Avian flu in American milk | Should Canada be alarmed?

While one in five containers of milk contains fragments of the virus responsible for avian flu in the United States, Canadian authorities are still not considering testing pasteurized milk. But the Canadian Food Inspection Agency has asked Health Canada to assess whether the virus could be found in contagious form in raw milk cheeses.

Should we be concerned about the presence of viruses in milk?

No, but results from the United States Department of Agriculture (USDA) released this week show that a large proportion of the country’s cows carry the virus that causes highly pathogenic avian influenza H5N1, but do not have symptoms, according to Richard Webby, an avian flu specialist at St. Jude Hospital in Tennessee.

At the Canadian Food Inspection Agency (CFIA), veterinarian Geneviève Toupin explains that these fragments of avian flu virus are probably not contagious. “Pasteurization eliminates viruses that are much more resistant than H5N1. »

On Wednesday, the CFIA told Toronto Star that it is not currently testing Canadian milk because no cow has tested positive for H5N1. The Press asked Friday if that policy had changed, and the CFIA couldn’t answer.

To be certain that the virus cannot be transmitted through the consumption of pasteurized milk, the USDA is doing further testing of these virus fragments detected in commercial milk. These more advanced tests involve putting the virus fragments present in milk in various growth media, to see if they are inert or if they can grow.

According to Daniel Lucey, an infectious disease specialist at Dartmouth College in New Hampshire who has been interested in H5N1 for more than 25 years, the two growth media used by the USDA to confirm that the virus fragments are not infectious are eggs containing chicken embryos, and canine kidney cell broths. “If it is infectious, the virus will grow in these two environments,” says the D^r Lucey.

The Union of Agricultural Producers of Quebec preferred not to comment on the issue of H5N1 tests targeting pasteurized milk, leading The Press to the Dairy Farmers of Canada, who in turn led The Press to the CFIA.

Why worry about raw milk cheeses?

In cows, the virus is mainly present in the mammary glands, explains the D^D Geneviève Toupin. “It may be transmitted between cows during milking. » So it could, without pasteurization, be transmitted to humans.

“We asked Health Canada if the acidification that occurs during the production of raw milk cheese destroys the virus,” says the D^D Toupin.

Health Canada could not say on Friday when it would have completed its analysis, according to public relations officer André Gagnon.

Are Quebec raw milk cheese producers worried? “We are monitoring the situation closely,” says Adèle St-Jacques, of the Quebec Dairy Industrial Council.

Is the presence of H5N1 in the mammary glands new?

“It’s not that surprising,” said the D.^D Toupin. Colleagues are currently doing a literature review and this has been mentioned for other strains of influenza. »

What type of surveillance is done in Canada?

Avian flu was detected in American cows, first in Texas at the end of March, due to an abnormal drop in milk production.

The CFIA has asked veterinarians across the country to test cows producing less milk for H5N1, but only after ruling out other causes. The CFIA could not specify on Friday how many H5N1 tests had been done on Canadian cows.

There are also no restrictions on imports of beef and live cattle, although on Thursday Colombia announced such restrictions for U.S. cattle.

“We consider that the import requirements are effective,” said the D^D Toupin. One of the import requirements is that the animal shows no clinical signs of disease and that in the 60 days before importation it has not been part of a herd where there was disease. »

This week, the USDA mandated H5N1 testing for all cattle moving from one U.S. state to another. “We think that this also applies to exports to Canada,” says the D^D Toupin. We are in the process of verifying it. »

The USDA also made reporting of bovine cases of H5N1 mandatory. “This is already the case in Canada for all animal species,” says the D^D Toupin.

This mandatory declaration should increase the number of infected herds recorded in the United States, according to the D^r Webby.

Canada could be protected by the fact that cows there spend less time outside in winter and early spring than in the southern United States, where most cases have been detected, according to Jean-Pierre Vaillancourt of the Faculty of Veterinary Medicine of the University of Montreal. “And farms in Quebec have fewer cows, less than 100 on average, compared to several thousand in certain American states,” he notes.