Dengue fever is on the rise in parts of Europe with experts linking local outbreaks to an invasive species of mosquito.
But with travellers heading to the region for summer, scientists and medical professionals say that though the risk is low, there are still things you can do to stay safe.
According to the European Centre for Disease Control and Prevention, several countries have reported a substantial increase in the number of imported dengue cases and while local cases for 2024 are not yet known, there’s concern the recent rise could be a sign of what’s to come.
The agency pointed to aedes albopictus, also known as the Asian tiger mosquito, setting up shop in at least 13 European countries, including Greece and France.
“The observed rise in the number of locally-acquired cases of dengue in Europe is of concern as it shows the environmental conditions in Europe have become suitable for the transmission of the virus,” Celine Gossner, ECDC principal expert in emerging and vector-borne diseases, said in an email. “We can expect to see more outbreaks within Europe and possibly larger outbreaks.”
The ECDC reports between 2010 and 2021, there were 73 locally acquired cases for the entire period.
Yet in 2022 there were 71 reported that year, and 130 cases just last year, what the agency calls a “significant increase.”
In addition, the number of cases to come into Europe is also rising, with more than 4,900 cases in 2023, a sharp increase from 1,572 in 2022 and the highest number reported since the start of surveillance at the European Union level in 2008.
Dr. Michael Libman, director of the Tropical Diseases Centre at McGill University, told Global News in an interview he’s not surprised by the rise.
“Dengue is definitely on the march around the world,” he said. “We’re definitely seeing it spread to pretty much not just the whole tropical world, and not even the whole what we call the subtropical world, but actually the places that we would consider to be pretty relative temperate places.”
That includes southern Europe and the southern U.S.
What are the symptoms of dengue fever?
Dengue is spread by female mosquito bites and according to the Canadian government can cause flu-like symptoms.
“The bottom line is it’s fever, and it’s feeling crappy, tired, fatigued, lots of aches and pains in general, you may have rashes of different kinds,” Libman said.
“Sometimes it makes you more than miserable for more than a few days and sometimes it gets complicated and you can have all kinds of problems with different organ systems. And yes, in rare cases it can be fatal.”
The ECDC says those who contracted dengue in Europe locally have had mild symptoms, with no deaths reported.
Protecting yourself if travelling
With summer underway, many travellers including Canadians may still look to get out of the country by visiting sunny destinations.
Travel agents told Global News Europe is becoming a big destination with Flight Centre saying they saw demand for the region for summer start even in January.
If you are heading to southern Europe this summer, the ECDC says the risk for tourists contracting dengue is still “very low” due to the size of outbreaks seen.
Libman notes if trying to stay safe, wearing clothing designed to block out mosquitos like certain camping gear or using repellants like DEET can help.
But scientists like University of Toronto Mississauga assistant professor in biology Rosalind Murray say the tiger mosquito differs from the species we see in Canada, so there’s other precautions to take.
“So North Americans especially, who are used to our more temperate species that come out mostly to bite humans in the evenings, they’re going to be more vulnerable during the day because we’re just not used to seeing mosquitoes at that time of day as much,” she told Global News.
Could Canada see a dengue spread like Europe?
Dengue fever has been seen in Canada, with Public Health Agency of Canada senior scientist Victoria Ng noting it ranges from about 200 to 300 cases yearly. Every year, she said, is a result of imported cases with no locally-acquired cases reported.
That’s not to say a spread like what’s being seen in Europe couldn’t happen here though, though several things would have to happen first.
Canada’s species for one thing cannot transmit or be infected with the disease, so there would need to be another way to transmit it such as a locally-established population of the tiger mosquito.
Ng notes there is a small group of said insect found in Windsor, Ont., but due to the size of that region and small amount of this bug transmission likelihood is low.
In addition, however, Ng notes the virus would need to be introduced and as it’s not circulating in Canada, an infected traveller would need to return to Canada, be bitten by a mosquito that can transmit it and then for it to “take a blood meal from an individual in Canada that has not had the virus and has no history of travel.”
“A lot of things have to fall into place, and it has to all happen in the same time, in the same geographic location,” she said.
It’s not to say it couldn’t happen, but while Ng says Canadians should still take precaution over mosquitos abroad or here at home, it’s unlikely the spread being seen in Europe will happen for the time being.
— with files from Global News’ Katie Dangerfield and Katherine Ward
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