Varicella, commonly known as chickenpox, is a common, acute, and highly contagious infection caused by the herpesvirus varicella-zoster, the same virus that, in its latent stage, causes herpes zoster (shingles).
Chickenpox can occur at any age, but it's most common in children ages 2 to 8. Congenital varicella may affect infants whose mothers had acute infections in their first or early second trimester. Neonatal infection is rare, probably because of transient maternal immunity. However, neonates born to mothers who develop varicella 5 days before delivery or up to 2 days after delivery are at risk for developing severe generalized varicella. Second attacks are also rare. This infection is transmitted by direct contact (primarily with respiratory secretions; less commonly, with skin lesions) and indirect contact (airborne). The incubation period usually lasts 14 to 17 days but can be as short as 10 days and as long as 20 days. (See Incubation and duration of common rash-producing infections, page 232.) Chickenpox is 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).
Chickenpox 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.
Most children recover completely. Potentially fatal complications may affect children on corticosteroids, antimetabolites, or other immunosuppressants and those with leukemia, other neoplasms, or immunodeficiency disorders. Congenital and adult varicella may also have severe effects.
Chickenpox 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. It progress to papules and then clear vesicles on an erythematous base (the so-called dewdrop on a rose petal). These become cloudy and break easily; then scabs form.
The rash spreads to the face and over the trunk of the body, then to the limbs, buccal mucosa, axillae, upper respiratory tract, conjunctivae and, occasionally, the genitalia. New vesicles continue to appear for 3 or 4 days, so the rash contains a combination of red papules, vesicles, and scabs in various stages.
Congenital varicella causes hypoplastic deformity and limb scarring; retarded growth; and central nervous system and eye manifestations. In progressive varicella, an immunocompromised patient may have lesions and a high fever for over 7 days.
Severe pruritus with this rash 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.
Diagnosis rests on the characteristic clinical signs and usually doesn’t require laboratory tests. However, the virus can be isolated from vesicular fluid within the first 3 or 4 days of the rash; Giemsa stain distinguishes varicella-zoster from vaccinia and variola viruses. Serum contains antibodies 7 days after onset.
Chickenpox calls for droplet and contact isolation until all vesicles and most of the scabs are dry (no new lesions; usually 1 week after the onset of the rash). Children with only a few remaining scabs are no longer contagious and can return to school. Congenital chickenpox requires no isolation.
In most cases, treatment consists of local or systemic antipruritics: lukewarm oatmeal baths, calamine lotion, or diphenhydramine (or another antihistamine). Antibiotics are unnecessary unless bacterial infection develops. Salicylates are contraindicated because of their link with Reye's syndrome.
Susceptible patients may need special treatment. When given up to 72 hours after exposure to varicella, varicella-zoster immunoglobulin may provide passive immunity. Acyclovir and famciclovir, antiviral agents, may slow vesicle formation, speed skin healing, and control the systemic spread of infection.
Care is supportive and emphasizes patient and family teaching and preventive measures.
❑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.
❑Varicella vaccine, part of the recommended childhood immunization schedule, effectively prevents infection. It's also effective if given 5 days post-exposure.
❑To help prevent chickenpox, don’t admit a child exposed to chickenpox to a unit that contains children who receive immunosuppressants or who have leukemia or immunodeficiency disorders. A vulnerable child who has been exposed to chickenpox should be evaluated for administration of varicella-zoster immunoglobulin to lessen the severity of the disease.
Review other book chapters online related to Smallpox:
Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
|
More About This Book:
Title: Professional Guide to Diseases (Eighth Edition) Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2005 ISBN: 1-58255-370-X 
|
|
What do you think about the features of this website? Take our user survey and have your say:
Next articles:
Tools & Services:
Medical Articles:
Search Specialists by State and City
By using this site you agree to our Terms of Use. Information provided on this site is for informational purposes only; it is not intended as a substitute for advice from your own medical team. The information on this site is not to be used for diagnosing or treating any health concerns you may have - please contact your physician or health care professional for all your medical needs. Please see our Terms of Use.
Copyright © 2009 Health Grades Inc. All rights reserved.
