Varicella Virus Infection Severity

Varicella virus is exclusively a human neurotrophic alphaherpesvirus. Primary infection of the virus causes varicella (chickenpox). The virus becomes latent in the CNS, then years later, in association with an increase in age and decline in cell mediated immunity, varicella reactivates and herpes zoster, also referred to as shingles, develops. In people primary infection as adults usually results in a more severe disease and can be followed by interstitial pneumonia. In younger patients with HIV infection, herpes zoster (VZV) may be one of the first indicators of the disease. In general apes usually develop localized infection from varicella inoculation. Naturally acquired antibodies to VZV or to a virus that cross reacts with VZV, has been reported to occur in most chimps raised in the wild. Chimpanzees in captivity have developed vesicular lesions typical of chicken pox. The virus was identified by EM however; VZV specific antibodies or nucleic acid was not isolated. In one report vesicular lesions that contain zoster were observed in gorillas. Subcutaneous inoculation of two chimpanzees with VZV resulted in a mild localized infection and the disease did not disseminate like human chicken pox. This reaction is similar to what is seen in approximately 4% of the children vaccinated for varicella.

Shingles has never been reported in animals infected with VZV.