February 9, 2023
From skyrocketing prices to empty shelves in the egg section of grocery stores, the impact of the avian influenza outbreak is being felt far beyond the agricultural industry.
Nearly 6.4 million birds in Colorado and 2.2 million in Utah have died since April 2022 in an outbreak that Colorado State University's Dr. Kristy Pabilonia called the worst she’s seen in the U.S. in her two-decade career monitoring avian diseases.
In Utah, the total includes eight non-commercial poultry flocks, 18 commercial egg layer and turkey flocks, and one commercial gamebird facility. Non-commercial detections in backyard chicken flocks and petting zoos have occurred in Cache, Utah, Salt Lake, and Weber counties.
Live wild bird surveillance has shown the virus in various dabbling duck species, including the mallard, gadwall, cinnamon teal, green-winged teal, Northern shoveler, and American widgeon. Wild bird morbidity surveillance has detected the virus in owls, hawks, gulls, pelicans, eared grebe, black-crowned night heron, and the turkey vulture.
"The most prevalent species with HPAI has been the Canada goose," wrote David Frame, an Extension poultry specialist at Utah State University. "This is significant because waterfowl are the natural carriers of avian influenza viruses and typically do not die as a result of the virus; however, the current strain of HPAI is lethal enough to kill even waterfowl.
"Although we have been fortunate to have HPAI detections drop this winter, some areas of the country have not been so lucky," he wrote. "As we approach the spring months, it is uncertain whether we will experience another wave of outbreaks during spring migration. Work still needs to be done to determine exactly how the initial introduction of HPAI occurs.
"What we do know is that once introduced, the virus is transmitted from flock to flock through contaminated equipment and people."
Pabilonia is the director of Clinical Diagnostics for CSU's Veterinary Health System of the College of Veterinary Medicine and Biomedical Sciences. She is an expert on diseases of poultry, and has worked closely with a number of international, state and federal agencies on foreign animal and zoonotic disease issues.
She spoke to CSU's news service about the 2022 avian flu outbreak, the outlook going forward and why you should think twice before starting a flock of backyard chickens right now.
Even though the latest avian flu outbreak was first reported in the U.S. in early 2022, it’s reentered the headlines this year due to egg prices. What do you want people to know about the ongoing situation?
The original lineage of this virus was first detected in 1996 in China, and it’s changed over time, much like how the COVID-19 virus has evolved.
The last U.S. outbreak of highly pathogenic avian influenza virus was in 2014-15, and in that case, it mostly infected commercial poultry but there were only a handful of infections in wild birds, which made it easier to stamp out the outbreak.
What’s different about the most recent outbreak is we’ve detected the virus in thousands of wild birds in the U.S., which makes it much more difficult to control, since these species migrate globally, making them really good at spreading the virus.
Most of the cases in commercial and backyard poultry are the results of wild bird introduction of the virus, making it very difficult for producers to prevent introduction of the virus into their flocks. It’s also a very deadly virus, and agricultural officials are working to depopulate flocks where the virus is detected and dispose of the bodies properly.
Colorado has lost almost its entire egg-laying population during this outbreak, which is why egg prices are as high as they are and there’s a lower supply.
The other thing to note is that because the virus is in wild birds it’s now not possible to fully stamp the virus out of the U.S, so we’re focusing efforts on preventing transmission from wild birds to domestic poultry.
How exactly do wild birds spread the virus to domesticated ones?
Avian influenza virus spreads similarly to the flu in humans by transmitting bird to bird. Birds can shed the virus in their respiratory and fecal secretions. People can also play a role in spreading the virus, such as foot traffic contaminated by bird droppings or contaminated clothing and equipment.
The reservoir for avian influenza viruses are waterfowl and shorebird populations. It’s a smart virus, because it has picked a reservoir species that commingle with each other and migrate all over the world.
It’s inherently a very contagious virus, and when you get one sick bird in a commercial operation, it spreads very quickly.
But again: We’re not just seeing this virus in commercial operations. We’re seeing it in backyard flocks too.
There’s been chatter on social media from people who are considering raising backyard chickens to avoid buying the expensive eggs in stores. You’re saying that might not be the best solution?
I don’t recommend getting backyard flocks at this time due to the risk of highly pathogenic avian influenza. I support backyard chickens, but now’s not the best time to start your flock. It’s very hard to keep wild birds out of your backyard, and I don’t recommend raising chickens inside due to the potential spread of pathogens from birds to humans.
If you already have backyard chickens, I recommend protecting them from wild birds getting into their areas, such as keeping them cooped up as much as possible and netting over their outside spaces. We’re even detecting avian flu cases in small birds like crows or ravens, which are easily able to get into small areas.
What’s the risk of humans getting sick from the avian flu?
The Centers for Disease Control and Prevention is only listing one human case of the avian flu in the U.S. during this outbreak, and there have been scattered cases in other countries. So far, it’s been encouraging, but we don’t want the virus to evolve and be able to spillover to humans more easily.
What are scientists like you doing to monitor the avian flu outbreak?
The CSU Veterinary Diagnostic Laboratory in Fort Collins is a Tier I lab with the USDA’s National Animal Health Laboratory Network (NAHLN), and is currently testing wild and domestic birds for the avian flu. We get samples from all over the U.S., and have run more than 10,000 tests since the outbreak began. The VDL also coordinates the Colorado Avian Health Program, which provides avian health services to commercial producers and backyard flock owners throughout Colorado. This program has been very involved educating producers and owners, collecting samples and aiding in the response to positive flocks.
We’ve worked with many state and federal agencies, including the Colorado Department of Agriculture, Colorado Parks and Wildlife and the U.S. Department of Agriculture, to monitor the presence of the virus in our wildlife and domestic bird populations, as well as the monitoring for the virus in other captive populations such as zoo birds.
This Colorado Avian Health Program has a hotline number for questions related to avian influenza or other general poultry disease: (970) 297-4008. For more information, go to col.st/OmEjp.
Source: Colorado State University, Utah State University
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