Although the disease is very rare in Denmark, there are usually a handful of cases each year. The forested area around Tisvilde Hegn and elsewhere in northern Zealand are particular risk zones along with parts of Bornholm.

“Infection is usually linked to spending time in risk areas, and typically going off the paths, Peter H.S. Andersen, doctor and head of department at SSI, said in a statement.

“But there have also been cases of TBE where the patient has not demonstrated known risk behaviour by going into in woods or thickets,” he added.

READ ALSO: What you need to know about ticks in Denmark and how to avoid them

Earlier this year, it was reported that people in Copenhagen and surrounding areas of Zealand have increasingly sought vaccination against tick-borne encephalitis (TBE) after an increase in ticks in parts of the countryside.

The risk of TBE remains small but case numbers have increased slightly in recent years. Some 11 cases were registered in 2023 compared with around 1 or 2 annually a decade ago.

Ticks (skovflåter) can be found all over Denmark in forests, meadows, and long grass. They are particularly active during the summer months and increase in number if the weather has been warm and humid.

In Denmark, the most common disease ticks transmit is Lyme disease, but ticks can also carry the very rare but dangerous TBE.

Only people who spend extended time in forests near Tisvilde Hegn as well as on the island of Bornholm should consider vaccination, SSI experts have previously said.

TBE is a viral brain infection caused by a particular tick bite. Flu-like symptoms can occur a week or more after the bite and can develop to include nausea, dizziness, and in around a third of cases, severe long-term problems or permanent neurological damage.

Denmark’s tick season last from spring until autumn.

In contrast to Lyme disease, the TBE virus infects its target quickly after the tick bite.

“That’s why it’s important to remove a tick as soon as you find it. Either with your fingers, a tweezer or a special tick remover,” Andersen said.