Prevalence of Varizella-Zoster Virus Infection among Encephalitis Study Groups World Wide - Abstract
This review has gathered and summarized prevalence data of varicella zoster virus (VZV)
infection among encephalitis patients reported in 20 studies conducted in different areas of the
world. Varicella is considered as a less common disease in tropical areas compared to temperate
areas. According to literature, VZV induced central nervous system (CNS) diseases such as
encephalitis is common among adults compared to children, especially due to vaccination of
children. Studies conducted in California, USA and Australia has concluded that the VZV induced
encephalitis among children has reduced after the introduction of varicella vaccine. However,
it was difficult to perform comparisons between VZV prevalence among encephalitis patients
from tropical and temperate areas and between children and adults. The reasons were, the
limited number of studies found from tropical area, lack of studies conducted exclusively with
adults and the introductions of varicella vaccine since 1995. Different countries have different
legislations regarding varicella immunization. In some countries, it is a part of national vaccination
programmes. Studies included here were not categorized as from pre-vaccination or postvaccination periods of reporting countries. However, among the indicated studies, the highest VZV
prevalence was seen among children suffering with encephalitis in a temperate country (Finland
– 25%) from 1973 to 1987. Lowest was reported in Eastern India (0.38%) from 2011 – 2012, a
region extends across sub-tropical and tropical areas.