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Japanese encephalitis
From WikEM
Contents
Background
- 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
- SAH
- Lyme disease
- Brain abscess
- Bacterial endocarditis
- Toxic / metabolic encephalopathy
Altered mental status and fever
- Infectious
- Sepsis
- Meningitis
- Encephalitis
- Cerebral malaria
- Other
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
