By JONEL ALECCIA AP Health Writer
In a concerning development, two cats owned by Michigan dairy workers succumbed to bird flu after being infected with the H5N1 virus. However, uncertainties remain about how these cats were infected and whether there was any virus transmission to humans in their respective households, according to a recent study.
The study, published by the U.S. Centers for Disease Control and Prevention, highlights a lack of detailed evidence to determine if humans can transmit the H5N1 virus to domestic cats or vice versa. Dr. Diego Diel from Cornell University College of Veterinary Medicine remarked, “I don’t think there is any way of concluding that there was human-to-cat transmission based on the data that is presented.”
Both cats, residing in separate households, died in May after severe illnesses were confirmed as the Type A H5N1 virus, commonly found in U.S. dairy herds. Notably, both cats were indoor-only, with no known exposure to infected cattle or birds, and they did not consume raw milk.
In one case, a cat belonging to a dairy farm worker in a bird flu-affected county developed illness and tested positive for H5N1, leading to euthanasia. A second cat in the same household fell ill but recovered, while a third remained healthy and tested negative. An adolescent in the household also experienced illness but tested negative for flu.
In the second household, the deceased cat belonged to a dairy worker who frequently handled raw milk and reported eye irritation prior to the cat's illness. The pet was known for rolling in the worker's contaminated clothing and died shortly after showing symptoms. Another cat in this household tested negative for the virus.
In both scenarios, the dairy workers opted against testing for H5N1, leaving direct transmission pathways speculative. Dr. Keith Poulsen from the Wisconsin Veterinary Diagnostic Laboratory suggested that the cats likely contracted the virus from contaminated clothing, boots, or hands, rather than direct human-to-cat transmission.
The study concluded that while bird flu infections in indoor cats are rare, these cases highlight the potential risk for human infection. Recent reports have shown domestic cats dying after consuming unpasteurized milk or pet food contaminated with bird flu.
Experts, including Dr. Poulsen, emphasize the necessity for comprehensive testing for H5N1 across various environments to better understand and mitigate the risk of bird flu transmission.
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