Tick-borne encephalitis (TBE) is a viral infectious disease involving the central nervous system.

[3] The tick-borne encephalitis virus is known to infect a range of hosts including ruminants, birds, rodents, carnivores, horses, and humans.

After an incubation period of approximately one week (range: 4–28 days) from exposure (tick bite) non-specific symptoms occurs.

[4] In ruminants, neurological disease is also present, and animals may refuse to eat, appear lethargic, and also develop respiratory signs.

[4] TBE is caused by tick-borne encephalitis virus, a member of the genus Flavivirus in the family Flaviviridae.

[10] Detection of specific IgM and IgG antibodies in patients' sera combined with typical clinical signs, is the principal method for diagnosis.

[3] It has been stated that lumbar puncture always should be performed when diagnosing TBE and that pleocytosis in cerebrospinal fluid should be added to the diagnostic criteria.

[11] PCR (polymerase chain reaction) method is rarely used, since TBE virus RNA is most often not present in patient sera or cerebrospinal fluid at the time of neurological symptoms.

The risk of infection was noted to be increasing with age, especially in people older than 40 years and it was greater in men than women.

[10] In Sweden, most cases of TBE occur in a band running from Stockholm to the west, especially around lakes and the nearby region of the Baltic sea.