Swedish health agency reports record high tick-borne encephalitis cases this September

According to the Public Health Agency of Sweden, 448 cases of tick-borne encephalitis have been reported through 14 September, setting a new record for the period. This exceeds the previous high of 392 cases recorded during the same span in 2023. TBE can spread to the brain or meninges in a significant portion of those infected, causing serious disease and sometimes death.

Caroline Schönning, an investigator at the agency, says the rise is difficult to attribute to a single cause, citing tick numbers, the populations of deer and small rodents, and weather patterns as contributing factors. Over the past decade, case numbers have risen steadily. The agency introduced updated vaccination guidance in the spring, recommending that all adults and children older than three in large parts of southern Sweden receive the TBE vaccine. Officials have not yet been able to assess whether the new guidance has increased vaccination uptake, and they stress that the tick season continues well into autumn, so vaccination should not be postponed.