Milk cows in Texas and Kansas have tested positive for bird flu in a development labelled “highly concerning” by an expert.
The US Department of Agriculture (USDA) said it was investigating an illness among primarily older dairy cows in Texas, Kansas, and New Mexico that farmers had dubbed “mystery cow disease”.
The illness had caused decreased lactation, low appetite and other symptoms.
As of Monday, milk collected from sick cows from two dairy farms in Kansas and one in Texas, tested positive for avian influenza.
In a statement, USDA said based on findings from Texas, the infections appeared to have been introduced by wild birds also found at the farms, and that initial tests did not suggest a higher risk to the public.
“For the dairies whose herds are exhibiting symptoms, on average about ten percent of each affected herd appears to be impacted, with little to no associated mortality reported among the animals,” said the department in a statement.
“Milk loss resulting from symptomatic cattle to date is too limited to have a major impact on supply and there should be no impact on the price of milk or other dairy products.”
Gregory Gray, an epidemiologist at the University of Texas, said the new detections in cows across multiple states was a “worrisome” development because it may signal the bird flu strain could be transmitting between cattle.
He told the Science website: “It’s worrisome. We most recently saw the infections in goats, and we’ve all seen the wildlife being affected with the hotter pathogenic avian flu, including the strange infection of carnivores—bears and wolves.
“Who knows what’s next? It’s disturbing. We need to figure this thing out, because if the virus continues to change, it could move into other species, including humans.”
However, federal officials stressed there was “no concern” of greater risk to consumer health, and that the situation was being closely monitored.
Officials said milk from impacted animals is being diverted or destroyed so that it does not enter the food supply and that pasteurisation has been proven to inactivate bacteria and viruses, like influenza, in milk.
Dairy farmers in Texas first raised the alarm three weeks ago when cattle started falling ill with “mystery dairy cow disease," Texas Department of Agriculture Commissioner Sid Miller said.
He said that milk production fell sharply in affected cows and that they were lethargic and weren't eating much.
“We hadn't seen anything like it before,” he said. “It was kind of like they had a cold.”
The strain, type A H5N1 strain, has been known for decades to cause outbreaks in birds and to occasionally infect people.
