Chicken culling, disposal raise concern as bird flu spreads
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[July 18, 2024]
By Leah Douglas
(Reuters) - The spread of bird flu among poultry and dairy farms has
heightened some health experts' concerns that the process of killing and
disposing of poultry infected with the virus may pose a risk to humans
and livestock.
Recent instances of farms dumping carcasses in landfills and using
methods to kill chickens that put workers in close proximity to the
virus show how the process of getting rid of infected birds could
further spread the disease, according to data obtained by Reuters and
interviews with officials and disease experts.
Extreme heat that made it difficult to keep protective equipment on
during the asphyxiation by carbon dioxide of chickens on a Colorado egg
farm likely contributed to five bird flu cases among workers, the
largest cluster of human cases in the United States, the Centers for
Disease Control (CDC) and Prevention said this week.
The situation highlights the need for systematic use of protective gear
when killing the sick animals, said the CDC's Principal Deputy Director
Nirav Shah on a Tuesday call with reporters about the outbreak.
Workers killing chickens risk inhaling the virus, said Dr. Michael
Osterholm, an infectious disease expert at the University of Minnesota,
of the process. The workers had mild symptoms including pink eye and
respiratory issues.
"Depopulation activities need to clearly focus on protection for these
individuals," he said.
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So far, there have been no human or livestock cases linked directly to
disposal of animals with avian flu.
COLORADO'S CASE
Bird flu has migrated to nearly every U.S. state over the past 2.5
years. There have been nine cases among poultry and dairy workers since
March, including the Colorado poultry workers.
Further bird flu spread among livestock could increase the likelihood of
human infections, though the risk to the general public is still low,
officials from the CDC have said.
About 95 million chickens, turkeys, and other poultry have been killed
and disposed of since February 2022, according to U.S. Department of
Agriculture data obtained by Reuters showing culling and disposal
methods through late June.
Bird flu is fatal in birds and the government requires entire flocks to
be culled once the virus is on a farm. The deadliest year was 2022, but
nearly as many chickens have been disposed of so far in 2024 as in all
of 2023, the data shows.
The sick workers in Colorado, for instance, were killing the birds with
mobile gas chamber carts, said Julie Gauthier, an official at USDA's
Animal and Plant Health Inspection Service, on the Tuesday call.
The carts can typically accommodate between a dozen and 50 birds and
workers asphyxiate them batch by batch, Gauthier said. A USDA
spokesperson said the agency had reviewed the farm's use of the method
as part of its response to the outbreak.
More than 150 of the workers were exposed to infected poultry, 69
displayed symptoms and were tested, and five were positive, said
AnneMarie Harper, communications director at the Colorado Department of
Public Health and Environment.
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Test tubes is seen labelled "Bird Flu" words in front of stock graph
in this illustration taken, June 10, 2024. REUTERS/Dado Ruvic/Illustration/File
Photo
![](http://archives.lincolndailynews.com/2017/Jul/22/images/ads/current/rohlfs_lda_072017.png) Most chickens are killed by
asphyxiation either with portable chambers like those used in
Colorado, or by spraying a firefighting foam on the birds or
shutting down ventilation to the chicken barns, the USDA data shows.
A small number are killed with firearms, by cervical dislocation, or
other means.
DISPOSING OF THE DEAD
Most of the culled birds are composted, either in chicken houses or
on farms, or buried, according to the USDA data. To compost the
birds, farmers cover them in material like wood shavings, maintain
the compost piles at a high temperature, and stir them occasionally
with farm equipment in a process that typically takes several weeks.
Federal and state officials work with farmers to determine the best
disposal methods, said John Clifford, a former USDA chief
veterinarian, now an advisor for the USA Poultry and Egg Export
Council, an industry group.
It is safest to compost on site to avoid moving the carcasses and
potentially spreading the virus, said Myah Walker, compliance unit
supervisor at the Minnesota Board of Animal Health.
In rarer cases, carcasses are transported to landfills, a process
that can meet some federal and state regulations.
Michigan egg producer Herbruck's Poultry Ranch disposed of nearly 2
million chickens between April 15 and June 8 in private landfills,
according to USDA data and Michigan state records of the disposal
process obtained by Reuters.
Herbruck's declined to comment.
Just 3% of all poultry have been disposed of in landfills since
2022, and the Herbruck's outbreak accounts for about two-thirds of
them, the USDA data shows.
Soon after the Herbruck's disposal, a dairy farm near one of the
landfills tested positive for bird flu, alarming area farmers. Even
so, whole genome sequencing showed the disposed Herbruck's carcasses
did not cause the infection, said Adeline Hambley, Ottawa County's
health officer.
Wild birds have helped spread the virus between poultry farms and to
other species.
Brian Hoefs, the state veterinarian for Minnesota, said he would not
recommend disposing of dead poultry in landfills.
"That's the restaurant for scavengers. It would be a recipe for
disaster," he said.
(Reporting by Leah Douglas in Washington; additional reporting by
Julie Steenhuysen, P.J. Huffstutter, and Tom Polansek in Chicago;
Editing by Anna Driver)
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