GFB News Magazine
Avian flu found in dairy cattle
by Jennifer Whittaker
GFB Publications Editor
Posted on May 30, 2024 12:24 PM
By Jennifer Whittaker
Until this spring, U.S. farmers had only experienced Highly Pathogenic Avian Influenza (HPAI), commonly called avian flu, infecting poultry flocks.
Then, on March 20, the H5N1 strain of avian flu was found in goat kids in Minnesota on a small farm where they shared a water source with backyard poultry that tested H5N1 positive in February. From March 25 to June 5, cattle at more than 80 dairy farms in nine states tested positive for H5N1. As of May 28, the virus had not been found in a Georgia dairy herd.
As of June 5, three people had tested positive for H5N1 related to cases of the virus in dairy cattle. In April, the CDC reported a person in Texas exposed to infected cattle reported eye redness (consistent with pink eye), as their only symptom. A Michigan dairy worker was announced positive May 22 also presenting eye redness. A second Michigan dairy worker was confirmed to have avian flu on May 30; this worker experienced respiratory symptoms and was recovering after taking antiviral medication.
H5N1 in dairy cattle
According to the American Veterinary Medical Association, this is the first time avian flu has been found in dairy cattle.
Cows infected with HPAI are exhibiting symptoms including: decrease in milk production (10-30 lbs./cow), low appetite and fever, the USDA reports.
USDA has confirmed H5N1 detections in dairy herds in: Texas, Kansas, Michigan, Idaho, New Mexico, Ohio, North Carolina, South Dakota and Colorado. As of May 24, Texas, Kansas, Michigan, New Mexico, Idaho, Colorado and South Dakota had multiple dairy herds test H5N1 positive.
Wild migratory birds are believed to be the source of avian flu infections in the herds in Texas, Kansas and New Mexico. USDA or state officials in four states - North Carolina, Michigan, Idaho and Ohio – reported the initial dairy herds infected with H5N1 in these states acquired cows from infected Texas dairy herds before the Texas herds tested positive.
USDA believes there is cow-to-cow transmission. One possible way the virus may be spreading between lactating cows is via milking equipment. A cow’s udder is cleaned and disinfected before the milking machine is attached, but milk droplets from an infected cow in the suction cups could be passed to the next cow.
USDA estimates about 10% of the cattle in the infected herds are symptomatic. Most have recovered within two weeks with little to no deaths, the USDA says. Due to this low infection rate and because the cows recover, dairy herds are not being depopulated. Unlike dairy cows, poultry flocks have a high mortality rate when infected with avian flu.
Since the start of the 2022 HPAI H5N1 outbreak, the USDA has confirmed more than 200 detections of HPAI in wild mammals nationwide https://gfb.ag/usdahpaimammals.
Dairy cattle must be tested to move interstate or be part of the herd status pilot program
The USDA issued a federal order effective April 29 requiring that all lactating dairy cattle test negative for H5N1 avian influenza before being moved across state lines.
Then on June 3, the USDA launched a Voluntary H5N1 Dairy Herd Status Pilot Program. Dairy producers from states enrolled in the first phase of this program who choose to enroll their herds and whose herds test negative for H5N1 for three consecutive weeks using on-farm bulk tank milk samples or similar representative milk samples tested at a NAHLN laboratory will be able to move animals without additional pre-movement testing of individual cattle currently required under the federal order issued April 29. Producers must also comply with continued regular weekly monitoring and testing of the herd for H5N1.
Under the April 29 federal order, Georgia producers needing to move lactating dairy cattle out of state should contact the Georgia Department of Agriculture (GDA) at 404-656-3667. Samples of milk must be collected, and negative test results obtained at least seven days before moving cattle. A cow testing positive for HPAI, must wait 30 days before being retested.
USDA requires all samples to be collected by a licensed veterinarian or someone the GDA approves. Dairy producers are encouraged to contact Georgia Milk Producers Executive Director Bryce Trotter at 229-221-3906 or GDA if they don’t have a vet who can pull samples.
USDA will reimburse producers for all premovement testing at approved laboratories. It is not reimbursing for collecting or shipping samples. Owners of cattle cleared for interstate movement must provide epidemiological information, including animal movement tracing.
Lactating dairy cows may be moved from a farm to a sale barn in the same state without being tested. Subsequent interstate movement of a lactating dairy cow from a sale barn directly to a slaughter facility requires only a Certificate of Veterinary Inspection (CVI) stating the animal is clinically healthy. Lactating dairy cows showing no signs of H5N1 may move across state lines directly to slaughter if they have a CVI or other document the state veterinarians in both the sending and receiving state approve.
USDA recommends all animals moved on/off a premise be isolated for 30 days to prevent the spread of disease.
Visit www.gfb.ag/usdah5n1dairytestinfo and www.gfb.ag/usdaclarifiestestingorder for complete details.
Pasteurized dairy products safe to eat
On April 26, the U.S. Food & Drug Administration (FDA) said tests it did on pasteurized milk taken from store shelves in 38 states show pasteurization is effective in killing the strain of H5N1 found in dairy cows and that pasteurized U.S. milk and dairy products are safe for human consumption.
FDA also tested samples of retail powdered infant formula and toddler formula. The FDA reports all results of formula testing were H5N1 negative.
FDA, Centers for Disease Control (CDC) and the USDA maintain that consuming pasteurized dairy products is the safest way to assure dairy products are safe to consume.
H5N1 has not been found in ground beef
On May 1, USDA announced that H5N1 has not been found in any of the samples of ground beef from across the U.S. that it tested. USDA collected samples of ground beef from retail stores in each of the nine states with dairy herds that tested positive for H5N1 at the time the samples were collected.
To verify the safety of the U.S. meat supply from H5N1, USDA is working on two separate beef safety studies related to avian flu in meat from dairy cattle.
On May 24, the USDA announced that H5N1 viral particles had been found in muscle tissue samples from one of 96 dairy cattle tested at slaughter facilities inspected by the USDA Food Safety and Inspection Service (FSIS). These 96 cows had been condemned to die and did not enter the food supply chain because they had a systemic disease. USDA is working to trace the cow back to its farm of origin to gather further information.
FSIS personnel identified signs of illness in the positive cow during post-mortem inspection and prevented the animal from entering the food supply as part of routine FSIS operations. USDA says this should provide confidence that the food safety system the U.S. has in place is working.
Meat and eggs from poultry farms confirmed to have avian flu are destroyed before entering the food supply.
Visit www.gfb.ag/usdaavianfluinfo for USDA updates & biosecurity resources.