Tick Borne Encephalitis

Related to yellow fever, dengue fever and Japanese encephalitis virus.

Is caused by several species of ticks living in Central and Eastern Europe and parts of Asia. Tick activity starts when soil temperature rises to 5-70C in March or April and ends in Fall.

In Mediterranean countries ticks are more active November-January.

Ticks are worse in wet summers and mild winters.
The risk of infection from specific tick bites ranges from 1:200-1:900.

People at highest risk of being bitten include agriculture/forestry workers, hikers/ outdoorsmen and collectors of berries and mushrooms.

These ticks attach to humans at hair-covered portions of the scalp, ears, arms, knee joints, and hands and feet.

- Incubation 2-28 days
- Biphasic symptom

1st Stage (viraemia): fever, headache, myalgia and leuko and thrombocytopenia for 1-8 days. Latency stage then occurs lasting 1-33 days before the

2nd stage. - 2nd Stage Up to 25% of cases develops meningitis, meningo-encephalitis, and transmyelitits. Case fatality rate of 1-5%. Paresis in acute stage- (3-23%) usually involves shoulder or hemiparesis and may sometimes involve cranial nerve pulses.

- Mild disease (55%) meningeal/encephalitis.
- Moderate (37%) moderate meningeal symptoms.
- Severe (8%) severe encephalitis.

- 1gM Elisa on serum (acute)
- Confirmation requires acute and convalescent serum to check for immunity check serology.

TREATMENT: Gammaglobulin and Corticosteroids do not appear to work well. Strict bed rest and observations recommended

- Prolonged hospital stay.
- 50 days- 40% still on sick leave.
- 40% of patients had chronic residual symptoms.

Include neuropsychiatric symptoms (memory loss, stress intolerance, decreased concentration), balance, dysphagia, hearing, headache, and paresis. Negative prognostic factors include middle to high age and the severity of the acute phase.

1) Full recovery in 3 months.
2) Prolonged clinical return with neuropsychiatric and neurological problems.
3) Residual paresis.

In epidemic areas, TBE is one of the most important causes of viral CNS infections. Case fatality and severe effects still is very low (0.5-5%).

1) Common in Austria/Germa ny/Balkan. Invented in 1971 by Dr Kunz.
2) Indicated for long-term residents.
3) Short-term travelers? May consider if significant exposure.
4) Recommended for endemic areas in the Alps
5) People receive 90%protection after the 2nd dose.
6) Vaccine not available in North America but can be specially ordered


1. Consider epidemology of travelers and the disease. Austria has 84% of the population vaccinated. Goal is to have no more than 5-10 hospitalizations per year. Vaccination occurs in schools. Travelers to Austria, Western Europe should consider vaccination if they plan to be outside even including stays in urban parks.

2. Schedule: Day 0 1st, day 14-90 2nd, and 10-12 mos 3rd .5ml for adults and .25ml for children <12 yrs. Boost every 3 yrs.

3. Alternative for travelers arriving into Central /Western Europe. If a person is at a very high risk at exposure the TBE vaccine is available upon arrival at many European clinics.

Compiled June 2001
1. 8th ISTM meeting in Austria
2. Lecture by Dr. Kunz
3. Baxter monograph on TBE.

Tick Borne Encephalitis links

Patient.uk http://www.patient.co.uk/showdoc/27000510/

Travelhealth,co.uk http://www.travelhealth.co.uk/diseases/tick_encephalitis.htm