Doctors concerned about potential spread of bird flu in Canada

H5N1 or avian flu has been detected at dozens of dairy farms in the United States and Canadian experts are urging surveillance on the north side of the border.

“We should be actively looking for it,” said Dr. Isaac Bogoch, infectious diseases specialist at Toronto’s University Health Network.

Bogoch says the number and diversity of mammals that have been affected by H5N1 this year has jumped dramatically.

“If more mammals are infected, the virus can obviously change and be more readily transmitted between mammals,” warns Bogoch.

Matthew Miller, from the McMaster Immunology Research Centre in Hamilton, says the mechanism that kept bird flu mainly in birds has suddenly made the transition to spread more readily in mammals, ranging from dogs and cats, cows, goats and sea lions.

But does that mean it will inevitably become widespread in humans?

“No, It’s not inevitable” says Miller. “But the risk, I would say, is profound.”

Miller points out no illness has caused more pandemics in recent history than influenza, citing the so-called Spanish flu pandemic in 1918, and flu pandemics in 1959, 1968, 1977 and most recently, swine flu in 2009.

The recent dairy farm outbreaks in the U.S. have prompted food inspections in ground beef and grocery store milk, with the Food and Drug Administration finding that one in five dairy samples tested was positive for H5N1 particles.

Bogoch points out the virus fragments are not able to cause illness in humans.

But in cats, fed raw milk at U.S. dairy farms, there was a high mortality rate, with upwards of 50 per cent of the cats who tested positive for H5N1 dying of the virus.

U.S. and Canadian dairy officials say pasteurization destroys the pathogens in milk and they urge consumers not to drink raw milk.

“Canadian dairy producers already adhere to some of the highest biosecurity standards in the world. It should be noted that only milk from heathy animals is authorized for distribution and for human consumption," Dairy Farmers of Canada added.

Miller says surveillance in Canadian poultry farms is already well established, but he wants active surveillance brought in for dairy operations, before we start seeing human cases of avian flu.

“I think systematic surveillance in cattle in Canada is warranted at this time, given what we know the risks are in the U.S.”