California farmers euthanized nearly 3 million birds impacted by highly pathogenic avian influenza during the first week of December and more than 30 dairy herds tested positive for the disease, according to USDA.

In the past month, about 8.4 million birds in commercial operations and backyard flocks had been killed in California.

Bird flu also was confirmed in 227 herds of dairy cows in California during the past 30 days, bringing the state’s total to 506 dairies. No other states had outbreaks in that period.

Commercial bird outbreaks

In the largest outbreak of the past week, reported Dec. 5, a commercial table egg layer in Merced County euthanized 1.72 million chickens.

Another Merced County egg farm killed 794,000 birds due to avian influenza the same day.

The third largest outbreak of the week was Dec. 3 at a Fresno County commercial broiler farm, where 237,000 chickens were killed.

Overall during the week, California had 10 instances of bird flu that led to the death of 2.95 million birds, including 142,000 turkeys and 13,000 ducks.

West and Midwest

Highly pathogenic avian influenza has been spreading across the world since February 2022 and is widespread in wild birds.

Over the course of the outbreak, California is second in the nation with 17.2 million birds impacted.

Iowa leads the U.S. with 23.3 million birds impacted total, but it hadn’t reported an outbreak in the previous 30 days as of Dec. 9.

Arizona was second for cases in the past month with 791,000, followed by Minnesota with 296,000, South Dakota with 282,000 and Utah with 160,000.

Washington had one backyard flock infected in the past month as of Dec. 9 with 40 birds killed.

Oregon had two backyard flocks affected, and 38 birds were impacted, and Idaho has had one backyard flock affected with 20 birds euthanized.

Human cases

The U.S. has had 58 cases of humans infected with highly pathogenic avian influenza, and California leads the nation with 32 instances.

All but one were exposed via cattle, and it isn’t clear how that individual became sick, according to the U.S. Centers for Disease Control and Prevention.

Washington is second in the nation with 11 human cases, all exposed through poultry.

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