Diagnosis: Herpes zoster
The patient had a classic case of herpes zoster (HZ), caused by a reactivation of the varicella-zoster virus (VZV), which also causes chickenpox. HZ is characterized by a painful vesicular rash distributed in a dermatomal pattern, as opposed to the chickenpox rash, which is generalized and more likely to be associated with systemic symptoms. Both rashes develop new lesions over time, producing vesicles in a variety of stages and sizes. The vesicles rupture and crust over as the patient recovers.1
Unintended results of immunization. The varicella vaccine—a live attenuated vaccine prepared from the Oka/Merck strain of VZV—may produce symptomatic infections.2 Breakthrough chickenpox with wild-type varicella is also possible after immunization, although such infections are typically mild and uncomplicated.3 To learn more, see “Varicella vaccine: Adverse effects, contraindications”.
HZ occurs infrequently in healthy children after natural infection and after immunization.2 In children with leukemia, who are more likely to develop zoster, the incidence of HZ after immunization is about 3 times lower than after natural infection, according to research data supplied by Florence Synn, MD, of Merck & Co, Inc., on May 7, 2008.
Varicella vaccine: Adverse effects, contraindications
In the late 1900s, chickenpox affected about 3.5 million people annually—mostly children. Each year varicella caused 3837 to 6458 hospitalizations and an average of 96 deaths.7 These complications spurred the development of the vaccine,8 which became commercially available in 1995.5
The varicella vaccine has been shown to decrease the incidence of infection by 83% compared with historical controls, to decrease household attack rate by 81% to 90%, and to provide 96% protection when compared to placebo.3 Questions persist about its long-term effect on the complications of chickenpox.3
The vast majority of reported adverse affects (AEs) have been benign and self-limited. According to a 10-year safety review performed after some 55 million doses of the vaccine had been administered, the more serious AEs included 6 cases of herpes zoster (HZ)-related meningitis, 30 additional neurologic syndromes, and 7 patients with disseminated Oka varicella zoster virus infection. Most of these serious AEs involved immunocompromised patients.5 Of 403 samples tested, only 97 of the AEs were identified as Oka-type virus by polymerase chain reaction testing, including 57 of the 697 reports of HZ. Only 3 confirmed cases of secondary transmission of the Oka virus were reported.5
Varivax is contraindicated in immunocompromised and pregnant patients, and vaccinated individuals should avoid close contact with susceptible high-risk individuals for up to 6 weeks after immunization.3 However, studies in vaccinated patients who later developed leukemia provide some reassurance about inadvertent exposure.
Although the varicella vaccine is generally safe and efficacious, physicians should review the immunization status of all household members and discuss contact precautions with patients and their families before administering any live vaccine.