They have brown and yellow striped legs, are almost like spiders and are introduced by migratory birds: ticks of the genus Hyalomma.

Unlike endemic ticks such as the wood tick (Ixodes ricinus), which often waits weeks or months for a passing host, Hyalomma ticks hunt.

They can recognize their host animals, such as horses or cattle, up to ten meters away with their eyes or chemical senses and then track them for hundreds of meters.

What makes them so dangerous, among other things?

"A tick can absorb up to eight milliliters of blood," says Ute Mackenstedt from the parasitology department at the University of Hohenheim.

"With 200 ticks that can infest a horse, that alone becomes a problem." For the expert, ticks are the most dangerous vectors of all,

even more dangerous than mosquitoes.

"Ticks transmit an incredible number of different pathogens," says Mackenstedt, "including bacteria like rickettsia, which cause tick-borne spotted fever, and viruses, which can lead to deadly diseases like Crimean-Congo hemorrhagic fever."

Peter Philipp Schmitt

Editor in the department "Germany and the World".

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One of the ticks, with its very unusual appearance, was first discovered in December 2015 on a horse near Frankfurt.

Only Lidia Chitimia-Dobler from the Bundeswehr Institute for Microbiology in Munich was able to identify it under the microscope as Hyalomma rufipes, a tick tick that has its traditional distribution area in Africa.

As a result, Ute Mackenstedt and her team in Hohenheim started the "Tropical Ticks" project.

In order to find out how many and also which ticks occur in Germany, she asked the population to send ticks to her institute.

The campaign ended after three years at the end of December.

Exactly 8107 ticks could be examined.

The results of this citizen science study were presented this week at a three-day tick congress at the University of Hohenheim.

Flown in on migratory birds

"Two things surprised us," says Mackenstedt.

"On the one hand, that the alluvial forest ticks are much more widespread in Germany than previously thought, and on the other hand that Hyalomma ticks are the third most common to be found here." A good half of the ticks sent in, 4058, were alluvial forest ticks (Dermacentor reticulatus). , which belong to the colored ticks.

They are endemic, like to walk with dogs, can transmit canine malaria and also the dreaded tick-borne encephalitis (TBE) virus.

"We thought it was mostly found in eastern Germany and Baden-Württemberg, but as our study shows, it can now be found all over Germany, even on Sylt," reports Ute Mackenstedt.

Reasons for the widespread spread could be an increased number of fallow areas, such as meadows that are no longer mowed regularly.

Ticks of the Hyalomma genus, on the other hand, are still being introduced into Germany.

"After hatching, the larvae attach themselves to migratory birds," says Mackenstedt.

"There they suck blood, shed their skin and finally fall off as nymphs here in Germany." Hyalomma rufipes from Africa in particular needs high temperatures and long dry periods, like the ones in 2019 and 2020, in order to be able to survive.

That is why last year, when there was more rain and at the beginning of the year also a cold snap, fewer nymphs and later also adults, i.e. adult males and females, were found.

On the other hand, Hyalomma marginatum, a genus introduced from eastern regions such as the Caucasus, is more cold-resistant.

“But the dry phases are crucial,” says Mackenstedt.

"Only when it's been warm for a long time and doesn't rain

fungi against ticks

Ticks are difficult to get rid of.

"The goal must be that we make ourselves unattractive as landlords," says Mackenstedt.

For example with tablets for dogs or substances with which we can spray our skin.

On the other hand, acaricides should not be used on a large scale: the pesticides or biocides kill not only ticks, but also soil mites, for example, which are important for the ecosystem.

At the parasitology department in Hohenheim, Mackenstedt is also researching new control methods from nature, including entomopathogenic fungi, which, however, are cultivated in the laboratory.

The fungi enter ticks via the airways and overgrow them.

Even that won't get entire areas tick-free, but that's not what the expert is about.

"However, we could try to use such fungi to reduce the number of ticks on a regional basis," says Ute Mackenstedt, "for example in forest kindergartens, on playgrounds or barbecue areas - i.e. where contact between humans and ticks takes place particularly frequently."