Varicella and Herpes Zoster at a Glance
- Varicella (chickenpox) and herpes zoster (shingles) are distinct clinical entities caused by a single member of the herpesvirus family, varicella-zoster virus (VZV).
- Varicella, an acute, highly contagious exanthem that occurs most often in childhood, is the result of primary VZV infection of a susceptible individual.
- The rash usually begins on the face and scalp and spreads rapidly to the trunk, with relative sparing of the extremities. Lesions are scattered rather than clustered, and progress from rose-colored macules to papules, vesicles, pustules, and crusts. In varicella, in contrast to smallpox, lesions in all stages are usually present on the body at the same time.
- In normal children, systemic symptoms are usually mild and serious complications are rare. In adults and immunologically compromised persons of any age, varicella is more likely to be associated with life-threatening complications.
- Where use of varicella vaccine in susceptible children and adults is widespread, the incidence of varicella is markedly reduced, although breakthrough varicella may occur.
- Herpes zoster is characterized by unilateral, dermatomal pain, and rash that results from reactivation and multiplication of endogenous VZV that had persisted in latent form within sensory ganglia following an earlier attack of varicella.
- The erythematous, maculopapular, and vesicular lesions of herpes zoster are clustered rather than scattered because virus reaches the skin via sensory nerves rather than viremia.
- Herpes zoster is most common in older adults and immunosuppressed individuals.
- Pain is an important clinical manifestation of herpes zoster, and the most common debilitating complication is chronic pain or postherpetic neuralgia (PHN).
- Antiviral therapy and analgesics reduce acute pain; lidocaine patch (5%), high dose capsaicin patch, gabapentin, pregabalin, opioids, and tricyclic antidepressants may reduce the pain of PHN.
- A live attenuated zoster vaccine reduces the incidence of herpes zoster by one-half and the incidence of PHN by two-thirds.
Epidemiology of Varicella
Varicella is distributed worldwide, but its age-specific incidence differs in temperate versus tropical climates, and in populations that have received varicella vaccine. In temperate climates in the absence of varicella vaccination, varicella is endemic, with a regularly recurring seasonal prevalence in winter and spring, and periodic epidemics that depend upon the accumulation of susceptible persons. In Europe and North America in the prevaccination era, 90% of cases occurred in children younger than 10 years of age and fewer than 5% in individuals older than the age of 15.1 From 1988 to 1995, there were approximately 11,000 hospitalizations and 100 deaths caused by varicella each year in the United States.2–4 The risk of hospitalization and death was much higher in infants and adults than in children, and most varicella-related deaths occurred in previously healthy people.5 In tropical and semitropical countries, the mean age of varicella is higher and susceptibility among adults to primary VZV infection is significantly greater than in temperate climates. High levels of susceptibility to varicella among adult immigrants from tropical climates are well ...