Encephalitis Diagnosis

How acute encephalitis diagnosis done?

To confirm the diagnose of AES and to find out the cause for Encephalitis Diagnosis, the National Vector Borne Disease Control Programme (NVBDCP) India, has laid down certain diagnostic criteria. It has also established country wide surveillance programme for AES with a focus on detecting Japanese encephalitis (JE).

This is being done with help of sentinel sites, which is diagnosing JE by lgM Capture ELISA, and virus isolation being done in National Reference Laboratory.

The criteriaare as follows:

• A case is considered as suspected, when a person presents with acute onset of fever with less than 7 days duration along with changes in mental status such as confusion, disorientation, delirium or coma.
With or without

• Development of seizures not associated with any previous condition (excluding febrile seizures).

Such patients fulfilling the clinical criteria of the suspected cases of encephalitis are then classified as following on the basis of laboratory results :

1. Laboratory-Confirmed case for Encephalitis Diagnosis

Suspected case with any one of the following markers:

• Presence of IgM antibody in serum and/ or CSF

• Four times or greater increase in IgG antibody titer in paired sera(acute & Convalescent) through IgM/IgG ELISA, HI, Neutralisation test.

• Antigen detection by immunofluroscence

• Virus isolation from brain tissue

• Nucleic acid detection by PCR

In the sentinel surveillance network Japanese Encephalitis Diagnosis done by Ig M Capture ELISA, and the virus isolation is done in National Reference laboratory.

2. Probable Cases

A case is considered as a probable case of JE when a clinically suspected case is seen occurring in an area and time frame which is close to a laboratory confirmed case of JE in an outbreak.

3. Acute Encephalitis Syndrome due to other agent
Is a clinically suspected case where diagnostic testing is able to identify a cause which is not JE.

4. Acute Encephalitis Syndrome due to unknown agent

Is a clinically suspected case where either of following is applicable:

• The diagnostic tests are not performed

• No etiological agent could be identified on diagnostic tests

• The diagnostic tests results were indeterminate