Japanese encephalitis

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Background

Japanese encephalitis geographic distribution
  • Mosquito-borne flavivirus
  • One of the most common causes of encephalitis globally
  • Highly endemic in parts of Asia and the Western Pacific
  • Up to 70,000 cases, 15,000 deaths annually
  • Usually affects children in endemic areas, as most adults have been exposed and are immune
  • Rare in tourists, as the vector Culex mosquito breeds primarily in rural rice paddies

Clinical Features

  • 5-15 day incubation
  • Sudden, high fever
  • Headache
  • Nuchal rigidity and other meningeal signs
  • Seizure (especially in infants)
  • Various pyramidal and extrapyramidal signs

Differential Diagnosis

Altered mental status and fever

Evaluation

  • Usually diagnosed by clinical suspicion
  • Lumbar puncture if any concern for HSV, VZV, or bacterial meningitis
    • Can test CSF for Japanese encephalitis

Management

  • Supportive
    • IVF, electrolyte repletion antipyretics
    • Antiepileptics for seizures
    • Depressed mental status may require intubation for airway protection
  • Consider empiric acyclovir and antibiotics if HSV or bacterial causes not ruled out

Disposition

  • Admit all but very mild illness
  • Recovery can take months, some deficits may be permanent

See Also

External Links

References

Authors

Claire