By Katie Kerwin McCrimmon and Kelly Ragan
People who keep backyard chickens should be on guard since the bird flu now has spread from infected chickens to people, with one Wyoming woman requiring hospitalization, according to Wyoming health officials.
The avian flu also has caused agonizing deaths in indoor cats. In Michigan, health officials suspect that infected dairy workers contracted avian flu, which then spread to domestic cats and killed them.
Here’s the latest news on the spread of avian flu, which is also known as H5N1:
- Health officials in Louisiana have documented one death in a person from avian flu. The patient had underlying medical conditions and was over age 65. The patient contracted H5N1 after exposure to a combination of both “non-commercial backyard birds and wild birds.”
- A woman from Platte County, Wyoming had to be hospitalized after she got bird flu from infected backyard chickens. Wyoming health officials said the woman had underlying health conditions that made her vulnerable to severe illness from H5N1.
- Along with people who have backyard chickens, cat owners should be on guard. Cats that spend time outdoors can eat infected birds while indoor cats could be infected through raw food or contact with infected humans.
- The bird flu continues to spread in dairy cattle and in people who work with cows. Some of the people who have tested positive for H5N1 have not had obvious symptoms. While health officials say it’s good that the bird flu doesn’t appear to be causing severe illness in most people, subtle symptoms may make it easier for the disease to spread undetected.
- So far, U.S. health officials have not detected human to human transmission of bird flu, but it appears to be spreading widely among cows and has infected people who care for cows.
To learn more about the bird flu and to get answers to your top questions, we spoke with Dr. Michelle Barron, senior medical director of infection prevention and control for UCHealth and a professor of medicine and infectious diseases at the University of Colorado School of Medicine on the Anschutz Medical Campus.
For now, Barron said most people do not need to worry about getting the bird flu, and since there’s not yet evidence of human-to-human contact, there’s no immediate danger of a new bird flu pandemic.
Still, Barron and other infectious disease experts in the U.S. and around the world are keeping a close watch on H5N1.
How concerned should I be about avian flu if I have backyard chickens?
Barron is warning people with backyard chickens and those who work closely with animals to be on guard.
“If you work in the agricultural industry where you have contact with animals, you need to be careful. And if you have backyard chickens, and you have a sudden die-off of your chickens, you need to be very careful. Do not handle the chickens. Call the health department and get them tested,” Barron said.
“If you have backyard chickens, it’s possible to get the avian flu. I would be thoughtful about how you manage them. Do not handle them without gloves,” Barron said.
When infected birds poop, the virus that causes avian flu can aerosolize — meaning it spreads in the air. That’s why it’s so easy for bird flu to spread within flocks.
“They’re all together, and they poop all the time,” Barron said.
She advises people to be very careful if they have chickens or work with birds.
“Do not handle a sick bird without gloves, a mask and protective gear. If you’re managing animals of any kind, it’s a good idea to use protection for the eyes and mouth.”
People need to clean pens and chicken coops well. Learn more from experts at the U.S. Centers for Disease Control and Prevention (CDC) about how to prevent the spread of avian flu if you have chickens.
What if I have cats? How can I protect my cats from bird flu?
“There have been reports of avian flu in mice, rats and cats. The cats got terrible neurological symptoms and died,” Barron said. “The flu can cause issues in the brain. It’s not unheard of in humans.”
House cats can be exposed to avian flu through infected birds or if they eat raw food. Barron would avoid feeding cats raw food and advises humans not to eat raw eggs or unpasteurized milk.
“I would avoid eating raw eggs mainly because of salmonella,” she said.
But it’s possible for raw foods to also be sources of contamination for the bird flu.
Who is most at risk for getting bird flu now?
“Animal handlers are most at risk,” said Barron.
“We don’t get too worried about spillover unless we see prolonged human-to-human transmission,” she said. “We’ve seen some cases of bird flu that have spread within the same household but don’t necessarily spread beyond that.”
So, is bird flu new?
No. Unlike COVID-19, this strain of bird flu, H5N1, has been around for about 30 years.
What’s the big deal about bird flu and the spread to cows?
While the virus has been around for a while, an outbreak that began in 2022 among birds has killed about 90 million domestic birds in the United States. If you paid north of $7 for a carton of eggs in 2023, this outbreak impacted your wallet. Egg prices in Colorado skyrocketed in early 2023 after an outbreak, dubbed “the worst-ever” resulted in the deaths of more than 6 million chickens between infections and culling efforts to reduce spread. This is the longest and deadliest outbreak of H5N1 in history, according to Barron’s colleagues at the University of Colorado School of Medicine.
The virus is making headlines again because it has spread to mammals, including dairy cows, cats, dogs, bears, sea lions and more.
The jump to mammals has experts watching closely, as the change gives the virus an opportunity to figure out how to replicate more efficiently in mammalian species.
What exactly is avian influenza?
“It’s bird flu, which is different from human flus or pig flus,” Barron said. “Animals can get the flu just like we do. The thing we know about this bird flu is that it mostly affects chickens, causing respiratory symptoms.”
Sometimes bird flu is referred to as a ‘highly pathogenic avian influenza.’ What does that mean?
“Highly pathogenic speaks to the mortality piece and the ability to cause severe disease. A highly pathogenic avian flu virus has a high rate of transmission and a high mortality rate in birds,” Barron said.
