USDA Confirms New Strain of Avian Flu in Dairy Cattle

By Erin Jester

The USDA announced on Wednesday that the predominant genotype of avian flu circulating in migratory birds, called D1.1, was responsible for an outbreak at a dairy farm in Nevada – the first time the strain has been detected in dairy cattle.

All previous dairy farm outbreaks were caused by the B3.13 genotype of highly pathogenic H5N1 avian flu, said Benjamin Anderson, Ph.D., an assistant professor in the University of Florida College of Public Health and Health Professions’ Department of Environmental and Global Health and lead for UF’s Emerging Pathogens Institute bird flu response team.

The D1.1 genotype is the same strain that killed a Louisiana resident in January and sent a Canadian teenager to an intensive care unit in November. The D1.1 genotype to date has also been responsible for most poultry outbreaks across the US. 

“This represents a concerning event if D1.1 continues to show up in dairy farms as well,” Anderson said.

No cases of H5N1 have been detected in Alachua County. The most recent avian flu outbreak in Florida was associated with a backyard poultry operation in Broward County, detected on Jan. 30. 

The Centers for Disease Control and Prevention says the risk to public health is still low, and is using its flu surveillance systems to monitor bird flu activity in people. 

Recently, bird flu has had a substantial impact on egg production. If avian flu is detected in one chicken on a farm, the entire flock must be euthanized to prevent spread. This has led to the death of millions of poultry in the most recent outbreak, dropping the nation’s egg supply and causing the price of eggs to soar.

Although the local risk of contracting avian flu is low, Anderson warned against consuming raw milk, which has been associated to human and animal H5N1 infections and carries a risk of salmonella. Reports of H5N1-infected raw pet food, too, have led to some feline casualties. 

In response to H5N1 cases in cats due to raw food, the U.S. Food and Drug Administration announced in January it will now require cat and dog food manufacturers to update their safety plans to protect against the virus.