A 12-year-old girl presents with a 3-day history of a body-wide pruritic vesicular rash (Figure 108-1). The episode started 24 hours before the rash with fever and malaise. The patient is diagnosed with varicella and no antiviral medications are given. Acetaminophen or ibuprofen are recommended for fever and comfort, avoiding aspirin to prevent Reyes syndrome.
Chickenpox in a child. Note lesions in various stages (papules, intact vesicles, pustules, and crusted papules) caused by multiple crops of lesions. The vesicles are on a red base. (Used with permission from Richard P. Usatine, MD.)
Varicella (chickenpox) is a highly contagious viral infection that can become reactivated in the form of zoster.
Varicella-zoster virus (VZV) is distributed worldwide.
The rate of secondary household attack is more than 90 percent in susceptible individuals (Figure 108-2).1
Adults and immunocompromised patients generally develop more severe disease than normal children.
Traditionally, primary infection with VZV occurs during childhood (Figure 108-3). In childhood, it is usually a benign, self-limited illness in immunocompetent hosts. It occurs throughout the year in temperate regions, but the incidence peaks in the late spring and summer months.
Neonatal varicella is a serious illness with a mortality rate up to 30 percent.2 The risk of infection and the case fatality rate are significantly increased if a mother has symptoms less than five days prior to delivery. The time to delivery allows insufficient time for the development of maternal IgG and passive transfer of protection to the fetus.3 Postnatally acquired varicella that occurs beyond 10 days after birth usually is mild.4
Prior to the introduction of the varicella vaccine in 1995, the yearly incidence of chickenpox in the US was approximately 4 million cases with approximately 11,000 hospital admissions and 100 deaths.5
As the vaccination rates steadily increased in the US, there has been a corresponding fourfold decrease in the number of cases of chickenpox cases down to disease rates of from 0.3 to 1.0 per 1000 population in 2001.5
Chickenpox in sisters seen before the varicella vaccine was available. The girls are feeling better now that the disease is resolving. (Used with permission from Richard P. Usatine, MD.)
Chickenpox in a child. Note the widespread distribution of the lesions. The honey-crusted lesion on the eyebrow suggests a secondary bacterial infection (impetigo) has developed. (Used with permission from Richard P. Usatine, MD.)
Etiology and Pathophysiology