A mysterious illness affecting older dairy cows in the southern U.S. appears to be caused by the same virus that has infected millions of domestic and wild birds over the past few years.
On Monday, the U.S. Department of Agriculture said milk samples from sick animals on two dairy farms in Kansas and one in Texas, as well as a throat swab from a farm in Texas, tested positive for highly pathogenic avian influenza (HPAI).
Federal and state officials have been investigating multiple cases in Texas, Kansas, and New Mexico where cows have been experiencing decreased lactation, low appetite, and other symptoms.
The virus appears to have been introduced by wild birds. Genomic sequencing is underway to better understand the situation, the department said in a news release on Monday.
There is no concern about food safety, noted U.S. dairy, beef, and meat industry groups. Milk from sick animals is not supposed to enter the food supply, and pasteurization inactivates influenza viruses.
For the dairies whose herds are exhibiting symptoms, about ten percent of each affected herd appears to be impacted, with little to no mortality among the sick animals, says the USDA.
Last week, a deceased young goat on a farm in Minnesota where a poultry flock was infected with HPAI tested positive for the same virus — the first confirmed finding in a domestic ruminant in the U.S.
The farm owner in Stevens County, Minnesota noticed unusual deaths of newly-kidded goats in early March on the property where a backyard poultry flock was depopulated due to HPAI in February.
“This finding is significant because, while the spring migration is definitely a higher risk transmission period for poultry, it highlights the possibility of the virus infecting other animals on farms with multiple species,” said Minnesota’s State Veterinarian, Dr. Brian Hoefs. “Thankfully, research to-date has shown mammals appear to be dead-end hosts, which means they’re unlikely to spread HPAI further.”
The avian influenza virus has previously been found in other mammals, such as skunks, dogs, and cats. Animals with weakened or immature immune systems are at higher risk of contracting the virus.
North of the border, while the spring migratory season has begun, the Canadian Food Inspection Agency has not reported any new on-farm cases of HPAI since February, when it was confirmed on farms in Alberta and Quebec.
