Canada expanding surveillance, testing milk for H5N1 avian flu amid U.S. dairy cattle outbreak
Changes announced Friday night follow scientists' concerns about unprecedented spread of virus in cows
Federal officials say Canada is expanding its surveillance for a dangerous form of avian flu amid a growing outbreak of H5N1 in U.S. dairy cattle, with monitoring efforts now set to include testing of milk being sold on store shelves.
The Friday night update comes just days after leading Canadian researchers questioned the country's response to the unprecedented spread of the virus among cows south of the border — including the discovery of viral fragments in processed milk.
"The Canadian Food Inspection Agency (CFIA), the Public Health Agency of Canada (PHAC) and Health Canada are monitoring this situation closely and would like to reassure Canadians that commercially sold milk and milk products remain safe to consume," said the CFIA in its statement.
Milk from dairy cows in Canada goes through pasteurization before being sold, a heating process that neutralizes harmful pathogens like bacteria and viruses.
As noted by the CFIA, the U.S. Food and Drug Administration recently announced its latest research shows pasteurization is indeed effective in inactivating H5N1, even when fragments of the virus remain.
The CFIA had previously said that the agency was not testing any milk, but announced on Friday that Canada will now be "conducting enhanced testing of milk at the retail level" to look for any viral fragments that could signal cases appearing in dairy cattle here.
This form of avian flu is a reportable disease in Canada, the statement continued, which means anyone suspecting a case in animals, including poultry or livestock, must report it to the CFIA. Confirmed and probable human cases are also reportable to PHAC.
While Canada hasn't had any human cases to date, tens of millions of birds have been infected by the virus, including poultry on various Canadian farms.
In its statement, the CFIA said Canada is also expanding its surveillance to manage the "possible emergence" of avian flu in cows by requiring negative test results for lactating dairy cattle being imported from the United States to Canada and "facilitating the voluntary testing of cows" that aren't presenting with any symptoms.
Speaking to CBC News in recent days, multiple Canadian scientists have also called for random testing of farm workers, wastewater surveillance and other proactive measures to try to catch potential H5N1 infections as quickly as possible.
Several did commend the CFIA for taking more action through its latest update.
"All the data from the [U.S.] so far suggests that this outbreak has been spreading quietly in cattle for months and has spilled back into birds and other species, including humans. It's critical that we make every effort to determine if we are facing a similar situation in Canada," said Angela Rasmussen, a virologist with the University of Saskatchewan's Vaccine and Infectious Disease Organization.
"Active surveillance and safeguarding our food safety is critical to containing this emerging threat and I'm relieved that both CFIA and PHAC agree that is a priority."
Dr. Isaac Bogoch, an infectious diseases specialist with the University Health Network in Toronto, also called Friday's announcement "a step in the right direction."
"Given the significance of H5N1, I would have thought there would be a more rapid, proactive, and broad approach to case detection," he said.
So far, avian influenza has been reported in 36 dairy cattle herds across nine U.S. states, plus one human case in Texas linked to the outbreaks, though scientists say there are likely more animal and human infections that haven't yet been identified.
"If the CFIA becomes aware of any potential food safety or animal health risks, immediate actions will be taken to help protect Canada's food supply and livestock," the agency's statement noted.
"These measures complement the existing comprehensive and integrated approach to human surveillance of influenza in Canada, and will inform and support the range of ongoing preparation actions undertaken by PHAC with its partners to protect human health."
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