A retrospective review of autopsies with encephalitis from 1998-2018 in Manitoba, Canada
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Date
2019-12-17
Authors
Tillman, Melanie
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Abstract
Encephalitis morbidity and mortality has been a focus of public and clinical interest, especially with arboviral trends such as West Nile Virus. Worldwide, the majority of encephalitis cases have an unknown etiology. This presents a challenge for diagnosing and treating encephalitis in order to minimize long term neurological deficits or death. A literature review demonstrates a lack of information on common viral etiologies at autopsy, as well as techniques to accurately identify the viral pathogen. In this study, we defined encephalitis as lymphocytic infiltration beyond the glia limitans into brain tissue with associated microglial activation, as demonstrated by immunohistochemistry. We retrospectively reviewed the Manitoba autopsy records from 1998 to 2018 and identified 114 cases of definite or presumed viral encephalitis. Cases with encephalitis at autopsy ranged from stillborn infants to 86 years of age. Males were more affected than females. In 20 cases, a viral entity was identified. The most common proven entities were herpes simplex and polyoma virus followed by West Nile virus. Possible viral encephalitis without definitive cause likely contributed to death in 36 cases. Possible mild viral encephalitis, incidentally, identified at autopsy, was identified in 58 cases with an unrelated cause of death. In most of the severe cases a viral entity was presumed but not identified due to lack of testing or failure of testing methods. There were peaks in August and September of known WNV encephalitis. This suggests an arboviral etiology for cases of possible viral encephalitis contributing to death and incidental mild encephalitis. Developments in PCR technologies may allow increased detection and identification of viruses in cases of encephalitis which present to autopsy without a definite diagnosis, or sometimes even without clinical suspicion of encephalitis.
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Keywords
Autopsy, Encephalitis, Brain