. Congenital and adult varicella may also have severe effects.
Varicella occurs worldwide and is endemic in large cities. Outbreaks occur sporadically, usually in areas with large groups of susceptible children. It affects all races and both sexes equally. Seasonal distribution varies; in temperate areas, incidence is higher during late autumn, winter, and spring.
Varicella produces distinctive signs and symptoms, notably a pruritic rash. During the prodromal phase, the patient has slight fever, malaise, and anorexia. Within 24 hours, the rash typically begins as crops of small, erythematous macules on the trunk or scalp that progress to papules and then clear vesicles on an erythematous base (the so-called “dewdrop on a rose petal”).
The vesicles become cloudy and break easily; then scabs form. The rash spreads to the face and, rarely, to the extremities. New vesicles continue to appear for 3 to 4 days, so the rash contains a combination of red papules, vesicles, and scabs in various stages. Occasionally, varicella also produces shallow ulcers on mucous membranes of the mouth, conjunctivae, and genitalia.
Congenital varicella causes hypoplastic deformity and scarring of a limb, retarded growth, and central nervous system and eye manifestations. In progressive varicella, an immunocompromised patient will have lesions and a high fever for more than 7 days.
CLINICAL TIP: Severe pruritus with varicella may provoke persistent scratching, which can lead to infection, scarring, impetigo, furuncles, and cellulitis. Rare complications include pneumonia, myocarditis, fulminating encephalitis (Reye’s syndrome), bleeding disorders, arthritis, nephritis, hepatitis, and acute myositis.
Varicella is diagnosed by characteristic clinical signs and usually doesn’t require laboratory tests. However, the virus can be isolated from vesicular fluid within the first 3 to 4 days of the rash. Serum contains antibodies 7 days after onset.
Patients must remain in strict isolation until all the vesicles and most of the scabs disappear (usually for 1 week after the onset of the rash). Children can go back to school, however, if just a few scabs remain because, at this stage, varicella is no longer contagious. Congenital varicella requires no isolation.
Generally, treatment consists of the following:
❑ local or systemic antipruritics
❑ cool bicarbonate of soda baths
❑ calamine lotion
❑ diphenhydramine or another antihistamine
❑ antibiotics if bacterial infection develops.
Salicylates are contraindicated because of their link to Reye’s syndrome.
Susceptible patients may need special treatment. When given up to 72 hours after exposure to varicella, V-Z immune globulin may provide passive immunity. Acyclovir may slow vesicle formation, speed skin healing, and control the systemic spread of infection.
❑ Teach the child and his family how to apply topical antipruritic medications correctly. Stress the importance of good hygiene.
❑ Tell the patient not to scratch the lesions. However, because the need to scratch may be overwhelming, parents should trim the child’s fingernails or tie mittens on his hands.
❑ Warn parents to watch for and immediately report signs of complications. Severe skin pain and burning may indicate a serious secondary infection and require prompt medical attention.
❑ To help prevent varicella, don’t admit a child exposed to varicella to a unit that contains children who receive immunosuppressant agents or who have leukemia or immunodeficiency disorders. A vulnerable child who has been exposed to varicella should receive V-Z immune globulin to lessen its severity.
Review other book chapters online related to Smallpox:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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Title: Handbook of Diseases Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2003 ISBN: 1-58255-266-5 
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