Japanese Encephalitis can be strongly suspected in the presence of the following features
- Disease Transmission – Months of September to December.
- Age group – Children between 2–15 years.
- Residence – Rural & peri urban.
- Epidemiological evidence – Similar cases reported in the area in the current year or previous year.
- High fever of short duration (<3 days).
- Change in the level of consciousness.
- Significant difference between right and left side of body because of paralysis (i.e. lack of movements on one side/abnormal movements/abnormal postures).
- Acute onset of illness with high grade fever, headache, vomittings.
- A variable prodromal period followed by involvement of central nervous system with drowsiness and convulsions. Loss of consciousness for > 24 hours with variable neurological signs.
- Confirmation by viral serology.
1. Suspected case: Acute onset of fever altered sensorium in pediatric age group less than 15 years of age.
2. Probable case: Acute onset of fever with altered sensorium with or without convulsions, increased intracranial pressure, without neck stiffness. rigidity and absence of other probable cause of encephalitis in paediatric age group (below 15 years.)
3. Confirmed case: Laboratory evidence of one or more of the following
- Presence of viral RNA by PCR.
- Presence of 1 gM antibodies.
- Isolation of virus.
- Serum samples.
- Blood clot after serum separation.
- Cerebro spinal fluid.
- Convalescent serum sample.
- Brain biopsy/Necropsy.
- Autopsy material whole brain or brain tissue.