USDA Now Requiring Mandatory Testing and Reporting of HPAI in Dairy Cattle as New Data Suggests Virus Outbreak is More Widespread
USDA is now ordering all dairy cattle must be tested prior to moving the animals across state lines as a way to help stop the spread of HPAI H5N1 impacting dairy herds across the country. This comes after a lab at Ohio State University detected genetic material of the virus in 38% of retail milk samples they’ve tested, data that also suggests the current outbreak is being underreported.
In a new Federal Order announced on Tuesday, USDA says in an effort to protect the U.S. livestock industry from the threat posed by highly pathogenic H5N1 avian influenza, there are a number of actions being taken with federal partners to limit the spread.
The following measures go into effect immediately:
- Prior to interstate movement, dairy cattle are required to receive a negative test for the Influenza A virus at an approved National Animal Health Laboratory Network (NAHLN) laboratory.
- Owners of herds in which dairy cattle test positive for interstate movement will be required to provide epidemiological information, including animal movement tracing.
- Dairy cattle moving interstate must adhere to conditions specified by APHIS.
USDA says forthcoming guidance will be released, but these steps will be immediately required for lactating dairy cattle, while these requirements for other classes of dairy cattle will be based on scientific factors concerning the virus and its evolving risk profile.
USDA is also requiring labs and state veterinarian offices to start mandatory reporting of Influenza A nucleic acid detection diagnostic results, which is PCR or genetic sequencing, in livestock. That must be reported to USDA APHIS.
Prior to Tuesday's announcement, HPAI H5N1 in livestock was not currently a reportable disease.
“It's not a foreign animal disease in dairy, like it's considered in poultry -- same virus -- but in poultry, there are reporting requirements. This is considered an emerging disease (in dairy cattle). And with that, there are no reporting requirements,” one source told Farm Journal.
USDA also says while the virus is spreading between cows in the same herd, from cows to poultry, as well as spread between dairies associated with cattle movements, now some cows that don't signs of the illness are still testing positive for the virus. One sample came from a cow in Kansas. USDA says on April 16, APHIS microbiologists identified a shift in an H5N1 sample that could indicate that the virus has an adaptation to mammals.
"While we are taking this action today, it is important to remember that thus far, we have not found changes to the virus that would make it more transmissible to humans and between people," states USDA. "While cases among humans in direct contact with infected animals are possible, our partners at the U.S. Centers for Disease Control and Prevention (CDC) believe that the current risk to the public remains low.
Genetic Material of the Virus Detected in Retail Milk
On Tuesday, the FDA reassured consumers the pasteurized milk they drink is safe after the agency announced retail milk samples tested positive for fragments of HPAI H5N1. Further testing showed the virus is not live, which means there is no risk to human health. However, researchers say this does indicate avian influenza in the nation’s dairy herd is much more widespread than what’s currently being reported and USDA's decision to stop the movement of cattle also confirms how quickly the virus is spreading.
In an update from the FDA, the agency said it tested milk samples by polymerase chain reaction (PCR) and found the presence of fragments of the virus, which is not the same as infectious virus and currently poses no increased risk to human health.
Dr. Andrew Bowman, an associate professor in the College of Veterinary Medicine at The Ohio State University, is part of a lab that has focused largely on zoonotic transmission of influenza for decades. Historically, his research has worked on avian species and swine, but when the detection of influenza and cattle was announced, they started shifting gears and looked at cattle, especially considering there are no cattle influenza experts since it's not a species that anyone really had on the list for influenza, nor was avian influenza in cattle a possibility that researchers were exploring.
Virus Material Found in 38% of Retail Milk Samples at Lab
The Ohio State lab is part of the National Institutes of Health (NIH) network for the Centers for Excellence in Influenza Research and Response. As the team worked together to generate scientific data, Bowman and the team needed to try to get a handle on the scope of the new outbreak of HPAI H5N1 in cattle. They decided it would be quicker and more efficient to test samples of retail milk versus visiting every dairy farm in the country.
“We've tested 150 samples, 58 of those have tested positive to date,” says Bowman. “We've screened them for the presence of influenza genetic material, so the viral RNA. Those that have tested positive, we have been forwarded to St. Jude Children's Research Hospital, where they are conducting studies to see if there's a viable virus in there. To date, none of them have been viable, but certainly they give the indication that there is viral genetic material in the region.”
