Hyalomma ticks from the tropics now also in Germany - with deadly infectious germs on board

Experts are worried: Several finds of tropical ticks in Germany

Experts are worried: Researchers have discovered tropical species of ticks at various locations in Germany. A specimen carried a pathogen of dangerous typhus fever. The scientists fear that the insects could spread here in the future.

Growing danger by ticks

Only a few weeks ago, a growing danger of ticks was warned. The small bloodsuckers can transmit infectious diseases such as Lyme disease and tick-borne encephalitis (TBE). However, researchers in Germany have discovered tick species that are not native to Germany. One of these animals carried a pathogen of dangerous typhus fever. This disease can lead to death if left untreated.

In several places in Germany tropical tick species of the genus Hyalomma were discovered this year. A copy carried a dangerous bacterium. (Image: IMB / Lidia Chitimia-Dobler)

A found specimen contained dangerous bacteria

Tick ​​researchers at the University of Hohenheim in Stuttgart and their colleagues at the Institute for Microbiology of the German Armed Forces (IMB) in Munich this year have detected seven specimens of the tropical species of ticks of the genus Hyalomma.

Although the number sounds manageable, but lets the researchers ring the alarm bells. Experts say the bloodsuckers could establish themselves here, according to a statement.

And another worrying point: a specimen was carrying a dangerous bacterium, Rickettsia aeschlimannii, a known tick-borne typhus.

Illness can be fatal if left untreated

Among other things, typhus fever occurs in higher, colder regions of Central and West Africa, South America and Asia.

After an incubation period of ten to 14 days, symptoms such as headache, chills, high fever and body aches can occur.

After about five to six days, there is a red-blotch rash, from which the name of the disease was derived.

According to health experts, the death rate is untreated up to 40 percent.

Tropical ticks discovered on horses and a sheep

The researchers from Stuttgart and Munich discovered three of the tropical ticks on a single horse, one on a sheep and three others also on three individual horses.

"We've been able to pinpoint five of the seven ticks, four of which are the species Hyalomma marginatum and one of the species Hyalomma rufipes," explains Dr. Lidia Chitimia-Dobler, tick expert at the IMB.

"The remaining two had lost the horse owner in collecting," said the scientist.

"We did not expect hyalomma ticks here in Germany at this time. So far, there were only two single finds in the years 2015 to 2017. "

Found species have not been found in Central and Northern Europe

Hyalomma marginatum and Hyalomma rufipes are native to the dry and semi-arid areas of Africa, Asia and southern Europe. In Central and Northern Europe, they did not occur before.

In the Eurasian area, both species are considered important transmitters of the virus that causes the Crimean-Congo-hemorrhagic fever and the Alkhumra virus, the causative agent of the Arab hemorrhagic fever.

Also, the bacterium Rickettsia aeschlimannii, which triggers a form of tick typhus, can be transmitted by these ticks.

The adult ticks suck blood especially on large animals. The animals can actively move towards their host, covering a distance of up to 100 meters. Man, too, is a potential host of the animals.

In contrast, larvae and nymphs are mainly found in birds and small mammals. They use the same animal for bloodsucking and stay up to 28 days on their host and can be introduced to Germany with migratory birds.

Comparatively large animals

The comparatively large animals with the strikingly striped legs had appeared this year in the Hanover area, in Osnabrück and in the Wetterau, probably introduced by birds.

"These species of ticks could find their way into Germany", fears Prof. Dr. med. Ute Mackenstedt, parasitologist at the University of Hohenheim.

"We will keep an eye on her this year and are preparing to meet her more often in the coming months."

More heat-loving ticks due to global warming

However, this development is not surprising for the expert.

"Due to global warming, we are generally expecting more and more heat-loving ticks. For example, Ixodes inopinatus from the Mediterranean has now spread to Denmark. "

The big question is now with the two Hyalomma species, whether it is still about individual introduced specimens or whether the species have established themselves here.

"In another species, the brown-tailed dog tick Rhipicephalus sanguineus, originally from Africa, specimens have been found on dogs that never left their farm," says Prof. Dr. med. Mackenstedt.

"So they could not be an unintentional holiday souvenir - an indication that the species may already be developing here."

Exotic species could establish themselves in Germany

For the hyalomma species, this must be observed in the future. "We know how long the period the animals need for their development," Dr. Chitimia-Dobler.

"This allows us to assess whether they can establish themselves in Germany in a further global warming with increasingly dry and hot periods."

The expert traces the occurrence of hyalomma ticks in Germany back to the hot, dry summer of 2018.

"These ticks prefer a lower humidity than the ticks we find here. This year, the local weather comes very close to the living conditions of these ticks. "

The pathogens for Lyme disease and TBE have not previously been detected in Hyalomma marginatum and Hyalomma rufipes.

But even these bloodsuckers pose risks. Both species are considered to be important transmitters of Crimean Congo hemorrhagic fever, Arabic haemorrhagic fever and a form of tick-spotted fever.

"In one of the specimens found, we were able to prove the causative agent of a tropical form of tick-spotted fever. But at least dangerous viruses as pathogens of haemorrhagic fever forms have not been discovered so far, "said PD Dr. med. Gerhard Dobler, physician and microbiologist at IMB. (Ad)