Are chicken flocks only culled in the US?
I ran into typical MAGA disinformation on the Internet the other day. The post stated "not a single chicken" had been killed in Canada or Mexico due to the bird flu compared to millions in the US. Since all the social media sites have been captured by MAGA I decided to do the obvious debunking of a post that stated – only flocks of chickens with avian influenza in the US are culled and not chickens in Canada or Mexico. After reading pandemic misinformation for the past 5 years – it seemed like this was obvious and I was not wrong.
The latest North American bird population estimates were
about 7 billion birds in 529 species in 2019 (1,2). That represented a decline of about 3 billion
birds since 1970. Habitat loss,
ecosystem destruction, and climate change were considered significant factors
according to these authors. Anthropogenic threats like collisions with vehicles
and other manmade structures, poisoning, and predation by domestic animals was
also estimated to be a significant factor. Domestic cats kill roughly 1.3 to 4
billion birds annually (3). By comparison the estimate of bird deaths from
contact with windmills is about 140,000 – 328,000 annually (4).
Considering the chicken population in all 3 countries – the
US has a total of 1.53 billion chickens annually that includes 1.2 billion
broiler chickens alive at any one time and about 350,000 egg laying chickens.
The total
chicken population in Canada is 173.94 million. In Mexico the total chicken population is
611.2 million.
Meat, poultry, and egg production in the US is regulated by
the USDA and the Poultry Products Inspection Act (PPIA) that includes other
poultry like geese, ducks, guinea hens, and other more exotic domesticated
birds. In Canada it is the Canadian Food
Inspection Agency (CFIA). In Mexico it
is the Ministry of Agriculture and Rural Development. The culling of domestic chickens because of
avian influenza has become a contentious political issue and a source
of right wing misinformation. Additional misinformation has included blaming
the Biden administration for culling chickens and driving up egg prices. The
question of how these decisions get made, especially when large numbers of
infected chickens are euthanized has been answered by experts in the past. Here is one quote from CBS News when asked
about the loss of 148M poultry since 2022:
"It's a staggering number, there is no doubt,"
said Jodie Guest, a professor of epidemiology with Emory University's Rollins
School of Public Health in Atlanta. "But it is, and always has been a
policy across administrations, with the USDA, that this is how they handle
infections like this among poultry. And as we've seen bird flu move [across]
species, it becomes even more important to try to contain that infection in the
flocks that it's in, so that we don't continue to see spread."
The USDA has an infographic
on measures to contain avian influenza outbreaks. From that page “Birds are destroyed
usually within 24–48 hours of detecting the disease. USDA pays for birds that
must be destroyed.” The cost of a
live chicken can range from $5 to $20. There
seems to be a question about whether infected birds need to be euthanized. This is the rationale
provided by the American Veterinary Medical Association (AMVA):
“Recovery of poultry from HPAI is extremely rare.
Infected poultry typically are euthanized and poultry products destroyed when
HPAI infection is confirmed. The outcome also may be influenced by the
producer’s participation in secure food supply plans. If regulatory officials
authorize you to treat, keep in mind that the FDA prohibits extralabel use of
adamantine and neuraminidase inhibitor classes of antiviral drugs in chickens,
turkeys, and ducks.”
HPAI in this case is Highly Pathogenicity Avian Influenza are defined as causing high mortality in poultry and are H5 and H7 influenza viruses although not all viruses belonging to those classes are highly pathogenic. There are also Low Pathogenicity Avian Influenza (LPAI) viruses that may not cause any symptoms in affected birds. There is the possibility that LPAI viruses can mutate into HPAI viruses and they are monitored for that reason. In the US – ill or deceased domestic birds are typically reported at the state level to animal health officials. They decide what level of analysis needs to be done and recommend protective measures. Any casual search of previous outbreaks in avian populations will also reference significant culling of domestic fowl in all three countries.
In the US, 148M domestic birds have been euthanized due to
the latest outbreak of avian influenza including 20M egg laying chickens. Exact numbers of euthanized poultry in Mexico
since 2022 are harder to come by but are in
the millions. In Canada the
number is about 14.5M. I have not
found a site that examines the differences in euthanized poultry between
countries. Variability will vary
depending on wild bird exposure, total population of domestic birds exposed, size
of the domestic flock, biosecurity measures, and farm density.
In summary, there is a consensus about approaches to HPAI in
domestic birds. There is really no evidence that either Canada or Mexico does
not recommend euthanizing infected birds. From a veterinary medicine standpoint,
it does not make sense – because most of the HPAI infected population dies and they
act as a source for further mutations and facility contamination. The discrepancies
in the total populations euthanized is all 3 countries may be because of
policies (reimbursement for dead birds in the US), levels of oversight (state
and federal in the US), and varying levels of reporting. There is no evidence that the culling of
birds is due to a political initiative or an initiative to adversely impact the
economy. And why would any rational President want to do that?
George Dawson, MD, DFAPA
References:
1: Pennisi E.
Billions of North American birds have vanished. Science. 2019 Sep
20;365(6459):1228-1229. doi: 10.1126/science.365.6459.1228. PMID: 31604214.
2: Rosenberg KV,
Dokter AM, Blancher PJ, Sauer JR, Smith AC, Smith PA, Stanton JC, Panjabi A,
Helft L, Parr M, Marra PP. Decline of the North American avifauna. Science.
2019 Oct 4;366(6461):120-124. doi: 10.1126/science.aaw1313. Epub 2019 Sep 19.
PMID: 31604313.
3: Loss SR, Will T,
Marra PP. The impact of free-ranging domestic cats on wildlife of the United
States. Nat Commun. 2013;4:1396. doi: 10.1038/ncomms2380. PMID: 23360987.
4: Loss SR, Will T,
Marra PP. Estimates of bird collision mortality at wind facilities in the
contiguous United States. Biological Conservation. 2013 Dec 1;168:201-9.
5: Ornelas-Eusebio E,
García-Espinosa G, Laroucau K, Zanella G. Characterization of commercial
poultry farms in Mexico: Towards a better understanding of biosecurity
practices and antibiotic usage patterns. PLoS One. 2020 Dec 1;15(12):e0242354.
doi: 10.1371/journal.pone.0242354. PMID: 33259478; PMCID: PMC7707464.
6: CDC site on Avian
Influenza (map of counties affected): https://www.cdc.gov/bird-flu/situation-summary/data-map-commercial.html
7: CDC site: 2020-2024 Highlights in the History of Avian
Influenza (Bird Flu) Timeline. https://www.cdc.gov/bird-flu/avian-timeline/2020s.html
8: Barman S, Turner JCM, Hasan MK, Akhtar S, Jeevan T,
Franks J, Walker D, Mukherjee N, Seiler P, Kercher L, McKenzie P, Webster RG,
Feeroz MM, Webby RJ. Reassortment of newly emergent clade 2.3.4.4b A(H5N1)
highly pathogenic avian influenza A viruses in Bangladesh. Emerg Microbes
Infect. 2025 Dec;14(1):2432351. doi:
10.1080/22221751.2024.2432351. Epub 2024 Dec 9. PMID: 39584394; PMCID:
PMC11632930.
Details of the specific viral analysis for HPAI are
included in this paper
No comments:
Post a Comment