It can spot its prey from up to 200 metres away — but unlike many other species, it does not lie in wait in the grass for a victim to come closer. Instead, it runs after it, chasing animals and humans alike.
The Hyalomma tick, often called “the great hunting tick”, was previously found mainly in Africa, Asia and southern Europe. But climate change means it can now survive further north, and it has already been spotted in Germany and several eastern European countries. Kosovo, in south-east Europe, has been a hotspot for the tick for some time.
The Hyalomma tick is also a carrier of the highly pathogenic virus that causes Crimean-Congo haemorrhagic fever, a potentially deadly disease with a high fatality rate. Symptoms are comparable to those of Ebola fever or the Marburg virus. The virus can destroy blood and lymph vessels, which can lead to internal bleeding and death.
Kurtesh Sherifi first read about Crimean-Congo haemorrhagic fever in a newspaper in 2005, when he was completing his studies as a veterinarian in Berlin. The article said that 11 people in his homeland, Kosovo, had contracted the disease and five had died. He was already interested in pathogens that can be transmitted between animals and humans, known as zoonoses, and Crimean-Congo fever intrigued him.
Back home, Sherifi began working with the faculty of agriculture and veterinary medicine at the University of Pristina. But the budget for research was tight. Kosovo, a small country with only about 1.6 million citizens, did not have a high-security laboratory or the equipment needed to investigate the Crimean-Congo fever virus.
Seeking German cooperation
Sherifi contacted Germany’s largest institution for research in this field, the Bernhard Nocht Institute for Tropical Medicine in Hamburg.
One of the researchers was Petra Emmerich, a virologist and expert on so-called Risk Group 4 viruses — viruses that cause severe, often fatal diseases and usually have no widely available treatment. The Crimean-Congo virus is in that risk group.
Emmerich also acts as a reservist in the German military, which is particularly interested in viruses that could be used as biological weapons. She was sent to Kosovo in 2009, when she met Sherifi.
A lively exchange began between the researchers. In Kosovo, a structure was established to monitor the spread of the Hyalomma tick and the virus. In 2013, the researchers’ joint work began to receive funding through the German Biosecurity Programme, run by the country’s Foreign Ministry and “intended to help partner countries tackle biological threats.”
“It’s give and take,” said Emmerich of the scientific partnership. “We have the diagnostic expertise and the necessary resources but we don’t have the patients.” Doctors from Germany regularly come to Kosovo with Emmerich, where they can exchange information with their counterparts there.
Raising public awareness is another important pillar of the Germany-Kosovo cooperation.
Farmers in Kosovo are particularly susceptible to infection — and not solely because ticks bite them, but because they often use their bare hands to remove ticks from animals. If infected blood from the animals gets into a small wound on the human hand, the virus can be transmitted to the human.
“This is quite likely how a large proportion of the [infected] population in Kosovo got infected,” Sherifi explained.
Patients require intensive care, isolation
He and Emmerich have visited schools to educate students about the dangers of the virus and how to protect against it. For example, certain tick repellents help, as do long trousers and sturdy shoes.
Not all Hyalomma ticks carry the virus, and most people who are bitten by a Hyalomma tick do not become ill. However, the bigger problem is that there is neither a vaccine nor any specific treatment for those who do suffer from Crimean-Congo fever.
“If you do get sick, it’s particularly severe,” Emmerich explained. The disease begins with non-specific, flu-like symptoms including fever, chills, aches and headaches. In severe cases, a patient will begin bleeding from the skin, nose and gums and may also experience gastrointestinal bleeding. The worst cases can result in organ failure.
Patients require intensive care and isolation because they are highly contagious.
Much of the treatment in intensive care focuses on maintaining a patient’s vital functions, but they are also given the antiviral drug ribavirin. But, as Emmerich said, “ribavirin is not all that effective in acutely ill patients.” That is something the scientists have seen at first hand with cases in Kosovo.
The best answer is prevention, which is why it is also very important for the researchers to monitor the spread of the Hyalomma ticks and to recommend avoiding certain areas where the ticks are prevalent, if possible.
Successful tick tactics
Over the years, the researchers have not only collected thousands of the ticks, but they have also carried out so-called seroprevalence studies. These use blood tests to find antibodies from past infections. This allows the scientists to determine whether humans or animals have come into contact with the virus.
Farm animals are particularly suitable for this type of study, Sherifi said, as the virus does not affect them. And unlike wild animals and humans, they usually remain in a clearly defined area. That means that if antibodies are detected in the blood of these animals, it is clear the virus is circulating in that area.
In Kosovo, the number of serious infections has dropped drastically in the past decade, amounting to just five cases in total. In the previous decade, there were about 100 cases. Sherifi and Emmerich believe this shows how successful their work has been.
Of course, that does not mean the ticks and the virus will not spread further in Europe, and the researchers both expect this to happen.
Hyalomma ticks with the Crimean-Congo virus have just been detected in France although, so far, no humans have been infected there.
“Over the past 13 years, Hyalomma ticks have spread geographically,” said Emmerich. “As a virologist, that’s something to think about, and it needs to be closely monitored.”
This is why it is important for the German and Kosovar scientists to pass on what they have learned to countries that have not yet had as much experience monitoring the Hyalomma ticks, such as North Macedonia and Albania.