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Stop blaming wild birds. The bird flu is our fault.

Pigs and cows are generally only tested when they become ill; it is usually up to their veterinarian to decide whether and which tests they order. “Unlike the poultry and egg industry, where no influenza viruses are tolerated, influenza A viruses are very well tolerated on all U.S. swine operations,” said Gregory Gray, professor of diseases. Infectious Diseases at the University of Texas Medical Branch and researcher. a public health doctor who studies zoonotic respiratory viruses told me this. “There is no systematic sampling of every pig placed on the market for influenza viruses, and no sampling on farms for influenza viruses unless there is illness.”

This is dangerous because pigs are known as “mixing bowls” for flu viruses; they have similar receptors to humans and can mix and match different variants that could spread well among humans. The more densely populated pig farms are, “the greater the variety of influenza A virus variants,” Gray said. Cows may also have a similar mix of receptors, according to new research that has not yet been peer-reviewed or published.

While bird flu hits poultry hard, it is possible that pigs and cows, which have a less deadly course, can spread the virus with few or no symptoms. “Unfortunately, what always happens with surveillance efforts is that they are expensive: resources are limited,” Leibler said. Monitoring wastewater, including manure and trash from commercial food facilities, could be helpful. But that would require some involvement from farms, which have been reluctant to test.