In case of Seasonal flu SurgeHealth officials closely monitor a growing threat – the potential fusion of human And bird flu strains.
Indeed, if the viruses mix, it could give birth to a new highly contagious and deadly pathogen, arousing fears of a world pandemic.
Flu cases have increased in Canada in recent weeks, as well as avian flu reports Infect birds such as Canadian geese. And as spring migration brings more birds to the country, they can potentially win the avian flu virus with them.
More human influenza It is there, the more likely it is that the virus can mix with the bird flu and create a new virus that has a “pandemic potential”, explained Matthew Miller, director of the Degroote Institute for Infectious Disease Research McMaster University.
He added that a bird flu pandemic is currently prevented by its limited capacity to spread from man to man.
“However, the seasonal flu is obviously very good from man to man. The concern is that if an avian flu and a human flu should mix their genetic material, avian flu could maintain the serious illness it causes but acquire well to spread between humans like this seasonal flu, “he declared.
Currently, the human risk of bird flu remains low, but the Canada Public Health Agency (PHAC) said that whenever the virus jumps to a new species, it increases the risk.
Human infection through avian flu is rare and generally occurs after close contact with infected birds, other infected animals or highly contaminated environments.
In November, a 13-year-old girl from British Columbia was hospitalized with an avian flu and tested positive for the H5N1 B.2.3.4.4.4B clade and the genotype D1.1, the same clade and the same genotype detected in wild birds in British Columbia, as well as in epidemics in poultry farms in the province .
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Kerry Robinson, the The vice-president of the branch of infectious diseases and vaccinations of Phac, said that the agency continues to monitor the evidence of avian flu in the world.
“We see that individuals who have exposure to animals, infected animals have a higher risk of avian flu. But as a whole, the risk remains low, “she said.
But she pointed out that influenza viruses continue to evolve in animals and have the potential to also adapt to humans.
How human flu could modify the bird flu
The influenza virus has a genome made up of eight separate RNA segments, much like individual cards in a deck, said Miller. This unique structure allows the flu to quickly exchange genetic equipment with other influenza viruses, allowing it to quickly acquire new lines and adapt.
Imagine a card game, said Miller. A human influenza virus has eight club costume cards, while a bird flu virus has eight cards in the heart combination.
If the two viruses infect the same cell – often in an animal like a pig, which acts as a mixture ship – Their genetic equipment can reshape as a card game. The new virus still needs eight cards, but now it could have a mixture of clubs and hearts, which means that it carries genes of human flu and birds.
It is dangerous, he said, because the virus can quickly earn new features, such as the ability to propagate more easily or to become more deadly.
“This process is the way in which the anterior influenza pandemics in the past have started … Two different flu viruses infect a host,” said Miller.
“In the case of 2009, the Porcine flu H1N1. These are in fact three viruses that mixed their gene segments or their card game, avian flu, porcine flu and human flu. And this is what led to the H1N1 2009 pandemic. ”
There is no evidence that human flu and birds viruses have mixed. However, different avian influenza strains have already combined their genes.
For example, the current H5N1 virus causing epidemics in poultry and dairy cattle in Canada and the United States come from two different viruses: H5N6 and H5N8. Thanks to a genetic mixture between different strains of avian flu, this virus has evolved in the H5N1 strain.
Although the probability of mixing the bird flu with the human flu decreases during the summer months of North America, when the traffic of the seasonal flu is minimal, the risk does not disappear entirely, said Miller.
In the southern hemisphere, where the seasons are reversed, flu activity can always be spread, now the potential for viral interactions.
“The other concern is the detection and the ability to distinguish possible cases of avian flu from the seasonal human flu,” said Miller.
“They generally cause respiratory infections and are characterized by common symptoms to which we all think, such as coughing, sore throat, sometimes flowing nose and sneezing. With flu, we also tend to see more systemic symptoms. Thus, things like fever and fatigue and muscle pain. »»
A notable difference in symptoms when a person is infected with the bird flu is severe conjunctivitis or a pink eye. This symptom is rare in seasonal flu, which makes it a key warning sign for doctors that something unusual can happen, he noted.
And although the risk for the public remains low at the moment, Miller said: “The problem of the risk of influenza pandemics is that it is not necessarily a slow risk gradient increased over time. We could go from a bit like very low risk today at a huge risk in a week. »»
– with Global News’ Katherine Ward files
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