Bird Flu Continues to Spread, Infecting Poultry and Dairy Cattle

Jun 11, 2025

By Caroline Long

The current strain of highly pathogenic avian influenza first hit the United States in January 2022. By April that year, it had been confirmed in both domestic and wild birds in Utah.

“When we first got it, we think it came over the polar ice caps into the U.S. After we had it in North America, it went south, it hit South America,” said Amanda Price, state veterinarian with the Utah Department of Agriculture and Food. She said this strain has continued to circulate since 2022, mostly spread by migratory birds.

“So, in the fall, it'll hit the northern states first, and then kind of track southward as it goes,” Price said.

In addition to wild birds, the virus can infect domestic flocks and dairy cattle. While Utah’s poultry and cattle have been impacted in the past, there are no current infections.

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Video: Five Confirmed New World Screwworm Cases Raise Alarm for Livestock and Pet Owners

Pat Hoffmann, Swine Technical Consultant at Elanco Animal Health tells us about the impact of New World Screwworm. The emergence of New World screwworm in the U.S. creates a threat for veterinarians, livestock producers and pet owners that has not been seen north of the Florida Keys since the fly was eradicated from the United States more than 50 years ago. New World screwworm (Cochliomyia hominivorax) larvae feed on living tissue and can affect a wide range of warm-blooded animals, including livestock, companion animals, wildlife, and even humans.
“New World screwworm could have a devastating impact on animal health, welfare, and producer livelihoods,” said Jeff Simmons, President and CEO, Elanco Animal Health. “We want to thank the FDA, EPA and USDA, for all their work to prepare for this threat. We’re committed to supporting our customers during this challenging time by delivering innovation, scientific expertise, and available resources to help treat New World screwworm and support the health and well-being of animals.”
Elanco is working alongside the U.S. animal health industry to help them fight against this parasite, offering a portfolio of options for pets and livestock that can help treat New World screwworm larvae infestations.