In this country, ticks are now also looking for hosts in winter, so that when you spend time outdoors there is a risk of a tick bite all year round. This is associated with a year-round risk of infection for tick-borne diseases such as Lyme disease or tick-borne encephalitis (TBE).
A research team led by Professor Dr. Christina Strube from the Hannover University of Veterinary Medicine (TiHo) investigated in a current study. The results are published in the specialist magazine “Ticks and Tick-borne Diseases”.
Climate influences tick activity
According to the researchers, climatic conditions are known to have a significant influence on the activity of ticks. The conclusion is that the average temperatures that have been rising for decades and, in particular, the mild winters with little or often no snowfall are increasing tick activity.
Two species of ticks in particular have so far been widespread in Central Europe, the common wood tick (Ixodes ricinus) and the meadow tick (Dermacentor reticulatus), with the latter becoming increasingly common in recent years, the team reports.
It was already known that the spotted tick was also active in the winter months, but the common wood tick was previously only rarely found in the colder months, the researchers continued. They carried out extensive studies to determine how active the ticks actually are in the winter months.
Three different surveys
“We were able to observe the winter activities of these two tick species in three different approaches: in the field, with so-called tick plots and using ticks that veterinarians sent us and which we evaluated,” reports Prof. Dr. Strub.
From April 2020 to April 2022, areas in the open were regularly sampled using the flag method, in which a cotton cloth is pulled over the ground so that active ticks can climb onto the underside of the cloth and then be collected and counted, the researchers explain.
The tick plots used for observation are quasi-natural outdoor habitats in which active ticks can climb up thin wooden sticks so that they can be easily recognized on these sticks. Active ticks were counted three times a week.
In addition, the infestation of pets was recorded as part of a nationwide study from March 2020 to October 2021. Veterinarians sent in almost 20,000 ticks, which primarily affected dogs and cats, so that the researchers could determine their activity in the winter months.
Ticks active all year round
The evaluation of the surveys showed that the meadow tick is constantly active over the winter as long as there is no snow. “It can only be stopped by a solid blanket of snow,” says Strube.
According to the researchers, the common wood tick was also active from December to February in mild winters and a significant increase in the activity of both tick species could be observed, especially in February.
“The mild winters ensure that ticks look for hosts even during the cold season. This means that pets should now be protected from ticks all year round. And of course people should also be careful in winter and check themselves for ticks after spending time outdoors,” summarizes Prof. Strube.
Because ticks can transmit various infectious diseases, there is now a year-round risk of infection for people and animals. Babesiosis and anaplasmosis and, to a lesser extent, Lyme disease are particularly important for animals, and Lyme disease and TBE are particularly important for humans. (fp)