Less than a week after California health officials confirmed the discovery of the bird flu virus in store-bought raw milk, state agriculture officials descended on Mark McAfee’s raw milk “as before” Wednesday and began collecting samples from two farm cows, a creamery, a bulk milk tank and a truck. , according to the owner.
The visit is a recall of Raw Milk products, and also comes amid a growing H5N1 bird flu outbreak on the country’s dairy farms. Raw Farm maintains 1,800 head of cattle spread over two herds — one in Fresno, the other outside Hanford, according to McAfee. The company also has Fowler-based creams.
“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 on Wednesday, some health experts raised questions and concerns about the new positive test results.
Last week, public health officials in Santa Clara County detected the bird flu virus in a sample of McAfee’s raw milk purchased at the store. Two days later, the California Department of Public Health confirmed the findings.
But when state agriculture officials tested cows at McAfee’s dairy farm on Monday, they failed to detect the virus.
The fact that no animals have been reported to be infected with the virus has public health experts confused and concerned. Generally, once the virus appears on the farm, it spreads and doesn’t just disappear.
“The fact that all the additional tests were negative is very troubling to me,” John Korslund, a retired U.S. Department of Agriculture veterinary epidemiologist, said in an email.
Officials from the CDFA could not be reached for comment Wednesday, but an infectious disease expert told The Times that officials may review testing procedures, as well as the origin of the milk sampled.
According to test records, early samples of store-bought raw milk carried high levels of the virus, and were found to have a polymerase chain reaction cycle threshold – or Ct – of about 25.
“A herd should not be immediately negative after reading 25 if it is milk from the same herd, IMO,” Korslund wrote in an email.
Richard Webby, director of the World Health Organization’s Collaborating Center for the Study of the Ecology of Influenza in Animals and Birds, and a researcher in the Department of Infectious Diseases at the Children’s Research Hospital of St. Jude in Memphis, Tenn., agrees.
“Okay, it’s not a weak positive … and it’s definitely not on the borderline where some tests will be positive and others will be negative,” he said after reviewing the test notes.
Webby, Korslund and other experts say the test they use only looks for the H5 part of the H5N1 virus, and can’t tell if the virus is inactive or alive. A second test – called a virus isolation test – must be performed to confirm that the sample is H5N1 and active.
State and federal health officials say the H5N1 bird flu virus poses little risk to the public. However, he urged people to avoid drinking unpasteurized raw milk. No outbreaks have been reported in consumers linked to avian flu in contaminated raw milk.
Bottled milk on November 9. Raw Farm LLC recalled all products associated with positive samples. McAfee estimates the recall involves about 2,000 gallons of half-gallon and quarter-gallon “top cream” dairy products.
Since the start of the outbreak, 461 herds have been infected in California — including herds in Fresno and Kings County, where McAfee’s herd is located.
At the start of the H5N1 milk outbreak, federal health officials tested samples of pasteurized milk and found the virus in 20% of samples collected from retail shelves. However, when further tests were carried out – isolation of the virus – they were able to show that it was an inactive virus that had been denatured by heat.
So why would a raw milk sample test for the virus and the dairy herd not be positive?
Korslund admits that testing and sampling can sometimes be compromised, but he doesn’t tend to doubt the testing. He said the Ct value — and the lack of subsequent positive tests — indicated “a product integrity issue rather than a herd infection.”
“What if somewhere in the bottling process, pasteurized shelf milk is added to raw milk to meet the demand for insufficient supply? In such a scenario, we don’t have a testing problem; rather, a product integrity problem that usually goes undetected,” he said.
That’s why virus isolation tests are critical, Korslund said. This will help determine whether the virus in the collected sample is still alive or not.
A spokesman for the country’s health department said the sample tests had been completed. He did not say that the isolation of the virus had been completed, but noted that the positive results had been confirmed by state and now federal laboratories.
McAfee said he doesn’t think the virus is in his herd. Tests conducted by the state agriculture department – twice a week – on the milk were mostly negative. In addition, he noted, tests conducted on Monday also did not show the virus.
In addition, he said, he monitors each cow in the farms with a high-tech device – made by the Austrian company smaXtec – which sits on the cow’s udder and sends real-time information about the animal’s body temperature, milk acidity, etc.
He said there was no indication that the virus passed through the herd based on the data.
He also said that all the equipment – from trucks, to bulk tanks and bottling plants – was closed on the farm and the dairy was outside; they are used only by Raw Farm, LLC.
He said he worries state officials are determined to “find something.”
