The bird flu is here and has spread to dairy cows. Does that mean we’re headed for the next pandemic? Not yet.

“Unless you’re someone who is actively involved in raising birds or chickens, or you have close contact with infected cows, it’s unlikely you’ll be exposed,” said Dr. Michelle Barron, veteran pandemic fighter and senior medical director of infection prevention and control for UCHealth


“Animal handlers are usually the most at risk,” said Barron, who is also a professor at the University of Colorado School of Medicine on the Anschutz Medical Campus.

“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 doesn’t necessarily spread beyond that.”

While it’s important to monitor the virus, it’s not yet a threat to humans and shouldn’t take up much brain space.

Barron broke down the basics and answered our burning questions about H5N1.

So, is bird flu new?

No. Unlike COVID-19, this strain of bird flu (H5N1) has been around for about 30 years. So far, only two human cases have been reported since an outbreak of the virus among domestic birds began in 2022, including a Colorado poultry farm worker and a Texas dairy farm worker. Both cases were mild and resulted from direct contact with sick animals.

What’s the big deal about bird flu and its 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 spread to mammals, including dairy cows, cats, dogs, bears, sea lions and more. As of May 2, H5N1 had been found in 36 herds of dairy cows in nine states – among them, a dairy farm in northeastern Colorado.

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.

Does the bird flu affect humans?

Yes, it can.

“There have been a couple documented cases of transmission between birds and humans and cows and humans, but no human-to-human transmission,” 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?

Barron said the risk of spillover to humans is very low right now.

But animal handlers should be careful.

“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. “We’ve seen some cases of bird flu that have spread within the same household in the past but doesn’t necessarily spread beyond that. We don’t get too concerned unless it spreads more widely.”

There have been some documented cases of humans becoming infected with the virus. How has the avian flu affected them?

“Symptoms have been mild. We’ve seen pink eye and some cold-like symptoms,” Barron said.

If symptoms have been so 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? I hear a lot of intermixing happens between bird flus and human flus happens in pigs. Is that true?

“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 this year 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’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?

“Unless you are working directly with animals, there’s really nothing to do,” Barron said. “Follow standard safe cooking practices, and consume pasteurized products. If you are working directly with animals, wash your hands frequently and consider wearing a mask or face shield to prevent splashing.”

Are backyard chickens safer to interact with than chickens on farms?

“In some ways, no,” Barron said. “You can’t stop wild birds, such as ducks and geese, from flying in and out and interacting with chickens. That proximity is always a risk. But on the flipside, backyard chicken operations are smaller, so the conditions and space constraints are different. The higher the volume, the higher the risk.”

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.”

Editor’s Note: The Colorado Times Recorder occasionally posts articles, like this one, from UCHealth Today, which is published by UCHealth, the hospital associated with the University of Colorado School of Medicine. Our goal is to provide as many people as possible with accurate information about medical issues that are poisoned by misinformation, particularly as discussed on social media and talk radio.