Avian flu is on the rise in Canada: What to know about human infection of H5N1
Experts say the potential for a "spillover" of the virus to humans is now a "critical concern."
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Bird flu — also known as avian influenza virus — has been spreading across Canada killing millions of wild and domestic birds since 2021. Now, experts say the potential for a "spillover" of the virus to humans is of "critical concern."
Matthew Miller, Ph.D, scientific director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University, said avian influenza virus is "very dangerous" for humans who come in contact with it because of the "extremely high mortality rate."
"While many people think that the H5N1 avian influenza virus only poses a risk to birds, that isn’t true," Miller explained.
The virus has already been a serious threat to commercial flocks, but has started showing up in a variety of different mammals lately, including the infection of a domestic dog last month in Ottawa.
Now, new Canadian research shows that the highly pathogenic strain of avian influenza H5N1 is able to spread quickly and "efficiently" among ferrets — a mammal often used to evaluate the risk of human transmission of a virus. Similarly to birds, the infection in ferrets resulted in lethal outcomes.
What exactly is avian influenza virus?
According to Health Canada, the predominant avian influenza H5N1 viruses that are now circulating globally are different from earlier H5N1 viruses.
"Avian influenza viruses continually change, which can affect how easily the virus spreads from birds to other animals, including humans, and also how severe the illness is," a media representative said in an email to Yahoo Canada.
McMaster's Miller explained the H5N1 influenza virus is a type of virus that naturally infects birds.
"When birds migrate or congregate in fields or feed in waterways, during their migration, their droppings carry this virus," he said.
Those droppings can contaminate the water, the dirt, and food that other animals consume and infect more birds, and even other species.
"Unlike normal seasonal flus that typically cause mild respiratory infections, H5N1 influenza virus infections can spread throughout our bodies and infect tissues like our brains, our hearts, and other vital organs leading to really severe illness."
The Ontario Ministry of Health stated that based on studies of patients with H5N1 virus, symptoms of human infection include: fever, cough, sore throat, congestion, body aches, headaches, tiredness, red eyes, and shortness of breath. Less common symptoms can also manifest as diarrhea, nausea, vomiting and even seizures.
How common is human infection of bird flu?
Health Canada told Yahoo Canada that the risk of human infection with avian influenza (H5N1) is rare.
Since 1997, there have been more than 800 human cases of bird flu reported worldwide, mostly occurring in Africa and Asia. To date, there has only been one human case of H5N1 ever reported in Canada – when a Canadian resident died of avian influenza in early 2014 after returning from a trip to China.
The new study — which hasn’t passed peer review yet — warned that "while there have been few human cases of infection with clade 220.127.116.11b viruses reported to date, the potential for spillover, particularly of viruses harbouring mammalian adaptation signatures remains a critical concern."
The CDC has taken the data on bird flu spreading beyond birds seriously, announcing earlier this spring that there are already trials underway for a vaccine that could be used to protect humans if the virus continues to adapt.
How can people protect themselves from contracting H5N1?
The good news is that there currently is no evidence that H5N1 transmits effectively between humans who come in contact with each other.
Miller said people infected with H5N1 virus typically become infected by direct contact with an infected animal.
"H5N1 avian flu is not transmitted by eating chicken or turkey that (you) buy at the grocery store," he explained.
According to Miller, the best thing people can do to prevent infection is to avoid contact with sick or dead animals.
After coming home from parks or places where geese congregate, he also advised to be "extra vigilant about washing your hands." As an extra precaution, wash your shoes or any clothing that comes in contact with bird droppings.
Health Canada confirmed "avian influenza is not a food safety concern." It added "there is no evidence that eating fully cooked commercial poultry or eggs could transmit avian influenza to humans."
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