Noah McCrory
The Department of Agriculture is ordering the dairy industry to test milk-producing cows for infections caused by highly pathogenic products. bird fluor HPAI H5N1, before being transferred between states, federal officials announced Wednesday.
USDA’s decision to increase testing requirements for HPAI H5N1 comes after the Food and Drug Administration released Tuesday that samples of pasteurized milk that were sold on supermarket shelves tested positive for the virus, prompting further research to see whether the positive test was caused by lingering dead “virus particles” or live infectious viruses.
It also comes after federal authorities said they detected some “isolated” but concerning changes in the virus in cows, which U.S. officials believe contracted the virus from wild birds.
Veterinarians and state laboratories that find cattle test positive for the virus will be required to report their results to the USDA. Farms with sick cows will need to undergo investigations before moving cattle across state lines.
“The main focus of orderInitially, these will be lactating cattle. But we certainly will have the opportunity to expand beyond that as needed,” Mike Watson, head of the USDA’s Animal and Plant Health Inspection Service, told reporters Wednesday.
“We must be very clear that the tests that came back positive are for the genetic material of the virus. They could just be fragments of the virus, what remains after pasteurization. And that in itself is not a cause for alarm,” said Dr. Céline Gounder, medical contributor for CBS News and public health editor at large for KFF Health News. “There are additional tests being done to see if this infectious virus is alive or if it is just the dead virus that we would expect to see.”
If it’s just leftovers from the pasteurization process, “you shouldn’t get sick,” Gounder added.
Employees said previously that the unprecedented spread of the virus among dairy cattle likely traces back to a single wild bird spread event, based on an analysis of genetic sequences collected from sick cattle.
Since then, genetic data and investigations suggest that the virus has spread and infected cows around the world. at least eight states it is a human dairy worker in Texas. Egg farms in Texas and Michigan are also suspected of being infected by viruses that spread from cows, increasing millions of birds culled due to wild bird infections.
“These farms are close to the affected dairy farms. And so there could be a lateral flow from the dairy farms to these poultry operations, to these egg laying operations. This could be things like the transfer of the virus through fomites, as in clothing or in vehicles,” said Jamie Jonker, scientific director of the National Dairy Federation, in a recent Swine Health Information Center webinar.
The virus was not initially found in the respiratory tracts of most infected cows, officials said, suggesting it is not spreading through the air among cows like other types of flu. Instead, HPAI H5N1 in the current outbreak was found almost exclusively in raw milk and the cow’s organs that produce it. Authorities believe the virus may have spread among cows during the milking process on farms, through surfaces contaminated with infected raw milk.
However, Watson said at least one cow destined for slaughter was found with signs of the virus in its lung tissue. The cow was condemned by USDA inspectors and did not enter the food supply, Watson said.
Federal scientists also found a mutation in another sick Kansas cow that had a genetic change that adapted the flu to spread better in mammals.
“The only sequence change and the only dairy cow with H5N1 in lung tissue so far appear to be isolated events. However, the new movement of H5N1 between wild birds and dairy cows requires further testing,” Watson said.
Most cows have recovered from the virus without dying, Watson said. This contrasts sharply with the type of mass deaths seen in birds and some other species. However, dairy industry officials have previously said that some cows have not yet recovered their ability to produce milk, raising concerns about long-term problems for some cattle.
“We need time to develop an understanding that supports any future actions. Therefore, this federal order is critical to increasing the information available to USDA,” Watson said.
H5N1 HPAI virus found in pasteurized milk
Although health officials say they believe previous work pasteurizing eggs for HPAI H5N1 and milk for other germs suggests the process will be sufficient to eradicate the danger of any lingering traces of the virus found in milk, they say studies are also underway to Check that pasteurized milk remains safe.
“A positive PCR test does not necessarily mean that the sample contains an intact infectious pathogen and that additional testing is needed to determine whether the intact pathogen is still present and whether it remains infectious,” said Don Prater, chief of the FDA’s Center for Food Safety. at the press conference.
This involves what the FDA says is the “gold standard” for checking whether the virus they find is potentially infectious, taking the H5N1 HPAI particles they find and checking whether it will grow in chicken eggs.
Research supported by the National Institutes of Health also found fragments of HPAI H5N1 in milk. Early testing of these samples suggests that the virus in pasteurized milk was not infectious, trying to grow the virus in chicken cells and eggs.
“While this is welcome news, the effort studied a small number of samples that is not necessarily representative of all milk sold at retail. So to really understand the scope here, we need to wait for the FDA,” said the National Institute of Allergy and Infectious Diseases. Director Dr. Jeanne Marrazzo.
Prater said the samples came from a national survey of the U.S. milk supply, but declined to share details about where they were found and which types of milk tested positive.
“We don’t have information to share yet, but it will be released very soon and that’s what I can share at this time,” Prater said.
Milk from cows known to have symptoms of the virus is not entering the supply chain, Prater said. But it’s possible the virus is getting into the supply chain from other sources, Prater said, possibly from cows that aren’t yet symptomatic or have previously recovered.
The FDA has some data that could help investigators track where milk with the virus got into the food supply, Prater said.
“At this point we will be able to analyze the information we are collecting as part of this. Our traceability information is good, but it’s not perfect,” Prater said.
