Questions

Tick-borne encephalitis virus — Questions

Study questions about Tick-borne encephalitis virus — exam-style, clinical-scenario and FAQ.

Mock Exam mode

Sit this set one question at a time. Multiple-choice questions mark themselves; written questions reveal a tickable mark scheme so you can score your own answer. You get a combined score at the end.

14 questions: 12 MCQ, 2 written.

The Far-Eastern subtype has a predilection for the anterior horn cells of the cervical cord, producing a poliomyelitis-like flaccid paralysis of the shoulder girdle and arms.

Retinitis, a purely sensory neuropathy, a hepatic haemorrhagic fever and isolated facial palsy are not the characteristic pattern.

Tick-borne encephalitis is endemic in European forest habitat and acquired from Ixodes tick bites, so extensive forest exposure in the tick season is the indication for its inactivated vaccine. It is a distinct product from the Japanese encephalitis vaccine.

Japanese encephalitis is an Asian rural mosquito-borne disease, and yellow fever does not occur in Europe.

The incubation period is about 7 to 14 days after a tick bite, and tends to be shorter after milk-borne infection.

The other intervals are too short or too long for tick-borne encephalitis.

Tick-borne encephalitis can be acquired by drinking unpasteurised milk or dairy from an infected goat, sheep or cow, which sheds virus during its viraemia.

Sexual, respiratory, rodent-excreta and waterborne routes are not features of the virus.

The European and Siberian subtypes classically run a biphasic course: a grippe-like first phase, a symptom-free remission, then in a minority a neurological second phase. The Far-Eastern subtype is usually monophasic, progressing straight into severe disease.

The course is not confined to laboratory-acquired or milk-borne cases.

Diagnosis rests on serology, chiefly IgM-capture ELISA on serum and cerebrospinal fluid, with a fourfold titre rise in paired sera confirming; serum IgM can persist for several months.

Virus is rarely isolated once neurological disease has begun, and the other options are not diagnostic tests for the virus.

Ixodes ricinus transmits tick-borne encephalitis in Europe and Ixodes persulcatus in Russia and Asia; Ixodes ricinus also transmits Lyme borreliosis, so co-infection can occur.

Hyalomma ticks transmit Crimean-Congo haemorrhagic fever, and the other genera are not the vectors of tick-borne encephalitis.

There is no specific antiviral for tick-borne encephalitis, so management is supportive, with neurological intensive care for severe encephalitis and attention to respiratory function where cervical-cord or bulbar involvement threatens breathing.

Acyclovir treats herpes simplex encephalitis and doxycycline treats the tick-borne bacterium of Lyme disease, neither of which is tick-borne encephalitis virus.

Small rodents are the principal reservoir, sustaining the cycle with Ixodes ticks, including through co-feeding between infected and uninfected ticks on the same host. Large mammals maintain the tick population but rarely transmit the virus.

Pigs, birds and primates are reservoirs for other flaviviruses, not for tick-borne encephalitis.

Effective inactivated whole-virus vaccines based on the European subtype cross-protect against all three subtypes, with efficacy above 95%; they are given as a multi-dose primary series with periodic boosters.

There is no single-dose lifelong tick-borne encephalitis vaccine, and protection is not restricted to the European subtype.

The Far-Eastern subtype is the most severe, with a case-fatality of roughly 20% to 40%, compared with about 6% to 8% for the Siberian and 0.5% to 2% for the European subtype.

Kunjin is a subtype of West Nile virus, not of tick-borne encephalitis virus.

Powassan virus is a member of the tick-borne encephalitis serocomplex, which also contains Kyasanur Forest disease, Omsk haemorrhagic fever and louping ill viruses.

Japanese encephalitis and West Nile viruses form the mosquito-borne Japanese encephalitis serocomplex, and dengue and yellow fever are separate groups.

a. Tick-borne encephalitis in its biphasic form: a grippe-like first phase, a remission, then a neurological second phase of meningitis or meningoencephalitis, typical of the European subtype.

b. The unpasteurised goat’s milk, because tick-borne encephalitis virus can be acquired by the alimentary route from the milk of infected goats, sheep or cattle, an additional exposure to the tick bite.

c. Serology, with IgM-capture ELISA on serum and cerebrospinal fluid and a rising titre in paired sera; virus is rarely isolated once neurological disease has begun.

d. Tick-borne encephalitis vaccination before travel (with tick-bite avoidance and avoiding unpasteurised dairy as supporting measures).

