Highly pathogenic avian influenza has created a lot of headaches and heartache, not to mention a financial burden, for U.S. poultry producers since its 2014-15 outbreak.
As HPAI and influenza A virus subtype H5N1 continue to ravage various species of mammals, the concern has reached more livestock producers, as the virus made the leap to dairy cattle in early 2024. Minnesota’s first dairy detection came in June.
The more the livestock industry has learned about HPAI and H5N1, the more questions arise.
Researchers from the University of Minnesota College of Veterinary Medicine hope a $1.5 million cooperative agreement grant from the USDA will generate some answers for the plethora of questions being created, and to gain a better understanding of how the disease is transmitted to mitigate the impact it has on dairy herds and the agricultural industry as a whole.
Scott Wells, a professor in the CVM, is leading the collaboration among the research teams, working on nine projects at UMN that bring together experts in virology, epidemiology, microbiology, veterinary medicine and agricultural biosecurity.
One thing that Wells wants to make clear is that HPAI does not present a food-safety issue. “Food safety is not an issue, in part because we drink and consume pasteurized dairy products, milk and dairy products,” he says. “There definitely could be a concern if people are consuming raw, unpasteurized milk or unpasteurized products. But pasteurization inactivates this virus. The Food and Drug Administration has confirmed that this is not a real hardy virus in terms of heat and time treatments.”
Under this grant, the nine projects are funded for 12 months, with research wrapping up next spring.
9 intertwined projects
Though teams are working on nine separate research projects, Wells says many are intertwined. “A number of these are related in one way or another with transmission,” he says. “How is this virus moving around? How is it getting into dairy herds? How are these herds becoming affected?”
Wells says that in the cases of the first dairy herd detection, which were in Texas and New Mexico, the same genotype infecting cows also was found in wild birds in that area.
“So, it seemed to be a spillover from wild birds,” he says, adding that it has become known that a reservoir where the virus maintains itself is in wild aquatic ducks, particularly dabbling and diving ducks.
Minnesota’s location in the Mississippi flyway of migratory birds begs the question about whether that puts a viral bull’s-eye on the state. Erik Jopp, assistant director with the Minnesota Board of Animal Health (BAH), says that bull’s-eye may be firmly in place for poultry farm infections, but “if it’s truly that B3.13 strain is affecting the dairy, that’s not a strain that they found necessarily in the migratory waterfowl.”
The project that Wells is spearheading is looking at herd risk factors, “where we epidemiologically compare infected and noninfected herds to look for associations and what’s different.”
Wells admits that this study is not definitive, but it helps focus the research to areas that are different, similar to a study he worked on about a decade ago, when HPAI broke out in turkeys.
“We worked with a large turkey company in Minnesota and Wisconsin, and collected data from over 80 farms to figure out what are some of the ways that these herds were getting infected,” he says. “We found back then, for example, that early in the outbreak, there seemed to be different pathways of transmission to these farms compared to later in the outbreak. Or early on, it seemed to be there was an environmental component, where different farms reinfected from different strains to the environment. But later on, it was more farm-to-farm spread after a number of these farms became affected.”
Learning more of the how and why H5N1 and the various strains infect poultry flocks and make the leap to other species such as dairy and even humans are the end goals of these research projects, but as Wells admits, the more research that is completed may create more questions.
Milk sampling is important
H5N1 making the jump to dairy creates more questions on its own, and to get better tracking of the virus, the USDA initiated a National Milk Testing Strategy. The Minnesota Department of Agriculture, working with state and industry partners, under this national program began monthly bulk tank testing of raw milk during the week of Feb. 24. This testing is conducted at the UMN Veterinary Diagnostic Laboratory on the St. Paul campus.
Since the rollout of the program, more than 1,800 samples have been collected from dairy farms across the state. Samples are collected from all Minnesota producers sending their milk for processing, regardless of where their milk is shipped — even out of state.
If the H5N1 virus is detected in a milk sample, as was the case in late March from a Stearns County dairy, the BAH quarantines the herd and requires permitting of animals or animal products to move on or off the farm, except for milk, which is allowed to continue to be shipped for processing.
Though the quarantine is not voluntary, Jopp and Wells recommend that dairy producers receiving an H5N1-positive milk sample cooperate with the BAH and UMN for further research. All communication would be confidential.
“With this being a newer disease in dairy animals, we don’t know exactly how it’s affecting the animals, how it’s transmitted, how long they’re infected, some of those things,” Jopp says. “We want to try to answer some of those questions so we can better respond to these positive results. … The encouragement would be to allow the university to do some of the research on their farm, on-site, so we can learn more to help us react appropriately from what we learn. Are there instances where an animal may hold and shed this virus longer? Those are the kinds of the questions that we don’t have answers to.”
Researchers hope to find such answers, but as admitted earlier, these studies may result in more questions.