So far, there have been reports of the avian flu infecting cows, dogs and cats in addition to birds. How did those animals get infected?
Any animal has the potential to get infected. It’s just unclear how effective the virus will be, Barron said.
When a virus jumps from one species to another, that’s often called a spillover event. What is the risk of ‘spillover’ to humans?
People who work around animals need to be wary of spillover from animals, Barron said.
“Good protection measures include using gloves, masks and eye protection if you do have close contact with animals, but I imagine it can be a messy job, so that might not always be possible,” Barron said.
How has the avian flu affected humans?
“Symptoms have been mild in most people,” Barron said. “We’ve seen pink eye and some cold-like symptoms.”
Milder symptoms and asymptomatic cases of bird flu in humans don’t surprise Barron.
“It means that if people had contact with H5N1, their immune systems saw it and got rid of it,” Barron said.
That’s good for individuals. For epidemiologists, it can be difficult to track a disease if people have only mild symptoms and don’t get tested,” she said.
If symptoms in humans have been mild, why is everyone so worried about bird flu?
“There’s the potential for that to change, which makes everybody so nervous. Flu viruses can mix together and exchange genetics so pieces of a bird flu can get into a human flu, making the virus more transmissible to humans. That’s how pandemics often happen – pieces of an animal flu get into human flus, and we don’t have immunity to that new virus,” she said.
What about pigs? Does the intermixing between bird flu and human flu also happen in pigs?
“That’s exactly right,” Barron said. “Pigs have receptors for bird flus, pig flus and human flus. The viruses don’t necessarily make them sick, but they can hang out in the pigs’ respiratory systems and intermix. That’s where some of the genetic exchange can happen. That’s what happened in 2009 with the H1N1 swine flu pandemic.”
Avian flu fragments have been found in milk. Is milk safe to drink?
“Yes, pasteurized milk is safe to drink. The heating effects of the pasteurization process will kill the virus, and the virus fragments are not dangerous,” Barron said.
What about raw milk?
There was a bill in the legislature that would have made raw milk more widely available. It ended up dying in the Senate, but raw milk is still available through herd share programs.
“Some believe raw milk has health benefits. I’m in favor of pasteurization because of what I do,” Barron said. “I see what happens when people eat raw cheeses and drink raw milk. I’m more worried about listeria, but bird flu is on that list now as well. The average person at the grocery store won’t be encountering raw milk because it isn’t sold there, although they may find some unpasteurized cheese.”
What other bird flu pandemics have we had in the past?
“Flu pandemics do occur every 20 years or so, the last one being swine flu in 2009,” Barron said. “When we get flu shots every year, we’re protecting against what we call ‘antigenic drift.’ I like to tell people that it’s like if you have to write something over and over again on a chalkboard, by the time you’re writing it the 20th time, there may be a spelling error.
“That spelling error gets copied, and the original word eventually doesn’t look the same. A pandemic is more likely to happen when there is an ‘antigenic shift.”’
“That’s when we have the human flu viruses mixed with the animal flu viruses that produce something our immune system doesn’t have protection against. There have been other bird flu pandemics, including the 1997 H5N1 strain, the 1970s H1N1 flu strain, the 1968 H3N2 flu strain, and of course the 1918 H1N1 flu strain.
So, bird flu pandemics aren’t always as big as the 1918 pandemic?
“Right. It doesn’t always have to be extremely deadly. I think that’s something people assume. If you get this, you’re going to die. And that’s not necessarily true,” Barron said. “The term ‘pandemic’ doesn’t necessarily reflect the severity of the illness. It just means you have a susceptible group of people, and the virus can spread.”
What precautions should people be taking?
Health experts with the CDC advise people to take the following precautions:
- Avoid direct contact with sick or dead wild birds, poultry, and other animals.
- If you must have direct contact with sick or dead wild birds, poultry, or other animals, wear recommended personal protective equipment and be careful. Wild birds can be infected with bird flu even if they don’t look sick.
- Do not touch surfaces or materials like animal bedding without protection since it can be contaminated with saliva, mucous, or animal feces from wild or domestic birds.
- Do not touch or consume raw milk or raw milk products, especially from animals with confirmed or suspected bird flu.
“Follow standard safe cooking practices, and consume pasteurized products,” Barron said. “If you are working directly with animals, wash your hands frequently and consider wearing a mask or face shield to prevent splashing.”
What kind of treatments are available if people do get sick?
“We have some antivirals that work against human flus,” Barron said. “I don’t know if they would have the same effect against this bird flu strain. My suspicion is they would. But so far, the cases have been mild and really just call for observation and treating the symptoms as opposed to treating the disease.”
“At this point, it’s a completely different situation,” Barron said. “I think the main lesson is to be vigilant in our surveillance and paying attention to these smaller outbreaks.
“I think the communication piece has also changed. We’re making sure to get that information out there early so there aren’t all these conspiracy theories or information that is just wrong. Even if we don’t know everything, we’re communicating better about what we do know,” she said.
Should we be stocking up on N95 masks and hand sanitizer?
“So, this is my personal bias and a professional hazard. I think you should always have hand sanitizer around because hands transmit so many infections,” Barron said. “But beyond that, no, I don’t think so. It’s good to be prepared for emergencies, but there’s no need to stockpile.”