Varicella zoster (VZV) is a herpesvirus, and, like other herpesviruses, it causes both primary and recurrent infection and remains latent in neurons present in sensory ganglia.
VZV is responsible for two major clinical infections of humans:
chickenpox (varicella) and shingles (herpes zoster [HZ]). Chickenpox is a generalized primary infection that occurs the first time an individual contacts the virus. This is analogous to the acute herpetic gingivostomatitis of herpes simplex virus. After the primary disease is healed, VZV becomes latent in the dorsal root ganglia of spinal nerves or extramedullary ganglia of cranial nerves. A child without prior contact with VZV can develop chickenpox after contact with an individual with HZ.VZV is responsible for two major clinical infections of humans:
In 3 to 5 of every 1,000 individuals, VZV becomes reactivated, causing lesions of localized herpes zoster. The incidence of HZ increases with age or immunosuppression.
Patients who are immunocompromised due to HIV disease, cancer chemotherapy, immunosuppressive drug therapy, or hematologic malignancy have an increased susceptibility to severe and potentially fatal HZ. These HZ infections may be deep-seated and disseminated, causing pneumonia, meningoencephalitis, and hepatitis; however, otherwise normal patients who develop HZ do not have a significant incidence of underlying malignancy.