Researchers have found ticks over 1,000 meters above sea level, including larvae. Then the species is considered established, but there is still very little of it.
Previously, no established ticks have been found in Norway over 580 meters above sea level and further north than the Helgeland coast. It has been expected that, among other things, climate change and changes in flora and fauna could lead to forest ticks and mouse ticks spreading northwards and in height.
In January, researchers at the University of Agder and the University of Southeast Norway published a study after mapping the occurrence of larvae of the two tick species in the mountains in southern Norway over time. This is necessary to know if ticks have actually established themselves in a place, and not just ended up there via a host animal.
– We found the tick at the larval stage, which clearly shows that it has been established, as high as 1,000 meters above sea level. When we find larvae, it means that it is certainly adult ticks that have laid eggs there, and that these have hatched, says co-author and associate professor of biology Lars Korslund to NTB.
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He emphasizes that even if they follow developments closely, it is not the case that people need to change their behavior because of this.
– This information is important, but for public health the picture does not change based on what we have found. The risk of being bitten by a tick at that height is minimal. I would not care about it if I went on a trip there, so to speak, says Korslund.
More important in the future
Changes in the geographical distribution have not been investigated in this study, but such a study is underway.
– We can not say anything with certainty yet. It may be that the tick has been established further north than the Helgeland coast, where it has been documented so far, but it will require a lot of work to establish it. And there will be very little of it in that case, he says.
The investigations in the mountains were done in Lærdal in Vestland county and on Lifjell in Vestfold and Telemark county, and constituted the doctoral degree of lead author Nicolas De Pelsmaeker at the University of Southeast Norway, who defended his dissertation in March. In an interview in forskning.no, he says that climate change and livestock grazing in open country and at altitude will both be affected by and affect the spread of ticks in the future.
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– A higher incidence combined with a longer tick period can lead to increased damage to the livestock industry, says De Pelsmaeker.
Livestock such as tick hosts can also contribute to more ticks in the mountains, and to it being able to spread to even more areas.
Preliminary figures from last year from the Notification System for Infectious Diseases (MSIS) show that the number of registered cases of the tick-borne disease Lyme Lyme disease was one of the few diseases that not only increased in Norway, but also set a new annual record, with 512 cases.
– There was also an apparent increase in the number of detected cases of TBE, tick-borne encephalitis, primarily in Telemark, Agder and Sørlandet. It is an increase that seems to have lasted over three years, but since there are quite a few cases in total in Norway, it is a bit uncertain whether the increase is real, says Randi Eikeland, head of the National Competence Service for tick-borne diseases (Flåttsenteret) at Sørlandet Hospital.
It is also not certain whether the increase is due to an actual increase in tick spread and infectious ticks, an increase in the number of registered cases or that people move more outdoors and are thus more exposed.
Eikeland points out that the increase in tick-borne diseases in 2020 is not so surprising, seen in light of how many Norwegians spent their holidays in Norway and who also went more on walks in the woods and fields.
Before Easter, Eikeland participated in an international seminar where the participating countries compared the development of tick-borne infections during the pandemic.
– Then there was no doubt that the number of TBE cases has increased in countries where there have been strict travel restrictions, such as Norway and the other Scandinavian countries, Austria and Germany, because we have not traveled abroad and are actually more out in nature, she says.
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