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Disease outbreak: Fall migration increases HPAI occurrence

by Wyoming Livestock Roundup

Following a summer absent of both domestic and wild birds testing positive for highly pathogenic avian influenza (HPAI), the disease has recently been confirmed in Wyoming along with major losses to domestic poultry flocks in Colorado. Several detections since mid-September have prompted producers to increase biosecurity practices and monitor flocks closely. 

“Cases of HPAI are on the rise again across the country as migratory birds start their seasonal movement south,” said Colorado State Veterinarian Maggie Baldwin. “The most important thing bird owners can do right now is limit interaction between their flocks and wild birds.” 

According to the Center for Disease Control and Prevention, the risk of HPAI to the general public is low, though people should use caution when handling sick or dead birds. 

Colorado layer losses

HPAI outbreaks have devastated Colorado’s laying hen population, as producers work to rebuild flocks from the loss of millions of birds this spring. 

In April, the virus impacted an operation in Montrose County with 58,000 birds, as well as a producer in Weld County with 1.4 million birds. At the time, Colorado Gov. Jared Polis issued an executive order to declare an emergency and set aside $1 million for the response. 

On Sept. 21, HPAI was positively detected in a commercial egg laying facility in Weld County, affecting 1.1 million layers. Following the incident, Polis declared a disaster again, allowing state agencies another six months to use the remainder of funds allocated by the initial emergency declaration. 

“Right now, it’s critical Colorado’s backyard and commercial poultry flock owners keep up the biosecurity measure they have been implementing since the beginning of the outbreak this spring,” Baldwin said. “HPAI is a disease with high mortality which can wipe out entire domestic poultry flocks in less than 72 hours. The most important thing bird owners can do right now is limit interactions between their flocks and wild birds.”

Wyoming HPAI cases

Cases of HPAI returned to Wyoming in September, following initial detection in March 2022.  The University of Wyoming (UW), the Wyoming State Veterinary Laboratory (WSVL) and the Wyoming Game and Fish Department’s Wildlife Health Laboratory detected eight positive cases of HPAI in wild birds since Sept. 16. These birds include a blue-winged teal and a great horned owl, as well as two turkey vultures found on the UW campus. 

The WSVL noted the greatest risk of transmission is wild birds, especially waterfowl. The peak of fall bird migration in the state is late September through mid-November, and producers are encouraged to increase biosecurity practices if they live near a water attractant. 

If producers experience illness or death in their domestic flocks or pet birds, they are urged to contact a veterinarian to determine if the animals may be infected with HPAI and can arrange to submit samples for testing. Additionally, if waterfowl or domestic poultry show signs of illness or unexplained death, they may contact the Wyoming Livestock Board at 307-777-7515.

Averi Reynolds is a corresponding writer for the Wyoming Livestock Roundup. Send comments on this article to

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