Chickens raised for slaughter

Bird Flu Is Slamming Factory Farms But Sparing Backyard Flocks. Why? – Tom Philpott

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.

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