In 2021, the number of Lyme disease diagnoses with a red ring or rash– known as an erythema migrans, or EM – remained as high as in the previous survey in 2017. GPs diagnosed 25,600 patients with a red ring or rash caused by the Lyme bacteria. For the first time since the first survey in 1994, this number had not increased.

Many diagnoses in north-east Netherlands

Since 1994, RIVM has conducted a survey among GPs every four to five years to track the number of Lyme disease diagnoses. With each survey, this number increased. In the last survey, in 2021, this trend changed and the number of diagnoses with a red rash or ring remained the same. The highest number of diagnoses (per 100,000 inhabitants) was found in municipalities in the north and east of the Netherlands, particularly in the provinces of Drenthe and Groningen. It remains important to check for tick bites in other parts of the Netherlands as well. Every year, about 1.5 million ticks bite someone in the Netherlands. This leads to Lyme disease symptoms in about two to three out of 100 people with a tick bite.

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The number of Lyme disease diagnoses with a red rash or ring in 1994, 2017 and 2021. Visit for more information by municipality.

Decrease in number of GP visits

The number of GP consultations for tick bites in 2021 was much lower than in the previous survey. This may be due to the general decline in GP visits during the COVID-19 pandemic. The stabilisation of the number of Lyme disease diagnoses with a red rash or ring could also be related to the COVID-19 pandemic, for instance because people with an EM were less likely to visit their GP. However, this has not been investigated.

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Lyme disease can often be recognised by an expanding red rash or ring that may appear at the site of the tick bite a few days to weeks after the bite has occurred.

Late peak in tick bite reports on this year

The number of tick bite reports on has risen sharply in recent weeks. After an early start to the tick season, the peak of the season has come late this year. Many more tick bites are expected in the weeks ahead, making it even more important to check for ticks if you have been out in the woods, dunes, park or garden.