Recent reports coming out of the U.S. of avian influenza virus (H5N1) being found in cattle has been garnering attention. First noted in mid-March as a “mystery illness” when a handful of dairy farms saw a drop in milk production and low appetite amongst some of their herd, traction on this story has grown as additional states began reporting cases.
As cases were found in goats, a handful of farm cats, and even a farm worker, further media outlets picked up the story. Cases have now reached as far north as our neighbouring states, Idaho and Michigan.
University of Calgary Faculty of Veterinary Medicine (UCVM) researchers are urging the community to stay informed, but not to be alarmed by attention-grabbing headlines.
UCVM researcher and poultry veterinarian Dr. Faizal Careem, PhD, has been studying avian influenza virus for the past decade. Recently, he has been focusing his work on highly pathogenic avian flu viruses (HPAI), to which H5N1 belongs, and its spillover from wild waterfowl into commercial poultry operations.
In this time, he has seen spillover into mammals like foxes and skunks. These spillovers are usually found in animals that come into direct contact with infected wild birds, such as carnivores, or even your everyday indoor/outdoor cat.
While these spillovers are concerning, it is essential to clarify that the “highly pathogenic” classification pertains to its impact on poultry and does not necessarily indicate a similar effect in humans or other mammals. Current genomic evaluation of the virus from cattle has not shown any apparent changes that would make it more transmissible to or between mammals, and the risk to the general public at this point is low.
Considering the millions upon millions of birds worldwide infected with HPAI, the handful of cases in mammals that we have found is negligible. However, our known cases may not be showing the true story. Most animals die without necropsy (autopsy for an animal). The few feline cases that have resulted in death, that we know of, are very possibly rare outliers in a field of “get sick and get over it”-type cats. The recently found case of H5N1 in a dairy farm worker resulted simply in pink-eye-type symptoms. Despite over 80 million chickens exposed to H5N1 culled in the U.S. since 2021, we have seen only two cases transferred to humans, both of whom were working directly with infected animals and recovered from minor symptoms quickly.
Currently, our biggest concern is limiting the spread. For the average person, this isn’t going to have much effect on our lives. As flu viruses are not very stable, without direct contact they generally don’t transmit well. That means that risks of contamination in the food supply are currently low.
The pasteurization and processing of dairy items like milk and cheese are incredibly effective at killing off most potential contaminants, including flu viruses. At this point, unless you are handling infected animals without any protection, you’re pretty safe.
Our first line of defence right now are the producers. Dr. Karin Orsel, DVM, MSc, PhD, Dipl. ECBHM, provides advice to this group: “While we need to remain watchful, livestock owners are encouraged to increase biosecurity measures to minimize direct and indirect (fecal contamination of water and feed) contact with reservoir host, wild waterfowl, and not transport suspected animals unless necessary.”
An important first step in catching endemic and emerging diseases is diagnostic testing. UCVM is home to the Diagnostic Services Unit (DSU) and the Veterinary Outbreak Investigative Service (VOIS). These units are supported through provincial funding to investigate routine deaths and unusual outbreaks in our livestock species. At the front lines of outbreaks, they work alongside producers to ensure the health of our livestock and food supply.
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