Recent outbreaks of bird flu, or highly pathogenic avian influenza (HPAI), on poultry and dairy farms have raised concerns among health officials about the risks of current methods for culling and destroying infected birds. These concerns focus on the possibility that such processing could further spread the virus to humans and livestock. A July 19 Reuters report highlighted alarming practices such as dumping carcasses in landfills and using methods to kill chickens that expose workers to the virus.
Farm management monitored
Recent data seen by Reuters and interviews with officials and disease experts highlight the risks associated with current methods of disposing of infected birds. Farms disposing of carcasses in landfills have been criticized for potential environmental contamination and the risk of spreading the virus to other animals and humans. And the method of suffocating chickens with carbon dioxide has been criticized for requiring workers to get close to the birds and providing insufficient protection.
One particularly concerning case occurred at a chicken farm in Colorado, where hot weather made it difficult for workers to wear protective gear during the suffocation process, which likely contributed to “the largest cluster of human avian influenza infections in the United States,” according to Reuters. Five workers in Weld County contracted the virus. All reportedly had mild symptoms, including conjunctivitis, cough, sore throat and runny nose. No infected workers required hospitalization.
On July 8, Governor Jared Polis declared a verbal disaster emergency and the Colorado Department of Agriculture ordered the culling of 1.78 million chickens.
Colorado Case Study: A Closer Look
“Bird flu has spread to nearly every state in the U.S. over the past two and a half years. Nine cases have been reported among poultry and dairy workers since March, including among poultry workers in Colorado,” Reuters reported. The Colorado Department of Agriculture told the outlet that the decision on how to kill the birds is jointly made between the state, farmers and the U.S. Department of Agriculture (USDA). Julie Gautier, an Animal and Plant Health Inspection Service official with the USDA, explained that the infected workers in Colorado were using mobile gas chamber carts to kill the birds. The carts typically hold between 12 and 50 birds, and workers suffocate the birds in batches.
In Colorado, more than 150 workers came into contact with the infected poultry. 69 birds showed symptoms and five tested positive for HPAI, according to Ann-Marie Harper, public affairs director for the Colorado Department of Public Health and Environment. Most of the birds have been asphyxiated. Asphyxiation can be done using portable chambers like those used in Colorado, by spraying the birds with firefighting foam, or by cutting off ventilation in the chicken house, according to the USDA's HPAI response plan. Other methods include shooting, cervical dislocation, and other means.
Disposal of dead chickens
Reuters explained that most of the infected chickens are being used as compost.
Most culled birds are composted in their coops or on farms, or buried, according to USDA data. Farmers compost the birds by covering them with wood chips and other materials, keeping the compost piles hot, and stirring them occasionally with farm equipment, a process that typically takes several weeks.
John Clifford, a former USDA chief veterinarian and adviser to the U.S. Poultry Egg Export Council, stressed that federal and state officials work with farmers to determine the best disposal method. On-site composting is considered the safest way to avoid moving the carcasses and potentially spreading the virus, Mya Walker, compliance supervisor for the Minnesota Animal Health Commission, told Reuters.
In rare cases, carcasses are sent to landfills to meet federal and state regulations, but the practice has come under criticism.
Herbrooks Poultry, the 10th largest egg producer in the US, disposed of about 2 million chickens in a private landfill between April 15 and June 8, according to USDA data and Michigan state records cited by Reuters. This disposal method raised concerns when a dairy farm near one of the landfills tested positive for avian flu, but the outlet reported that “whole genome sequencing indicated that discarded Herbrooks chicken carcasses were not the source of the infection.”
Another risk is the spread of viruses from carcasses to wild birds. Minnesota veterinarian Brian Hofs warned that dumping dead poultry in garbage dumps is a “potential disaster” because it attracts scavengers.
Risks to people
According to the Centers for Disease Control and Prevention (CDC), the risk of avian flu to the general public remains low, with only nine cases of human infection reported in three states since 2022.
At the same time, the mass culling of chickens has raised concerns about food supplies and prices. According to Reuters, about 95 million chickens, turkeys and other poultry have been culled since February 2022. While the deadliest year was 2022, the number of chickens culled so far in 2024 is roughly the same as in all of 2023.
The above barbaric chicken culling methods seem especially unnecessary, since the USDA food safety guidelines state that avian influenza-infected chickens and eggs are safe as long as they are properly cooked. According to the USDA, cooking the birds to an internal temperature of at least 165 degrees Fahrenheit kills the virus and other pathogens. However, handling raw birds can be dangerous if proper hygiene and food safety practices are not followed. They emphasize the importance of thoroughly washing hands, utensils, and surfaces after handling raw birds to prevent cross-contamination.
According to the CDC, highly pathogenic avian influenza (HPAI) H5N1 has been confirmed in 163 dairy herds in 13 states. Avian influenza has been detected in more than 104,050,000 wild waterfowl, commercial poultry, and household or hobbyist chicken flocks in 48 states since January 2022.
Western countries believe the H5N1 virus has a high chance of causing a pandemic because of its ability to mutate, and are ramping up vaccine production.
