TBE diagnosis can only be verified by means of laboratory techniques. Definitive diagnosis of tick-borne encephalitis is based on

• isolation of the virus from blood or cerebrospinal fluid or from post mortem tissues;
• serological tests of paired sera;
• demonstration of specific IgM in acute serum.

Polymerase chain reaction (PCR) can also be used to amplify viral DNA or RNA from blood or liquor samples.