2023-05-04 11:42:00
A 62-year-old man was bitten by a tick while hiking through fields in Spain. Two days later, he fell ill and was taken to a hospital in Madrid, where his condition rapidly deteriorated. He died after nine days.
This happened in 2016 and proved to be the first death in Spain caused by Crimean-Congo Hemorrhagic Fever (CCHF), a tick-borne illness that starts with flu-like symptoms and can often lead to organ failure.
spread to the north
“Ticks are migrating across Europe with longer and drier summers due to climate change,” says Professor Ali Mirazimi, a virologist at the Karolinska Institute in Sweden.
The first case was difficult for Spanish doctors to diagnose because hemorrhagic fever had not previously occurred in Western Europe. A nurse at the patient’s hospital also contracted the fever but survived after weeks in intensive care.
Then came im July 2022 another man hospitalized in Spain with the same disease. Scientists are now warning that CCHF, which can kill between 10 and 40% of patients, is spreading north and west in Europe.
The disease is caused by a virus in a species of tick that feeds on small animals when young and migrates to larger animals, including grazers, as adults.
CCHF was first described in 1944 from an outbreak among soldiers in Crimea on the north coast of the Black Sea. Sporadic outbreaks continue to be recorded today, particularly in Africa, Eastern Europe, Turkey, Central Asia and India. The disease is spreading worldwide.
An infected tick can produce thousands of infected eggs. The young ticks feed on small mammals such as rabbits, but also on birds.
The connection to the birds allows the ticks to spread and introduce the virus to new areas.
Dangerous newcomers
“Once we find the infected ticks, we know that sooner or later there will be an outbreak,” says Mirazimi
The virus is currently found in ticks, for example in Italy, but there have not been any outbreaks yet. Its appearance in new countries is dangerous because it is difficult for doctors to detect the new disease in patients.
“We don’t have good medical cures,” explains Mirazimi. “There is no good antiviral, no approved vaccine and knowledge about the disease is incomplete.”
That means doctors have no choice but to rely on general medical care, which consists of fluids, medications, and critical care where necessary.
Another challenge is that a person infected with hemorrhagic fever can transmit the disease to close contacts through saliva and sweat. This poses a risk to family members as well as to the treating doctors and nurses.
The earlier the diagnosis is made, the better for everyone involved, because a rapid diagnosis allows for the proper isolation of patients.
Tests 1, 2, 3
All of this underscores the importance of a project led by Mirazimi called VHFMoDRAD to develop tests for this disease. Funded by the EU and industry, the initiative ran from 2019 to 2022.
One of the resulting approaches uses polymerase chain reaction tests (so-called PCR tests), which usually require sophisticated laboratory equipment and trained personnel. Here, however, the tests are placed in a special machine, which makes the process quicker and easier.
In another approach, the project developed easy-to-use tests, similar to the widely used rapid tests for Covid-19.
An added benefit of these tests is that they can detect not only CCHF but also other viral hemorrhagic fevers — a group that also includes Ebola, Marburg, and Lassa viruses. Only in February and March of this year were two different outbreaks of the Marburg-Virus reported in Equatorial Guinea and Tanzania.
However, the most famous virus is Ebola. This virus has in one outbreak, which began in Guinea in 2014, has infected more than 28,000 people. It spread to seven other countries and killed more than 11,000 people by the end of the outbreak in 2016.
Outbreaks of haemorrhagic fever in general need to be recognized urgently, says Professor Roger Hewson, expert on CCHF and other haemorrhagic viruses at the Liverpool School of Tropical Medicine in the UK.
“They cause a very high and devastating mortality rate,” says Hewson, who worked with Mirazimi on the VHFMoDRAD project. “With a quick diagnosis, patients can be quickly isolated and rescued.”
CCHF is not the only hemorrhagic fever caused by close contact, e.g. B. can be transmitted via saliva or sweat, so that other forms such. B. can be easily passed on in medical care or funerals.
This is exactly what happened in West Africa during the Ebola outbreak. Crucially, VHFMoDRAD has found a way to deactivate any virus present when the blood sample is taken, making testing for these diseases safer.
Historically, deadly Ebola outbreaks in remote communities in Africa have likely gone unreported. Thanks to better transport links, such viruses can now spread quickly in large urban areas.
Once the disease has been identified, patients can often be saved with appropriate treatment.
In Turkey, CCHF is so widespread that doctors can easily identify the disease and provide appropriate life-saving treatment to patients. According to scientists, the mortality rate for CCHF in Turkey is a relatively low 7%.
Hard fight
Viruses that cause hemorrhagic fever usually exist in animals such as bats — including Ebola and Marburg viruses — and rarely jump to humans. Once such infections occur, many people’s immune systems attack the invader so fiercely that fatal organ damage occurs.
“The viruses are often cleared from the body after a few weeks, but the immune response then causes bleeding,” says Hewson.
His lab studies CCHF to understand immune responses to the virus. This research feeds into another EU-funded project, CCHFVaccineto develop a vaccine.
This initiative, also led from Sweden, started in 2017 and is expected to be completed in June this year. So far, two types of vaccines have been pursued.
Studies on the safety of the vaccine are planned to be carried out in Sweden later this year or early 2024 as part of further research planned. Phase III trials to prove the vaccine’s effectiveness could then be conducted in Turkey.
The vaccine would be for the most vulnerable people exposed to the virus. This includes doctors, nurses, veterinarians, slaughterhouse workers and maybe even tourists in endemic areas.
Although CCHF is still rare in Europe, it poses a major challenge.
“The consequences are really enormous for anyone who gets infected,” says Mirazimi.
Further information
–> EU-funded health research and innovation
Article by Anthony King
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