If current infection trends hold, the effects of deadly and highly contagious avian influenza outbreaks in the United States will not exceed those of 2015, when more than 50 million birds were culled, according to the country’s top agriculture official.
“In terms of the nature of the outbreaks, the size of the operations that have been impacted, the number of states that are dealing with backyard operations as opposed to commercial-sized operations, would strongly suggest that when this is all said and done it’s going to be significantly less than what we experienced in 2014-15,” U.S. Secretary of Agriculture Tom Vilsack said Tuesday in a call with reporters.
There were 18 new virus detections in flocks in 10 states Tuesday, the most this year in a single day, according to U.S. Department of Agriculture data.
Wild, migrating birds are the likely sources of the virus, especially waterfowl. They can be infected and asymptomatic, whereas the virus is often fatal for domesticated poultry.
Vilsack said stricter security measures at poultry facilities and heightened containment efforts after virus detections have greatly reduced the potential for infections and the risk of transporting the virus from one facility to another. That key strategy emerged from the bird flu outbreak seven years ago.
No such site-to-site infections have yet been identified in Iowa, said Chloe Carson, a spokesperson for the Iowa Department of Agriculture and Land Stewardship. Yet, she was hesitant to share in Vilsack’s optimism about how the outbreaks will proceed.
“It’s just too early to tell in the migration season,” Carson said. “We’re hopeful that that is correct and we can continue to control the spread, but we can’t speculate.”
Infected flocks are culled as soon as possible, and most or all of them have been disposed of on-site through burial or composting. The virus is unlikely to infect humans, and meat and eggs from infected birds are destroyed.
Other countries have imposed import restrictions on U.S. poultry products, but they have been more targeted than in 2015, Vilsack said.
“There has not been an effort to do a nationwide restriction, and I think that’s positive,” he said.
Top importers of U.S. poultry meat — Mexico and China — have restricted trade by state, and another, Canada, limited its restrictions to areas that extend about six miles from infected sites, according to the USDA.
Iowa is in the throes of peak migration for ducks, a significant carrier of the virus. Geese that are headed to their northern breeding grounds are largely gone already.
Bird flu in 2022 and 2015
There are notable differences between the outbreaks of 2014-15 and 2022, nationally and in Iowa.
In the former outbreak, the virus was detected in 15 states, from the Midwest to the west coast. This year, it has been found in a total of 24 states so far, primarily from the Midwest to the east coast.
The first detection was earlier in the former outbreak — in December 2014 — than the current one — in February 2022. And the average size of affected flocks is smaller this year — about 162,000 per flock versus about 215,000 per flock in the former outbreak.
The total number of birds of infected flocks culled so far this year is 23.8 million, about half that of 2015. But bird migration is still expected to persist for many weeks.
Here’s a similarity: Iowa accounted for two-thirds of the total affected birds in the former outbreak, and it accounts more than half of the birds affected so far this year. The state is particularly at risk because of its large flocks. Two commercial poultry operations that were infected this year had more than 5 million birds apiece.
The detections in Iowa started about six weeks earlier this year: March 1 compared with April 13 in 2015. Even though the outbreaks in 2015 had a later start, its early rate of infection was about double.
In the first five weeks of this year’s detections in Iowa, there were 15 infected flocks and 13.3 million affected birds.
In the first five weeks of 2015’s detections in Iowa, there were 53 infected flocks and 27.4 million affected birds.
The 2015 detections peaked in Iowa during a week in early May that had 25, nearly a third of the state’s total detections that year.
“We are hopeful that once migration season has passed and we see warmer temperatures, we will see the virus leave the state,” Carson said.
The 16 detections so far this year in Iowa include:
— March 1: A backyard flock of 42 chickens and ducks in Pottawattamie County.
— March 6: A commercial flock of about 50,000 turkeys in Buena Vista County.
— March 10: A commercial flock of about 916,000 egg-laying chickens in Taylor County.
— March 17: A commercial flock of more than 5.3 million egg-laying chickens in Buena Vista County.
— March 20: A backyard flock of 11 chickens and ducks in Warren County.
— March 23: A commercial flock of about 54,000 turkeys in Buena Vista County.
— March 25: A commercial flock of about 250,000 young hens in Franklin County.
— March 28: A commercial flock of about 28,000 turkeys in Hamilton County.
— March 28: A commercial flock of about 1.5 million egg-laying chickens in Guthrie County.
— March 29: A commercial flock of about 35,500 turkeys in Buena Vista County.
— March 31: A commercial flock of more than 5 million egg-laying chickens in Osceola County.
— March 31: A commercial flock of about 88,000 turkeys in Cherokee County.
— April 2: A commercial flock of about 37,000 turkeys in Sac County.
— April 2: A commercial flock of about 15,000 breeding chickens in Humboldt County.
— April 4: A commercial flock of about 8,000 turkeys in Hamilton County.
— April 5: A commercial flock of about 46,000 turkeys in Hardin County.
Iowa Capital Dispatch is part of States Newsroom, a network of news bureaus supported by grants and a coalition of donors as a 501c(3) public charity. Iowa Capital Dispatch maintains editorial independence. Contact Editor Kathie Obradovich for questions: info@iowacapitaldispatch.com. Follow Iowa Capital Dispatch on Facebook and Twitter.
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