Spring is on the way in northern Europe. Watch out for ticks.

The first case of tick-borne encephalitis (TBE) has just been reported in Estonia for 2024. According to the report, the number of cases has increased over the last few years.

More than 200 cases were treated in 2023, up from 70 in 2020. The highest incidence was in Parnu County and Saaremaa.

TBE is endemic in the Baltic states of Estonia, Latvia, and Lithuania.

Twenty-four countries in the EU/EEA zone reported 3,734 confirmed cases in 2020.

The notification rate was highest in Lithuania, followed by Slovenia and Czechia. Rates have generally increased across areas of risk, particularly in Slovenia and Austria.

What is tick-borne encephalitis?

Tick-borne encephalitis is a viral disease of the central nervous system. Approximately 70% of cases will have no symptoms.

In symptomatic disease, there are 2 phases of the disease. In the first phase, the individual may experience a high fever, muscle aches and pains, headaches, and general lethargy. The second phase involves the nervous system with signs and symptoms similar to meningitis. There is no specific antiviral treatment. Treatment is largely supportive only.

Subtypes of TBE are recognized. The European subtype appears to be a milder disease to the one seen in far eastern Europe.

How is tick-borne encephalitis transmitted?

TBE is transmitted to humans by ticks. Ticks become active in early spring when the temperatures are consistently above 5-7C. There is a seasonal pattern to TBE with most cases reported between May and November. For 2020, July had the highest number of cases reported.

It can also be transmitted by consumption of unpasteurized dairy products.

Who is at risk of TBE?

In endemic areas, those most at risk include individuals undertaking outdoor activities. These may be recreational or occupational and include camping, fishing and farming. Training exercises in rural areas may also put individuals at risk.

How is TBE prevented?

Prevention mostly lies with personal protection measures. See Insect-borne disease prevention.

Vaccination is also available. WHO advises vaccination for those living in highly endemic areas.

There are currently 4 vaccines available in Europe, (FSME-Immun, Encepur, TBE-Moscow, and Encevir). The first 2 are manufactured in Austria and Germany respectively.

A TBE vaccine is available under the special access scheme in Australia. It is an inactivated viral vaccine.

It is important to assess the true risk of exposure before recommending a course of vaccination.

The schedule is 3 doses. Day 0, 1-3 months, and 5-12 months. Boosters can be given after 5 years. Protection exceeds 90%.

The vaccine is expensive.