• A disease caused by the mosquito-borne Japanese encephalitis virus (JEV).
  • The virus itself is from the family Flaviviridae.
  • Reservoirs of the virus: Domestic pigs, wild birds (especially herons) and transmission to humans may cause severe symptoms; no person to person transmission.
    • Most important disease vectors: mosquitoes (Culex tritaeniorhynchus, Culex vishnui).
  • Most prevalent in Southeast Asia and East Asia.
  • Other name: Japanese B encephalitis
  • 5 to 15 day incubation period; most infections are asymptomatic.
    • Encephalitis in 1 in 250 infections.
  • In humans, symptoms may include:
    • Severe rigors – marking onset of disease.
    • Fever, headache and malaise – non-specific.
      • May last for 1 and 6 days.
    • During acute encephalitic stage:
      • neck rigidity, cachexia, hemiparesis, convulsions, elevated body temperature between 38–41 °C, mental retardation.
    • In persons with CNS involvement:
      • deafness, emotional lability, hemiparesis.
  • Increased activation of microglia following infection influences disease outcome.
  • In animals, important signs are:
    • infertility and abortion –pigs
    • neurological disease – horses
    • systemic signs:
      • fever, lethargy and anorexia


  • Physician may do/request:
    • History & Physical Exam
    • Laboratory tests:
      • IgM capture ELISA
      • Indirect fluorescent antibody staining



  • Primarily supportive treatment; no specific treatment for the disease.
    • Feeding assistance, breathing or seizure control whenever necessary.
    • Mannitol – for increased intracranial pressure.

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