European (Western) subtype: the mildest, with a case-fatality of about 0.5% to 2%; transmitted by Ixodes ricinus.
Siberian subtype: intermediate severity, case-fatality about 6% to 8%, and associated with chronic progressive disease.
Far-Eastern subtype: the most severe, case-fatality about 20% to 40%, often monophasic with prominent paralysis.

MCQ
A characteristic severe manifestation of Far-Eastern tick-borne encephalitis is:
- A. Retinitis
- B. Ascending sensory neuropathy
- C. A haemorrhagic fever with hepatic necrosis
- D. Flaccid paralysis of the shoulder girdle and arms
- E. Isolated facial nerve palsy
Show answer
Correct answer: D
The Far-Eastern subtype has a predilection for the anterior horn cells of the cervical cord, producing a poliomyelitis-like flaccid paralysis of the shoulder girdle and arms.

Retinitis, a purely sensory neuropathy, a hepatic haemorrhagic fever and isolated facial palsy are not the characteristic pattern.
MCQ
A traveller planning summer hiking and camping in the forests of the Baltic states should be offered:
- A. Tick-borne encephalitis vaccine
- B. The Japanese encephalitis travel vaccine
- C. Yellow fever vaccine before departure
- D. No specific arboviral vaccine at all
- E. Rabies pre-exposure vaccine alone
Show answer
Correct answer: A
Tick-borne encephalitis is endemic in European forest habitat and acquired from Ixodes tick bites, so extensive forest exposure in the tick season is the indication for its inactivated vaccine. It is a distinct product from the Japanese encephalitis vaccine.

Japanese encephalitis is an Asian rural mosquito-borne disease, and yellow fever does not occur in Europe.
MCQ
After a tick bite, the usual incubation period of tick-borne encephalitis is:
- A. About 7 to 14 days
- B. A few hours
- C. 1 to 2 days
- D. 6 to 12 weeks
- E. Over 6 months
Show answer
Correct answer: A
The incubation period is about 7 to 14 days after a tick bite, and tends to be shorter after milk-borne infection.

The other intervals are too short or too long for tick-borne encephalitis.
MCQ
Besides a tick bite, tick-borne encephalitis virus is notably acquired by which route?
- A. Sexual contact
- B. Unpasteurised dairy products
- C. Rodent excreta
- D. Respiratory droplets
- E. Contaminated water
Show answer
Correct answer: B
Tick-borne encephalitis can be acquired by drinking unpasteurised milk or dairy from an infected goat, sheep or cow, which sheds virus during its viraemia.

Sexual, respiratory, rodent-excreta and waterborne routes are not features of the virus.
MCQ
The classic biphasic course of tick-borne encephalitis (a febrile illness, a remission, then a neurological phase) is most typical of which subtypes?
- A. The Far-Eastern subtype only
- B. No subtype; the course is monophasic
- C. The European and Siberian subtypes
- D. Only laboratory-acquired cases
- E. Only milk-borne cases
Show answer
Correct answer: C
The European and Siberian subtypes classically run a biphasic course: a grippe-like first phase, a symptom-free remission, then in a minority a neurological second phase. The Far-Eastern subtype is usually monophasic, progressing straight into severe disease.

The course is not confined to laboratory-acquired or milk-borne cases.
MCQ
The mainstay of laboratory diagnosis of tick-borne encephalitis is:
- A. Virus isolation from cerebrospinal fluid
- B. IgM-capture ELISA on serum and cerebrospinal fluid
- C. Blood culture
- D. Tick identification alone
- E. Electroencephalography
Show answer
Correct answer: B
Diagnosis rests on serology, chiefly IgM-capture ELISA on serum and cerebrospinal fluid, with a fourfold titre rise in paired sera confirming; serum IgM can persist for several months.

Virus is rarely isolated once neurological disease has begun, and the other options are not diagnostic tests for the virus.
MCQ
Tick-borne encephalitis virus is transmitted by which ticks?
- A. Ixodes ricinus and Ixodes persulcatus
- B. Amblyomma hebraeum
- C. Rhipicephalus (Boophilus) species
- D. Hyalomma marginatum
- E. Dermacentor andersoni
Show answer
Correct answer: A
Ixodes ricinus transmits tick-borne encephalitis in Europe and Ixodes persulcatus in Russia and Asia; Ixodes ricinus also transmits Lyme borreliosis, so co-infection can occur.

