Japanese Encephalitis

Last updated 30/05/16

Definition

• Encephalitis caused by infection from the Japanese Encephalitis arborvirus transmitted via mosquitos

Features

• Endemic to throught Asia and Russia
• Periodically spreads from PNG to Torres Strait Islands
• Incubation period 6-8 days
• Mortality 5-35% (mean 7%)

Cause

• Japanese Encephalits virus
• Arbovirus of the flaviviridae family
• Natural host wading birds and pigs
• Transmitted by Culex annulirostris mosquito bite
• Possibly also Aedes and Anoepholes species

Associated Signs & Symptoms

• Prodrome 2-3 days
• Fever
• Malaise
• Headache
• Nausea, vomiting
• Encephalitis
• Nuchal ridigity
• Dizziness
• Deteriorating consciousness
• Seizure

Complications

• Prolonged encephalitis
• More common in children <5yrs
• Slow recovery
• Death
• Neurological sequelae

Differential Diagnosis

Investigations

• Serum
• Serology + PCR
• Specific IgM

Management

• Prevention
• Immunisation
• Mosquito control
• Acute Management
• Seizure management
• Airway management as required
• Supportive management

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References