Seven cases of H5N1 avian flu have been reported in Michigan since Dec. 16. The first case was discovered at a poultry facility in Ottawa County.
Avian flu circulates in wild birds and can infect poultry, causing illnesses classified as highly or low pathogenic. Michigan's first cases in 2022 introduced a highly pathogenic strain.
Dr. Kimberly Dodd, dean of the College of Veterinary Medicine at Michigan State University and an infectious disease expert, explained why the initial outbreak was unique.
"Generally, once it comes to wintertime the number of cases drop off and sometimes that's all we see at the outbreak, and it's resolved," Dodd noted. "In this case, the outbreak continued over the winter and spread across the entire country."
The recent outbreak has affected more than 340,000 birds. Early findings showed the virus also infecting wild mammals, especially young carnivores and scavengers, later spreading to marine mammals near infected waterfowl.
As of now, avian flu has been detected in 30 dairy cattle herds across Michigan. The initial case, reported in March 2024, marked the first instance of avian flu in dairy cattle in the U.S. Since then, the virus has spread to additional herds around the state. Dodd pointed out dozens of domestic and wild cats were also infected after the virus spread to dairy cattle.
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