Tick-Borne Encephalitis is a viral infectious disease of the central nervous system (brain, meninges, and/or spinal cord), caused by a virus from the genus Flavivirus (family Flaviviridae).
How does infection occur?
most often by the bite of an infected tick,
less often after consuming unpasteurized dairy products from infected animals (so-called alimentary route).
Source of pathogen (reservoir)
the virus circulates mainly among small mammals (e.g., rodents) and other animals (wild and domestic), and humans are "accidental" hosts.
Incubation period
usually about 7–14 days, possibly up to 28 days,
after alimentary route infection, it can be shorter (about 4 days).
Who is most at risk?
people living or staying in green/wooded areas and performing outdoor activities (e.g., walking, running, cycling, mushroom picking, gardening, forestry/agriculture work).
2. Symptoms of Tick-Borne Encephalitis
In some people, the infection may be asymptomatic. If symptoms appear, TBE often has 2 phases: first "flu-like" symptoms, and then (in some patients) neurological symptoms.
Most common symptoms (phase 1):
fever,
headache, muscle pain,
fatigue, "malaise",
nausea.
More severe symptoms (phase 2 – nervous system involvement):
severe headache, high fever,
stiff neck,
disturbances of consciousness, confusion,
balance/coordination problems,
paresis, convulsions.
Possible complications
in some patients, long-term neurological symptoms may persist (e.g., weakness, paresis, chronic headaches, concentration problems).
mortality in the European subtype is low but real (of the order of 0.5–2% in clinical cases).
When to urgently see a doctor/ER?
high fever + severe headache,
stiff neck,
disturbances of consciousness, convulsions,
new paresis or paralysis,
persistent vomiting, rapid deterioration of general condition.
3. Where does Tick-Borne Encephalitis occur?
This is a disease found mainly in Europe and parts of Asia. In Europe, it concerns especially central, eastern, and northern areas, and in Asia, among others, regions of Russia and selected areas of China and Japan (depending on the virus subtype).
In Poland
cases occur in various regions, but the highest risk concerns north-eastern Poland; the tick activity season most often covers the period from spring to autumn.
This information is particularly important for people planning:
recreation "in nature" (forest, lakes, meadows, camping),
trips to endemic areas in Europe/Asia,
work or regular hobby outdoors.
4. How to protect yourself against Tick-Borne Encephalitis?
A. General prevention (without vaccination)
use tick repellents,
wear protective clothing: long sleeves and trousers, preferably light-colored (easier to notice a tick),
after returning from green areas: examine the whole body (especially groin, armpits, behind knees, around ears and hairline) and remove ticks with tweezers,
in risk areas, avoid unpasteurized milk and its products.
B. Vaccination against TBE
This is the most effective method of preventing TBE (vaccines are inactivated).
What vaccines? (examples available in Poland)
FSME-IMMUN 0.5 ml – for people ≥16 years; FSME-IMMUN Junior for children 1–15 years.
Encepur Adults – for adolescents from 12 years and adults; Encepur K – for children over 1 year of age.
For whom recommended?
people living or frequently staying in endemic areas,
people active outdoors (recreationally or professionally),
travelers planning trips to regions with increased risk.
Vaccination schedule (most commonly used)
3 doses in the primary cycle: 0 → 1–3 months → 5–12 months.
accelerated schedules are also available (e.g., when you want to get protection faster before the season) – the choice depends on the preparation and clinical situation.
Booster doses and protection time
after completing the primary cycle: first booster dose after 3 years,
then usually every 5 years until age 60, and after age 60 every 3 years (details may depend on age and preparation).
Additional notes
protection usually develops after the 2nd dose, and fuller and long-lasting is obtained after 3 doses.
5. Summary
TBE is a dangerous viral disease that can lead to meningitis and encephalitis and long-term neurological complications, and treatment is mainly symptomatic. Vaccination is particularly worth considering if you often stay in forests/meadows, live in a region with higher risk, or plan a trip to endemic areas. It is best to start vaccination in advance (optimally before the tick season), because the primary cycle takes time, and protection builds up gradually.