Manual for the surveillance of vaccine-preventable diseases. Chapter 17: Varicella
Published Date:Oct 2015
Corporate Authors:National Center for Immunization and Respiratory Diseases (U.S.)
Series:Manual for the surveillance of vaccine-preventable diseases ; chapter 17
Description:Chapter 17 of: Manual for the surveillance of vaccine-preventable diseases. 5th edition, 2011.
Varicella (chickenpox) is a febrile rash illness resulting from primary infection with the varicella-zoster virus (VZV). Humans are the only source of infection for this virus. Varicella is highly infectious, with secondary infection occurring in 61%-100% of susceptible household contacts. Transmission occurs from person to person by direct contact with persons with either varicella or herpes zoster (shingles) lesions or by airborne spread from respiratory secretions or lesions of persons with chickenpox. The incubation period for varicella is 10-21 days, most commonly 14-16 days. Varicella is characterized by a pruritic, maculopapular vesicular rash that evolves into noninfectious dried crusts over a 5- to 6-day period.
Varicella severity and complications are increased among immunocompromised persons, children younger than 1 year of age, and adults. However, healthy children and adults may also develop serious complications and even die from varicella. Severe complications include secondary bacterial infections (most notably those caused by group A beta-hemolytic Streptococcus, e.g., cellulitis, necrotizing fasciitis, septicemia, and toxic shock syndrome), pneumonia, encephalitis, cerebellar ataxia, Reye syndrome, and death.
Congenital varicella syndrome, characterized by hypoplasia of an extremity, skin abnormalities, encephalitis, microcephaly, ocular abnormalities, mental retardation, and low birth weight, may occur among 0.4%-2.0% of infants born to women infected with varicella during the first or second trimester of pregnancy. Infants born to women who develop varicella within the period of 5 days before delivery to 2 days after delivery are at risk of neonatal varicella, which may be severe.
Immunity following varicella infection is considered to be long-lasting and second cases of varicella are thought to be rare. However, second cases may occur more commonly among immunocompetent persons than previously considered.
VZV remains in a latent state in human nerve tissue and reactivates in approximately one in three infected persons during their lifetime, resulting in herpes zoster. Herpes zoster usually presents as a vesicular rash with pain and itching in a dermatomal distribution. Herpes zoster incidence increases with increasing age, especially after age 50, is more common among immunocompromised persons, and among children with a history of intrauterine varicella or varicella occurring within the first year of life; the latter have an increased risk of developing herpes zoster at an earlier age. A decline or a relative absence of cell-mediated immunity is considered to be an important factor in development of herpes zoster in these groups. A zoster vaccine (Zostavax™, Merck & Co., Inc.) is licensed and recommended for adults 60 years of age and older in the United States.
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