Less than a week after California health officials confirmed that store-bought raw milk contained the bird flu virus, state agriculture officials descended on Mark McAfee’s Raw Farm dairy “as never before” Wednesday and began collecting samples from the farm’s two herds, the creameries. Bulk milk tanks and trucks, by owner.
The visit follows the recall of raw farm products and comes amid a series of outbreaks of H5N1 bird flu in the state’s dairy farms. Raw Ranch maintains 1,800 head of cattle in two herds — one in Fresno, the other outside Hanford, according to McAfee. The company also has a Fowler-based creamery.
“I think they’re in full attack mode,” he said, describing the search in detail. In addition to milk, Raw Farm produces cheese and kefir.
As California Department of Food and Agriculture officials collected samples and conducted tests at the dairy farm on Wednesday, some health experts raised questions and concerns about the latest positive test results.
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Last week, public health officials in Santa Clara County detected the bird flu virus in a sample purchased at McAfee’s Raw Milk Store. Two days later, the California Department of Public Health confirmed the finding.
But when state agriculture officials tested cows at McAfee’s dairy on Monday, they failed to detect the virus.
The fact that no animals have been infected with the virus has puzzled and worried public health experts. Generally, once a virus appears on a farm, it spreads and does not go away.
“It really bothers me that all the supplemental tests are negative,” John Korslund, a retired U.S. Department of Agriculture veterinary epidemiologist, said in an email.
CDFA officials could not be reached for comment Wednesday, but infectious disease experts told the Times that officials are reviewing testing procedures and the actual appearance of the sampled milk.
An initial sample of store-bought raw milk carried high levels of the virus, and the polymerase chain reaction cycle limit — or Ct — was found to be approximately 25, according to test records.
“After reading a herd 25, if it is indeed milk from the same herd, IMO it shouldn’t be immediately negative,” Korslund wrote in an email.
Richard Webby, director of the World Health Organization’s Collaborating Center for Studies on the Ecology of Influenza in Animals and Birds and a researcher in the Department of Infectious Diseases at St. Jude’s Children’s Research Hospital in Memphis, Tenn., agreed.
“Well, it’s not a weak positive … and certainly not on the borderline where some tests are positive and others are negative,” he said after reviewing the test records.
Webby, Korslund and other experts note that the test used only looks for the H5 region of the H5N1 virus and cannot determine whether the virus is inactive or alive. The second test – a virus isolation test – is to confirm that the sample is H5N1 and that it is active.
Read More: A warning has been issued about contaminated milk being sold in LA County stores
State and federal health officials say the H5N1 bird flu virus poses a low risk to the public. However, they urged people not to drink raw, unprocessed milk. There have been no outbreaks in consumers associated with avian influenza in contaminated raw milk.
The milk was bottled on November 9. Raw Farm LLC has recalled all products associated with the positive sample. McAfee estimates the recall of about 2,000 gallons of half- and quarter-gallon “cream top” whole milk products.
Since the outbreak began, 461 herds have been affected in California — including herds in Fresno and Kings County, where McAfee’s herds are located.
Early in the H5N1 milk outbreak, federal health officials tested pasteurized milk samples and Virus was detected in 20% of the samples Collected from retail shelves. However, when further testing was carried out – virus isolation – they were able to show that the heat-deactivated virus was inactivated.
So why would a raw milk sample test positive for the virus and a dairy herd not test positive?
Korslund acknowledged that testing and models can sometimes be compromised, but in this instance he didn’t want to doubt the tests. He said the Ct value — and the lack of subsequent positive tests — suggested a “product integrity issue rather than a herd infection.”
“What if somewhere in the bottling process, pasteurized shelf milk is spiked with raw milk to meet enough supply requirements? In that case, we don’t have a test issue; rather it’s a product integrity issue, which is usually undetectable,” he said.
This is why virus isolation testing is important, Korslund said. This helps to determine whether the virus in the collected sample is alive or not.
A spokesman for the state health department said testing of the sample had been completed. He did not say whether the isolation of the virus had been completed, but noted that the positive result had been confirmed by state and now central laboratories.
McAfee said he doesn’t think the virus is present in his herd. Regular tests by the state’s Department of Agriculture — twice a week — were negative on her whole milk. Additionally, he noted, a test taken on Monday also did not contain the virus.
In addition, he monitors each cow on his farms with a high-tech device – Austrian company smaXtec – which sits on a cow’s lap and transmits real-time information about the animal’s body temperature, milk acidity, etc.
Based on that data, he said, there are no signs of the virus spreading through his herd.
He owns all of his equipment — from his trucks, to his bulk tanks and bottling plant — to outlying farms and dairy; They are used only by Raw Farm, LLC.
He said he was concerned that state officials were determined to “find something.”
This story appeared first Los Angeles Times.
