Hospitals testing for H5N1 avian flu as virus season ramps up

As respiratory season ramps up in Ontario, hospitals are being asked to take extra steps to screen patients for avian influenza.

That enhanced surveillance, which began earlier this year, has taken on a new urgency with the confirmation of Canada’s first domestically acquired case of avian influenza, in a British Columbia teenager. The teen, who was in intensive care with acute respiratory distress, had no known contact with infected livestock, including any of the B.C. poultry farms where birds have been infected. A family dog that had been ill tested negative for avian flu, officials reported. The case was identified earlier this month.

Genotyping of the highly pathogenic H5N1 bird flu that infected the teenager shows the virus had undergone mutations that would make it easier to infect people, according to scientists. The virus is similar to a strain that has infected poultry.

The case has put health officials and pandemic experts on alert. H5N1 is considered a pandemic threat if the virus mutates enough to allow sustained human-to-human transmission, something that has not been reported. Experts say its continuing spread through livestock, wild animals and humans in recent months heightens that risk. Health Canada says the risk of avian influenza infection for the general population in Canada remains low, but it is higher for those who have unprotected exposure to infected animals.

The most recent avian flu outbreaks in poultry in Canada have largely been in the western provinces, mainly British Columbia. But earlier this week, highly pathogenic avian influenza was confirmed in commercial poultry in the area around Saint-Hyacinthe, just east of Montreal, according to the Canadian Food Inspection Agency. A second possible outbreak is being investigated in Quebec.

In addition, Public Health Ontario said in a recent update that it is “currently responding to cases of highly pathogenic avian influenza (H5N1) in birds across Ontario.” Earlier this year, avian influenza was identified in crows and waterfowl in the Ottawa area, among other parts of the province.

With the start of the spread of seasonal flu along with other respiratory diseases in Canada, surveillance for possible cases of avian influenza in humans could become more complicated. And pandemic experts say the risk of reassortment, which could increase the threat to humans from avian influenza, goes up when seasonal flu is circulating. Reassortment can occur when two different influenza viruses infect the same cell and exchange gene segments, creating a virus with a combination of genes from both viruses. 

Provincial health officials are asking hospitals to conduct further tests on patients who have tested positive for seasonal influenza, or send samples to Public Health Ontario, to see if they have avian flu and, if so, for genotyping. That includes all ICU patients who have tested positive for influenza. They are also being told to screen hospitalized patients with flu-like symptoms for potential exposure to infected birds or mammals. That could include wild game or birds, hobby farms, raw milk or livestock, according to a memo from the office of Ontario’s Chief Medical Officer of Health.

Hospitals had been asked to conduct extra surveillance for possible avian flu cases in the spring and summer after highly pathogenic avian flu began circulating in cattle and in some farm workers in the U.S. That surveillance was scheduled to end in September with the arrival of seasonal flu season.

This fall, Ontario’s associate chief medical officer of health Dr. Michelle Murti said in a memo that it is necessary to continue extra surveillance for hospitalized patients “to maintain our ability to detect novel, non-seasonal influenza amidst circulation of seasonal influenza virus.”

She said the enhanced surveillance is necessary “due to the evolving risk of HPAI (highly pathogenic avian influenza).”

Trying to identify rare case of avian influenza at a time when seasonal influenza and other respiratory viruses — including COVID — are circulating, could present a challenge to hospital staff.

Some cash-strapped hospitals are already struggling with the potential cost of testing patients for COVID-19 on their existing budgets, after the province stopped special funding all COVID-19 testing, sources said. A spokesperson for Health Minister Sylvia Jones said COVID-19 testing is now considered “part of regular hospital operations,” although hospitals received a one-time payment for it for 2024-25.

Still, several hospital sources say it is adding to the financial pressures they are facing. Many Ontario hospitals have reported deficits in recent years.

In a statement, Anthony Dale, president and CEO of the Ontario Hospital Association said it has heard concerns from some hospitals “regarding the cost of ongoing COVID-19 testing.” He also said the OHA and its member hospitals are working to find funding and operation solutions “that create a more innovative and sustainable future.”

Since early this year, there have been outbreaks of avian flu in dairy herds in numerous U.S. states and farm workers. In recent weeks the vast majority of cases have been reported in California. The spread of the avian virus to cattle has surprised many experts and raised concerns about its growing potential to become a pandemic.

The human cases in the U.S., mostly involving agricultural workers, have been mild, mainly involving conjunctivitis in the eyes.

But experts said people should not be lulled into thinking that the highly pathogenic avian influenza (H5N1) is mild in humans. Historically, cases that have jumped from birds to humans have been fatal at least half the time, although that is likely overstated because milder cases would likely have been missed.

“I have been very uncomfortable since the cattle outbreak in the U.S. to me that was a turning point in risk,” said Matthew Miller, Canada Research Chair in viral pandemics and director of the Michael G. DeGroote Institute for Infectious Disease Research at McMaster University.

“Influenza has shown us five times since 1918 that it can cause a pandemic. It is a virus we know a lot about and the risk is high. It is very difficult to predict but I would rather be proactive than be complacent.”

Seasonal influenza rates remain low in Ontario, according to the most recent data available from Public Health Ontario. COVID-19 spread is moderate.

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