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U.S. Department of Agriculture detects second bird flu strain in dairy cattle

U.S. dairy cattle tested positive for a strain of bird flu that previously had not been seen in cows, the U.S. Department of Agriculture said on Wednesday, ramping up concerns about the persistent spread of the virus.

The H5N1 virus has reduced milk output in cattle, pushed up egg prices by wiping out millions of hens, and infected nearly 70 people since April as it has spread across the country.

Genome sequencing of milk from Nevada identified the different strain, known as the D1.1 genotype, in dairy cows for the first time, the USDA said. Previously, all 957 bird flu infections among dairy herds reported since last March had been caused by another strain, the B3.13 genotype, according to the agency.

Reuters reported news of the detection of the second strain on Wednesday ahead of USDA’s announcement.

The second strain was the predominant genotype among wild birds this past fall and winter and has also been found in poultry, the USDA said. It was identified in dairy cattle through an agency program that began testing milk for bird flu in December.

“We’re seeing the H5N1 virus itself be smarter than all of us,” said Beth Thompson, South Dakota’s state veterinarian.

“It’s modifying itself so it’s not just staying in the poultry and the wild waterfowl. It’s picking up a home in the mammals.”

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What It Takes to Stop African Swine Fever - Dr. Jishu Shi

Video: What It Takes to Stop African Swine Fever - Dr. Jishu Shi



In this episode of The Swine it Podcast Show Canada, Dr. Jishu Shi, Professor of Vaccine Immunology at Kansas State University, discusses African swine fever prevention and vaccine development. He explains why ASF differs from classical swine fever and swine influenza, how the disease threatens trade and pork production, why immunization safety remains a critical hurdle, and what producers can do now to reduce the risk of introduction. Listen now on all major platforms!

"Before a safe and efficacious vaccine for ASF can be commercialized, what we really have is prevention."

Meet the guest: Dr. Jishu Shi is Professor of Vaccine Immunology and the Dr. Wayne & Hilda Appleton Endowed Professor at Kansas State University’s College of Veterinary Medicine. He directs the Center on Biologics Development and Evaluation and the U.S.-China Center for Animal Health. A veterinarian and vaccine immunologist, Dr. Shi has focused on vaccines for pigs and has worked on African swine fever vaccine development, control, diagnostics, and international training since 2018. Learn more from Dr. Jishu Shi on The Swine it Podcast Show Canada, available on all major platforms.