Viral Encephalitides

  • Heng Thay Chong
  • Chong Tin Tan


Viral encephalitis is defined as an inflammation of the brain parenchyma caused by a viral infection. There is often concomitant involvement of the surrounding meninges, a condition generally referred to as meningoencephalitis. This chapter focuses on viral encephalitis as viral meningitis is dealt with in Chap.  14. Other non-infective causes include autoimmune encephalitis and Rasmussen syndrome. The pathological findings in most encephalitides are non-specific and include neuronal death, perivascular cuffing, mononuclear cell infiltration and, later, gliosis. In herpes encephalitis, homogeneous, eosinophilic intranuclear inclusion bodies (Cowdry type A) are seen in about half of the patients in the first week of infection. After about 2 weeks, gliosis, glial nodule and satellitosis–neuronophagia with necrosis and haemorrhage are seen. In rabies infection, intracytoplasmic inclusion or Negri bodies are seen in 80% of patients. In less common infections, the pathological process may differ. In acute Venezuelan equine, Eastern equine and Nipah and Hendra encephalitides, there is widespread vasculitis, thrombosis and infarction, while demyelinating encephalitis is seen in herpes simplex encephalitis in the immunocompromised and in human herpesvirus 6 (HHV6) infections [1–5].


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Copyright information

© The Author(s) 2019

Authors and Affiliations

  • Heng Thay Chong
    • 1
  • Chong Tin Tan
    • 2
  1. 1.Western HealthMelbourneAustralia
  2. 2.University of MalayaKuala LumpurMalaysia

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