Tick-borne encephalitis complex (flavi) viruses

A flavivirus infection of the central nervous system characterised by a biphasic meningoencephalitis.

Transmission is usually by hard ticks of the Ixodes genus. It can also be acquired from consumption of raw (unpasteurised) milk or dairy products.

Disease onset is 4 to 28 days after a bite from an infected tick. Diagnosis is made based on immune status; seasonality; geographical, animal, and arthropod exposures; clinical findings; and radiographic abnormalities.

Treatment consists of supportive care and management of complications. Aciclovir is given empirically until herpes simplex/varicella zoster infection is ruled out.

Most patients recover fully without long-term sequelae.

Vaccines are available in various countries.

Tick-borne encephalitis (TBE) is a flavivirus infection of the central nervous system, characterised by a biphasic meningoencephalitis.[1]Hawker J, Begg N, Reintjes R, et al. Communicable disease control and health protection handbook. 4th ed. Oxford: Wiley Blackwell; 2019 It is transmitted usually by hard ticks of the Ixodes genus.[2]Barlow G, Irving WL, Moss PJ. Infectious diseases and tropical medicine. In: Kumar P, Clark M, eds. Kumar & Clark’s clinical medicine. 9th ed. London: Elsevier; 2016. Disease onset is 4 to 28 days after a bite from an infected tick.[2]Barlow G, Irving WL, Moss PJ. Infectious diseases and tropical medicine. In: Kumar P, Clark M, eds. Kumar & Clark’s clinical medicine. 9th ed. London: Elsevier; 2016. TBE can also be acquired from consumption of raw (unpasteurised) dairy products.[3]Fischer M, Gould CV, Rollin PE. Tickborne encephalitis. In Brunette GW, Nemhauser JB eds. CDC Yellow Book 2020: Health information for international travel. Oxford University Press; 2019 https://wwwnc.cdc.gov/travel/yellowbook/2020/travel-related-infectious-diseases/tickborne-encephalitis