Key Takeaways
- New bird flu cases were recently detected in poultry workers in Colorado.
- Public health officials said that extreme heat may indirectly have played a role in the spread.
- As of now, bird flu has not spread between humans.
Extreme heat is a health hazard for several reasons, ranging from dehydration to its impact on medication. Now, public health officials are adding bird flu to the list as they investigate whether high temperatures might be exacerbating the spread of the virus.
At least six poultry workers in Colorado contracted bird flu after culling a flock of chickens that had tested positive for H5N1 this month. Temperatures reached 104 degrees Fahrenheit outside and were even hotter in the chicken houses, according to a press briefing.
Workers had difficulty keeping goggles and masks sealed onto their faces due to sweat and industrial fans. Those fans also spread feathers and debris, which can carry the virus.
“Extreme heat makes it very uncomfortable to wear appropriate personal protective equipment (PPE), and necessitates the use of fans that blow possible infectious debris around,” infectious disease expert Amesh A. Adalja, MDsenior scholar at the Johns Hopkins Center for Health Security, told Verywell.
Adalja said the H5N1 influenza strain that’s causing bird flu isn’t getting more transmissible as temperatures climb. Rather, the issue is that the workers were doing their job “in a high-risk environment without full PPE.”
Since April 2024, health officials have detected 10 human cases of bird flu in the U.S. Each case has occurred in people with close exposure to cows or chickens, and no cases have been spread from human to human.
How Bird Flu Spreads
Bird flu can spread from infected animals to humans in a few different ways, such as by touching something that’s contaminated with the live virus and then touching your nose, mouth, or eyes. You can also contract bird flu if a liquid that’s contaminated with the virus, like milk from an infected cow, splashes into your eyes.
Eating, drinking, or inhaling droplets that are contaminated with the live virus can also make you sick. In the case of chickens and other poultry, the feathers can carry the virus, William Schaffner, MD, an infectious disease specialist and professor at the Vanderbilt University School of Medicine, told Verywell.
What This Means for Other Viruses
Summer is traditionally not thought of as a time when viruses thrive, but other pathogens can spread in the same way bird flu is spreading in the heat, Schaffner said.
“It’s less about the heat and more about the distribution of the virus through fans and the lack of PPE,” he said.
Schaffner said that COVID could also spread through the use of industrial fans.
“If a worker happened to be infected, there is a potential for infecting a larger group of people because the fans can spread the virus farther distances,” he said.
What Happens Next?
The people infected with bird flu have experienced only mild symptoms and have been offered treatment, according to the CDC.
Both Schaffner and Adalja said there is a risk that this virus will eventually spread between people.
“The current H5N1 bird flu outbreak should be thought of as a trial run, as this virus is constrained in its ability to infect humans,” Adalja said. “But there will be strains in the future that are not so constrained. So, it is important to put in place appropriate countermeasures and to get it right.”
Schaffner said the public health community will continue to monitor the bird flu situation closely.
“So far, so good with bird flu, but we all have our fingers crossed,” he said.
What This Means For You
Since the spring, several cases of bird flu have been reported in humans in the U.S., but all have been limited to people who have been in close contact with infected animals. High temperatures make it difficult to wear personal protective equipment, raising the risk of illness.
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