Early surge in tick bites prompts warnings in the Netherlands

Tick bites across the Netherlands have surged to unusually high levels early in the season, with officials warning the peak has not yet arrived. Data from Tekenradar.nl shows 28 percent of weekly monitors reported tick bites in late May, a level that is typically seen during peak summer months rather than early-season activity.

Unusual spring weather triggers surge in tick bites in the Netherlands

The surge follows what biologist Arnold van Vliet from Wageningen Universiteit describes as a "special combination" of weather events. After an extremely dry spring with some regions receiving only a few millimetres of rain in April, rainfall in mid-May created ideal conditions for ticks.

"The drought in spring was good for us, because in principle it makes ticks less active," Van Vliet told NOS. "But the rainfall in mid-May came at a good moment for the ticks. As a result, they dried out less, which affects how they go hunting."

The rain was followed by extreme heat in late May, coinciding with the Whit holiday weekend. This combination drew people outdoors just as tick activity increased. "With the nice weather, many people went into green spaces, meaning you enter the tick's domain," Van Vliet explained.

Peak tick season expected within weeks as rainfall returns 

Biologist Van Vliet expects the tick bite peak to arrive next week or the week after, noting that June and July are normally the peak months. Current conditions suggest another surge is likely soon.

"It is rainy now, but temperatures seem to rise again sharply, and precipitation chances are decreasing exactly in the peak season," he said. The pattern mirrors last year, when the June peak marked the highest number of tick bite reports in five years, according to the National Institute for Public Health and Environment.

The monitoring system relies on weekly reports from several hundred participants across the Netherlands who indicate whether they experienced tick bites. The percentage of people reporting bites jumped from 16 percent to 28 percent within a single week around the Whit holiday.

Health experts now urge immediate removal of ticks

Public health guidance has shifted regarding tick removal timing. Van Vliet noted that previous advice focused on removal within 24 hours, but current guidance emphasises immediate action.

"Now we know: the faster you remove it, the lower the chance of contracting Lyme disease," he said. An estimated 1,5 million people receive tick bites annually in the Netherlands, with approximately 27.000 contracting Lyme disease. Between 1.000 and 1.500 people develop long-term complications including joint pain, heart disease and concentration problems.

Beyond Lyme disease, Dutch ticks can transmit tick-borne encephalitis (TBE), a viral infection causing meningitis. While more common in Central and Eastern Europe, TBE infections have increased in the Netherlands in recent years, which researchers partly attribute to climate change.

How climate change & wildlife expand the tick threat

The Scientific Climate Council (WKR) and the Health Council of the Netherlands recently advised the government that climate change broadly favours tick expansion. Warmer winters reduce tick mortality and may extend their active period throughout the year.

Van Vliet emphasised that climate change impacts require continuous monitoring. "The evolving relationship between climate change and tick populations should be closely monitored in the coming years due to potentially serious public health impacts," he said.

Provincial data from 2025 showed Drenthe had the highest tick bite rate at 142 reports per 100.000 inhabitants, followed by Gelderland with 83 and Flevoland with 79. Zuid-Holland recorded the lowest rate at 22 per 100.000 inhabitants.

Van Vliet's key advice remains simple but crucial: "After a visit to green areas, do a tick check."