Why Is Bird Flu Hitting Millions of CAFO Birds but Sparing Backyard Flocks?

Editor’s Note: Bird flu is hitting an unprecedented number of CAFO lot chickens right now, but the situation is being reported in the mainstream media as a mystery. Why are backyard flocks escaping the virulent bird flu that’s wiping out millions of caged birds in biosecure metal buildings? Is it because birds raised in fresh air and sunshine are more capable of fighting off viruses? If that was true then why are the wild waterfowl: ducks and geese,  etc., catching the deadly flu? Or maybe they’re not. Something is just not adding up here…

The Midwest’s ongoing avian flu crisis is wreaking havoc on the region’s large-scale egg and turkey farms. Last week alone, the US Department of Agriculture confirmed that the virus had turned up in more than 20 additional facilities in the region, condemning 4 million birds to euthanasia. Altogether, the H5N2 virus—”highly pathogenic” to birds, so far non-threatening to humans—has affected 168 sites and a jaw-dropping 36 million birds, the great bulk of them in Iowa and surrounding states. It’s the largest avian flu outbreak in US history—and it has already wiped out 40 percent of the egg-laying flock h Iowa, the number-one egg-producing state in the US, according to The New York Times.

But it’s largely leaving backyard flocks unscathed. Why?

According to Hon S. Ip, a virologist at the US Geological Survey’s National Wildlife Health Center, it’s a genuine mystery. Backyard flocks typically roam outdoors, in ready contact with wild birds, which are thought to be the origin of the virus. Their commercial counterparts live in tight confinement under strict “biosecurity” protocols: birds are shielded from contact with the outdoors; workers change into special boots and coveralls—or even shower—before entering facilities, etc.

Ip said that wild birds could be spreading the virus in one of two ways: directly, by bringing chickens and turkeys into contact with infected feces; or indirectly, through wind-borne particles that, say, blow through vents in a confined facility. “If that’s how it’s spreading, you’d expect backyard flocks to be widely affected too, but they don’t seem to be,” he told me. Moreover, it has continued to spread in Iowa, even after the egg industry had ample time to ramp up biosecurity. All of this suggests something else, besides wild birds, might be the cause, Ip added.

But what? He has no idea, he said. And nor, apparently, does anyone else.

(read more at Mother Jones)

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Contributed by Tom Philpott of Mother Jones.