Viral Encephalitis



Infectious encephalitis is caused mainly by viral agents, among which the most common is herpes simplex virus (HSV), followed by varicella-zoster virus, enteroviruses, Japanese encephalitis virus, and the recently discovered Zika virus. The introduction of new vaccines and improvement in vaccination rates have led to great decrease in the incidence of encephalitis due to common viruses such as measles, mumps, and poliovirus. Some uncommon viral pathogens, such as human immunodeficiency virus (HIV) and prion (an infectious protein particle similar to a virus but lacking nucleic acid), also cause viral encephalopathy, and these cases need to be differentiated from more common forms in the clinical setting. The clinical features of encephalitides caused by different viruses are similar, and, in addition, the same virus may sometimes present with different clinical features. Clinical diagnosis can therefore be challenging, especially if cerebrospinal fluid (CSF) polymerase chain reaction (PCR) is negative, as is often the case in the early stages of encephalitis. In such situations, imaging studies of the CNS may provide key clues to the diagnosis and even help identify the etiological agent. For example, brain magnetic resonance imaging (MRI) can play a crucial role in suggesting a diagnosis of herpes simplex encephalitis (HSE) and thus facilitate early initiation of antiviral treatment, which can markedly decrease mortality and improve outcomes.


Infectious encephalitis Cerebrospinal fluid Herpes simplex encephalitis EV71 HIV Prion 


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Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  • Yan Ren
    • 1
  1. 1.Department of RadiologyHuashan Hospital, Fudan UniversityShanghaiChina

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