Iowa study: Bird flu could spread to more species and humans via raw milk
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Bird flu has the potential to spread to more animal species and could mix with seasonal flu, making it easier to spread among humans, according to scientists behind a new study from Iowa State University.
Why it matters: Unpasteurized milk, which has become more popular in recent years, may carry a higher risk than previously thought.
Driving the news: The bird flu study examines how receptor distribution in the mammary glands of livestock and humans might influence its spread.
- Previous studies have not thoroughly examined the virus outside of the mammary glands of cattle, but consuming raw milk from other animals may also pose risks, according to the study.
State of play: The current public health risk from bird flu to humans remains low, according to the CDC.
Yes, but: The study, published Nov. 27 in the Journal of Dairy Science, suggests the disease could spread to other domestic animals, including pigs, sheep, goats and alpacas — raising concerns about more dangerous adaptations that could more easily affect humans.
By the numbers: Over 184 million domestic poultry have been affected since 2022, and the disease has impacted nearly 1,100 cow herds after spreading to cattle last year.
- There is no known person-to-person transmission of the disease at this time, but at least 71 people have been infected and two have died in the U.S.
Zoom in: Iowa legalized direct-to-consumer raw milk sales in 2023 after nearly 20 years of lobbying by advocates who argue it is healthy, helping with issues like respiratory ailments, especially in young children.
- The claims fail to withstand scientific scrutiny, according to information published by the U.S. Food and Drug Administration.
What they're saying: Store-bought milk in Iowa remains safe because it is pasteurized, but concerns about consuming raw milk should also apply to other types of animals, Rahul Nelli, the study's lead author and a research assistant professor at ISU, told the school's news service.
- "We need to try to stay ahead of this so it doesn't have a chance to continue to replicate and potentially evolve into something even more troublesome," said Todd Bell, a professor of veterinary pathology at ISU and a study co-author, per the news service.
The other side: Raw milk advocates have criticized previous news coverage as media hype, noting there are no known cases of bird flu in humans from drinking raw milk and that the illness in people and cattle is generally mild.
What's next: Researchers say increased surveillance of livestock — and more caution around raw milk — is crucial for spotting early signs of viral spread or adaptation.