Canadian dairy producers on alert as bird flu spreads north – Farmtario Achi-News

Canadian dairy farmers have been urged to watch for symptoms in their herds and avoid unpasteurised milk as authorities in the US have reported a number of cases of mammals on dairy farms infected with Highly Pathogenic Avian Influenza (HPAI ). That includes mainly dairy cattle, but also barn cats and one human.

“Dairy Farmers of Canada has been working closely with the Canadian Food Inspection Agency (CFIA) as this situation has developed,” said a message sent by Dairy Farmers of Ontario (DFO) to the province’s licensed producers. “In addition to the biosecurity measures you are already implementing on the farm through ProAction, CFIA has recommended additional steps that can be taken.”

Why it’s important: Although experts on both sides of the border emphasize that the cases probably do not represent a significant change in the trajectory for the ongoing cases of HPAI, there is also agreement that vigilance is needed.

“This infection does not change the human health risk assessment of H5N1 avian influenza for the general US public, which CDC considers low,” explained an April 1 news release from the Centers for Disease Control and Prevention (CDC) in the US. The press release followed the detection of HPAI in a human who was in regular contact with dairy cattle in Texas.

It marks the second human infection from North America by this current HPAI strain, which has spread globally since its emergence in 2020. The first outbreak occurred in 2022 in Colorado during the culling of a flock of infected poultry.

Ontario Veterinary College Professor, Dr. Scott Weese, some context for the US agency’s guarded response to the recent discoveries on his Worms & Germs blog.

“This is bound to get a lot of attention,” Weese wrote in response to the human infection in Texas. “To a large extent, it’s fair, but it’s probably going to get crowded.”

He said that the only clinical sign the infected individual developed was conjunctivitis (ie redness and swelling around the eyes), which indicates that the disease was milk in this case. The person has been told to isolate and is being treated with an antiviral drug.”

The OVC vet also noted the apparent mildness of symptoms in cows and cats, emphasizing that the “highly pathogenic” label attached to this strain is specific to poultry. “It’s possible that (dairy farm infection) happened several times and we didn’t know because it wasn’t known that the cattle were infected, the person’s disease was mild and, because of that, there were no tests. That kind of context is important, but often lacking with emerging issues.”

Theoretically, the greatest risk from mammals infected with HPAI is that if the virus were to spread from one animal to another, it could potentially transform itself into a strain that causes severe or fatal symptoms – in the that species or in other mammals.

The bovine outbreaks in the United States appear to have developed from contact with infected wild birds and so far, the risk of viral transformation in the wild bird-to-cow outbreaks appears to be negligible.

Weese wrote that cattle do not have a species-specific strain of influenza A, “and they are not prone to be highly susceptible to influenza viruses from humans, pigs and other species, so recombination is less of a risk at this point this, at least. in cattle.”

However he agrees with the calls for vigilance among milk producers – partly to protect the dairy herd from infection but more importantly to prevent the spread of the virus among mammals in general.

“Human infections have been surprisingly rare given the extent of infections in myriad other species around the world (from this strain of HPAI), but we know they can happen,” Weese wrote. “More contact with infected animals means more risk of exposure.”

Interactions between HPAI and similar mammalian viruses, he added, “create the potential for the emergence of a new virus with the ability of a human flu strain to spread widely in humans, but one against which we have no population immunity to help.” n protection. “

“Sitting back and just ‘hoping’ it won’t be a problem is a dangerous proposition,” Weese wrote, adding that one of his biggest concerns is if HPAI shows up in cattle on a mixed farm and eventually finds its way into pigs. – who may be highly susceptible to flu viruses.

“As always with emerging diseases, we need to balance proactivity and practicality, by liberally applying the precautionary principle without going overboard and panicking.”

Taking its cue from the CFIA, DFO advised its members to watch for symptoms of HPAI in cattle, including reduced feed intake, reduced milk production, abnormal manure, thickened milk (especially milk that shows little positive response to mastitis tests) and possibly fever.

If symptoms are detected, contact your vet and divert milk from affected cows away from the bulk tank.

DFO’s message to producers also urged them to “remain vigilant about who and what is coming to your farm.” Specifically:

• reduce cattle access to any areas that may attract waterfowl, such as free feed, nesting areas, or wetland bird boxes
• don’t go into barns wearing boots worn off the farm
• restrict access to people who have been in sensitive areas, especially the United States