Hyalomma ticks transmit Crimean-Congo haemorrhagic fever, and the other genera are not the vectors of tick-borne encephalitis.
MCQ
What is the treatment for tick-borne encephalitis?
- A. Oral acyclovir
- B. Intravenous ribavirin
- C. Doxycycline
- D. A specific monoclonal antibody
- E. Supportive care, as there is no specific antiviral
Show answer
Correct answer: E
There is no specific antiviral for tick-borne encephalitis, so management is supportive, with neurological intensive care for severe encephalitis and attention to respiratory function where cervical-cord or bulbar involvement threatens breathing.

Acyclovir treats herpes simplex encephalitis and doxycycline treats the tick-borne bacterium of Lyme disease, neither of which is tick-borne encephalitis virus.
MCQ
Which animals are the principal reservoir maintaining tick-borne encephalitis virus in nature?
- A. Pigs
- B. Wild birds
- C. Non-human primates
- D. Small rodents
- E. Cattle
Show answer
Correct answer: D
Small rodents are the principal reservoir, sustaining the cycle with Ixodes ticks, including through co-feeding between infected and uninfected ticks on the same host. Large mammals maintain the tick population but rarely transmit the virus.

Pigs, birds and primates are reservoirs for other flaviviruses, not for tick-borne encephalitis.
MCQ
Which statement about tick-borne encephalitis vaccines is correct?
- A. Only a live-attenuated vaccine exists
- B. There is no effective vaccine
- C. Inactivated European-subtype vaccines cross-protect against all three subtypes
- D. The vaccine protects only against the European subtype
- E. A single dose gives lifelong protection
Show answer
Correct answer: C
Effective inactivated whole-virus vaccines based on the European subtype cross-protect against all three subtypes, with efficacy above 95%; they are given as a multi-dose primary series with periodic boosters.

There is no single-dose lifelong tick-borne encephalitis vaccine, and protection is not restricted to the European subtype.
MCQ
Which subtype of tick-borne encephalitis virus carries the highest case-fatality?
- A. The European (Western) subtype
- B. The Far-Eastern subtype
- C. The Siberian subtype
- D. All subtypes carry an identical case-fatality
- E. The Kunjin subtype
Show answer
Correct answer: B
The Far-Eastern subtype is the most severe, with a case-fatality of roughly 20% to 40%, compared with about 6% to 8% for the Siberian and 0.5% to 2% for the European subtype.

Kunjin is a subtype of West Nile virus, not of tick-borne encephalitis virus.
MCQ
Which virus belongs to the same tick-borne encephalitis serocomplex as tick-borne encephalitis virus?
- A. Japanese encephalitis virus
- B. West Nile virus
- C. Dengue virus
- D. Yellow fever virus
- E. Powassan virus
Show answer
Correct answer: E
Powassan virus is a member of the tick-borne encephalitis serocomplex, which also contains Kyasanur Forest disease, Omsk haemorrhagic fever and louping ill viruses.

Japanese encephalitis and West Nile viruses form the mosquito-borne Japanese encephalitis serocomplex, and dengue and yellow fever are separate groups.
Clinical scenarioA hiker returns from a summer walking holiday in rural Austria. A week after a febrile, flu-like illness that settled, he develops headache, neck stiffness and drowsiness. He recalls a tick bite and had also drunk unpasteurised goat's milk at a farm. a) What is the most likely diagnosis and what is the pattern of illness called? [2] b) Besides the tick bite, what other exposure is relevant and why? [2] c) How would you confirm the diagnosis? [2] d) What single measure could have prevented it? [1]
Model answer
a. Tick-borne encephalitis in its biphasic form: a grippe-like first phase, a remission, then a neurological second phase of meningitis or meningoencephalitis, typical of the European subtype.

b. The unpasteurised goat’s milk, because tick-borne encephalitis virus can be acquired by the alimentary route from the milk of infected goats, sheep or cattle, an additional exposure to the tick bite.

c. Serology, with IgM-capture ELISA on serum and cerebrospinal fluid and a rising titre in paired sera; virus is rarely isolated once neurological disease has begun.

d. Tick-borne encephalitis vaccination before travel (with tick-bite avoidance and avoiding unpasteurised dairy as supporting measures).
SAQName the three subtypes of tick-borne encephalitis virus and rank them by severity. [3]
Model answer
- European (Western) subtype: the mildest, with a case-fatality of about 0.5% to 2%; transmitted by Ixodes ricinus.
- Siberian subtype: intermediate severity, case-fatality about 6% to 8%, and associated with chronic progressive disease.
- Far-Eastern subtype: the most severe, case-fatality about 20% to 40%, often monophasic with prominent paralysis.