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Bowman says the team purchased milk from six different states, and the processing plant codes on those 58 positives represent 10 different states where the milk was processed.
“I think this certainly gives us some idea that it's a larger problem than the handful of states in the 38 farms that had been reported,” says Bowman. “I think it's much more common.”
The difference between finding viral RNA, which is genetic material, versus a live virus, is a major point in reassuring consumers the U.S. milk supply is safe, but it’s also a key metric in tracking how widespread the virus actually is.
“Just like if we find DNA at a crime scene, it shows somebody was there. But it's not saying they're there and active right now,” says Bowman. “We can piece that together and know that there was evidence that the virus was in the milk, but it's been rendered inactive, likely by pasteurization.”
Bowman says viral RNA, which is what his lab detected in retail milk, does not cause humans to get sick.
“In fact, if we look for other pathogens, RNA and DNA, we probably find some of that as well. But we are using it as an indication of how widespread influence is in the US dairy cattle herd,” says Bowman.
APHIS continues to track the number of cases nationwide, and the latest look at confirmed cases of HPAI in domestic livestock shows 26 cases in 8 states. However, additional veterinary professionals have spoken to Farm Journal and said APHIS’ numbers aren’t accurate with what’s actually happen in the countryside and the virus is more widespread than what’s being reported.
U.S. Milk Supply is Still Safe
While the number of cases- and scope of the virus in the U.S. cattle herd- is currently under question, Bowman says their research indicates the U.S. milk supply is safe.
“At this point in time, there's evidence that they are viral particles entering the milk supply, but those are not viable at this point in time, and we believe pasteurization is effective. All data supports that pasteurization is effective,” says Bowman. “It's one of those cases where it's a very limited sampling at this point. And we're working hard to expand that to provide some assurance that this is the correct position to take.”
FDA confirmed again on Thursday that even though genetic material was detected in retail milk, pasteurization of milk destroys harmful pathogenic bacteria and other microorganisms, including HPAI and other viruses.
“The data cited by FDA is consistent with many other studies demonstrating that the legally required temperature and time for milk pasteurization will readily inactivate HPAI,” National Milk Producers Federation (NMPF) said in a statement. “Viral fragments detected after pasteurization are nothing more than evidence that the virus is dead; they have zero impact on human health. Further, the federal PMO prohibits milk from sick cows from entering the food supply chain. Milk and milk products produced and processed in the United States are among the safest in the world.”
The Centers for Disease Control (CDC) also reached out to Farm Journal to reaffirm the risk to human health remains low. A CDC senior official told Farm Journal CDC regularly scans emergency rooms and care systems for unusual illnesses, including flu-like symptoms, and the agency is seeing nothing usual with respect to flu activity. The CDC says the overall assessment is the risk to human health remains low.
The Biggest Unknown: How the Virus is Spreading Among Livestock
As researchers try to get a grasp on the scope, the biggest question remains how this virus continues to spread. Bowman’s lab has worked with influenza viruses for more than a decade, and he says influenza is difficult to address.
“Some of it is influenza, the virus itself because it's a segmented RNA and has a different genome. It behaves differently than some viruses, it can mix and match and reassort. So that's, that's one challenge,” says Bowman. “In this case, we're in a new species and we're all having to quickly learn all the intricacies of, of cattle production and, and how we might be transmitting. And then we add into the fact that we've seen it in pigs and birds, and it's not always a clinical presentation, they don't always show signs of disease.”
Bowman says animals that are infected may be asymptomatic, so they could be a vehicle moving the virus.
“That's certainly complicated, complicates understanding that the transmission dynamics and the ecology and epidemiology of influenza in any species, but especially in this case, it's a new species that we're really having to wrap our heads around,” says Bowman.
Bowman points out that with influenza, it’s always a question of who’s giving it to whom. His lab, along with others, are trying to piece that together, but their insights are only as good as the data that’s available. At this point in time, that data is limited. Bowman says as more data is collected, they’ll have a much stronger position to figure out what is happening.
