A 12-year-old girl presents with a 3-day history of a body-wide pruritic vesicular rash (Figure 123-1). 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.
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. (Courtesy of Richard P. Usatine, MD.)
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% in susceptible individuals (Figure 123-2).1
- Adults and immunocompromised patients generally develop more severe disease than normal children.
- Traditionally, primary infection with VZV occurred during childhood (Figure 123-3). 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.
- Prior to the introduction of the varicella vaccine in 1995, the yearly incidence of chickenpox in the United States was approximately 4 million cases with approximately 11,000 hospital admissions and 100 deaths.2
- As the vaccination rates steadily increased in the United States, there has been a corresponding 4-fold decrease in the number of cases of chickenpox cases down to disease rates of from 0.3 to 1.0 per 1000 population in 2001.2
Chickenpox in sisters seen before the varicella vaccine was available. The girls are feeling better now that the disease is resolving. (Courtesy of 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). (Courtesy of Richard P. Usatine, MD.)
- Chickenpox is caused by a primary infection with the VZV, which is a double-stranded, linear DNA herpesvirus.
- Transmission occurs via contact with aerosolized droplets from nasopharyngeal secretions or by direct cutaneous contact with vesicle fluid from skin lesions.
- The incubation period for VZV is approximately 15 days, during which the virus undergoes replication in regional lymph nodes, followed by two viremic phases, the second of which persists through the development of skin lesions generally by day 14.3
- The vesicular rash appears in crops for several days. The lesions start as vesicle on a red base, which is classically described as a dewdrop on a rose petal (Figure 123-4). The lesions gradually develop a pustular component (Figure 123-5...