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By Mandy Taheri
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The U.S. Department of Agriculture (USDA) on Wednesday confirmed the detection of avian influenza in dairy cattle in Nevada, marking the second strain found in cows since last March.
Newsweek has reached out to the USDA for comment via email on Wednesday.
Why It Matters
Bird flu across the U.S. has impacted hundreds of millions of poultry and has spread to mammalian species, including dairy cows and dozens of people.
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The virus's second jump to cows raises concerns about its ability to mutate and its growing impact on health and the economy, especially amid an egg shortage.
What To Know
Dairy cows in Nevada have been infected with bird flu, the USDA's Animal and Plant Health Inspection Service National Veterinary Services Laboratories announced in a statement on Wednesday.
After conducting a "whole genome sequence" on a selection of Nevada dairy cows, the USDA concluded that the animals had a new strain of bird flu which had not previously been reported in cows, H5N1 clade 2.3.4.4b, genotype D1. This has been the predominant bird flu genotype across the U.S., which has mostly been identified in wild birds and poultry during the fall and winter.
This is not the first time bird flu has impacted dairy cows, having infected 957 herds across 16 states since last March. However, all those cows were sick from a different strand, the B3.13 genotype, the USDA said. This marks the first time the cows are sick with the same dominant circulating strain.
The strain has also sickened 67 people and caused one death. Since the outbreak began in 2022, all 50 states have reported infections and hundreds of million birds have been affected.
The identification of the new strain came after state tracing and initial testing under the USDA's National Milk Testing Strategy, which came out of a December order in order to help monitor the spread of bird flu in dairy cows.
Bird flu has had lasting impacts on prices and availability of eggs across the U.S., and with more cows impacted by the virus, other dairy products may be impacted.
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What People Are Saying
Richard Webby, an influenza expert at St. Jude Children's Research Hospital, told the New York Times on Wednesday: "I was kind of under the belief that the bird-to-cow movement was a pretty rare event," and the fact that it has happened again is "a little bit of a 'wow' to me."
Angela Rasmussen, a virologist, wrote on X, formerly Twitter, on Wednesday: "New development: this is the first detection of genotype D1.1 H5N1 virus in cattle. All cattle sequences to date were genotype B3.13 & were all descended from a single spillover. New genotype means new introduction to cows from birds."
Dr. Ian Weissman, a radiologist wrote on X on Wednesday: "USDA milk testing shows different strain of H5N1 #birdflu in Nevada dairy herds. Not previously detected in cows, the strain has circulated in wild birds and led to a fatal infection in a person in Louisiana last month."
What Happens Next
The USDA announced that "in the interest of sharing information of import to the scientific community," the agency will post the sequence data and technical findings in the coming weeks.
The Centers for Disease Control and Prevention (CDC) continues its surveillance efforts and is working with states to monitor individuals exposed to infected animals but maintains that the "current public health risk is low."
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