Up to and including September 14 this year, 448 cases of TBE had been reported, according to recent statistics from the Public Health Agency of Sweden. The number has never been so high during the corresponding period in any other year. The year 2023 comes closest, with 392 cases during the period.
Most people who get TBE do not become seriously ill, but TBE can be severe. Of those who are infected, 10-30 percent will experience flu-like symptoms for 4-7 days. Of these, 20-30 percent are at risk of a second phase, when the virus spreads to the brain or meninges. Some people develop severe symptoms immediately, without an initial phase of fever.
Difficult to explain
What this year's increase in the number of cases is due to is difficult to pinpoint, according to Caroline Schönning, an investigator at the Swedish Public Health Agency.
There are so many factors that affect the TBE situation. It is the tick population, which in turn depends on populations of host animals such as deer and small rodents. Both parts can depend on what the weather has been like during the winter and summer. And in the long term, a warmer climate can lead to longer tick periods.
The number of cases can vary greatly from one year to another, but over the past ten years, cases have increased by about 6 percent per year.
Had an effect?
This spring, the Swedish Public Health Agency issued new recommendations on TBE vaccination. The advice is that all adults and children over the age of three in large parts of southern Sweden - where ticks are most common - should get vaccinated. The question is whether the recommendation has had any effect.
We have not yet been able to evaluate whether the recommendations have resulted in more people getting vaccinated. But you also need to take a number of vaccination doses, so from a medical point of view it also takes a while before the recommendations have an effect, says Caroline Schönning.
She points out that tick season is not over. In 2023, many cases were reported relatively late into the fall. Therefore, there is no reason to wait until next year to get vaccinated.
If you are traveling in areas where ticks and TBE are common, it is a good idea to get vaccinated now as well. Partly because you need a number of doses, and partly because the ticks will be active for quite some time.
Corrected: In a previous version, the correct figures for how many people are at risk of serious symptoms from TBE were not provided.
Year Fall total Fall until 14 September
2026 448
2025 503 336
2024 384 284
2023 595 392
2022 465 304
2021 534 305
2020 274 172
2019 358 255
2018 385,224
2017 391,240
2016 238,163
Source: Public Health Agency of Sweden
