Japanese encephalitis is a virus spread by the bite of infected mosquitoes. It's more common in rural and agricultural areas. Most cases are mild. Rarely, it causes serious brain swelling with a sudden headache, high fever and disorientation. Treatment involves supportive care. A vaccine is available.

1. JAPANESE ENCEPHALITIS

2. Etiology
• Japanese encephalitis is a zoonotic disease endemic to many states of india
• Etiological agent : ARBOVIRUS
• Vector : culicine mosquito – CULEX TRITAENIORHYNCUS
• Host – birds or pigs (maintained in bird-mosquito- bird or pig-mosquito-pig cycles )
• Infection is acquired when infected culex bites man
• There is no person to person transmission
• ∼ 68,000 cases occur every year
• Typically affects individuals < 15 years old
• Common in areas with irrigated rice fields

4. Clinical features
• Incubation period – 6 to 8 days
• PRODROMAL PHASE ( 1 to 5 days) – following incubation there is prodrome of
fever , headache, nausea , vomiting , myalgia
• ENCEPHALITIC SYMPTOMS – irritability , altered sensorium, convulsions , coma
• Other neurological defects – difficulty in speech , ocular palsies , hemiplegia ,
quadriplegia
• Extrapyramidal features- rigidity, dystonia, coarse tremors, choreoathetosis

5. Diagnosis
• Blood examination – leukocytosis and neutrophilia
• CSF- raised pressure, cell count( initially neutrophilia ..later
PLEOCYTOSIS with lymphocytosis ) , proteins (50% of cases )
• Serology – Antibodies to virus detected by viral neutralization test ,
HIA ,CFT , IGM capture ELISA
• Viral antigens can be detected in csf by indirect immunofluorescence
assay
• RT-PCR
• EEG ABNORMALITIES
• MRI

6. Prevention and treatment
• Treatment – symptomatic , control fever , raised ICT, and convulsions
• Prevention –
a) VACCINATION: JE vaccine
• Travelers spending > 1 month in endemic areas
• Travelers spending < 1 month in endemic areas during periods of JEV
transmission
• Children < 15 years who live in areas with high JEV transmission
• Administration
• 2 doses, 28 days apart
• Given at least one week before exposure
• Booster if last dose ≥ 1 year ago
B) MOSQUITO CONTROL :
• Wear light-colored clothing
• Use insect repellants
• Remove open water containers to minimize mosquito breeding