‘Existential’ avian flu outbreak forces US egg farmers to kill entire flocks

Highly contagious virus has particularly ravaged California's Sonoma county, know as the Egg Basket of the World'

Last month, Mike Weber got the news every poultry farmer fears: his chickens tested positive for avian flu.

Following government rules, Weber's company, Sunrise Farms, had to slaughter its entire flock of egg-laying hens - 550,000 birds - to prevent the disease from infecting other farms in Sonoma county north of San Francisco.