Japanese Encephalitis (JE) is a serious viral brain infection caused by the Japanese encephalitis virus (JEV), a mosquito-borne flavivirus related to dengue, yellow fever, and West Nile viruses.
Here’s an overview:
🦠 Cause
Caused by Japanese encephalitis virus (JEV).
Transmitted by the bite of infected Culex mosquitoes, primarily Culex tritaeniorhynchus.
The virus circulates between mosquitoes, pigs, and wading birds — humans are accidental, dead-end hosts (cannot spread the virus to others).
🌏 Geographic Distribution
Endemic in Asia and parts of the western Pacific.
High-risk areas: rural/agricultural regions (especially rice paddies and pig farms).
Countries include India, Nepal, China, Japan, Korea, Southeast Asia, and parts of northern Australia.
⚠️ Incubation Period
Typically 5–15 days after the infective mosquito bite.
🤒 Symptoms
Most infections are asymptomatic or mild, but severe cases can occur.
Mild illness (most common):
Fever, headache, malaise.
Severe encephalitic illness (~1 in 250 infections):
High fever
Neck stiffness
Disorientation/confusion
Seizures
Paralysis
Coma
Case fatality: 20–30%.
Long-term neurological or psychiatric complications: seen in up to 50% of survivors.
🧠 Diagnosis
Based on clinical symptoms and history of travel/exposure in endemic areas.
Confirmed by detecting JEV-specific IgM antibodies in cerebrospinal fluid (CSF) or serum (ELISA test).
💊 Treatment
No specific antiviral therapy.
Supportive care only, including:
Maintaining airway and breathing
Controlling seizures
Managing brain swelling (intracranial pressure)
Hydration and nutrition
🛡️ Prevention
Vaccination (most important):
Safe and effective vaccines are available:
Inactivated Vero cell vaccine – 2 doses, 28 days apart.
Live-attenuated SA 14-14-2 vaccine – used widely in Asia.
Recommended for:
Travelers staying ≥1 month in endemic areas
Residents in endemic regions
Mosquito control & personal protection:
Use insect repellent (DEET, picaridin).
Wear long sleeves and pants.
Sleep under insecticide-treated nets.
Eliminate mosquito breeding sites (stagnant water).
