Transcript of Mystery over how bird flu spread in cat sanctuary, killing more than half the population

There are new concerns tonight as bird flu continues to spread. A week ago, California declared a state of emergency after a mass infection of dairy cattle there in Washington state, where cases have been on the rise, or that half of the big cats at one wildlife sanctuary died after contracting the virus. Even more concerning, it is unclear exactly how they got bird flu. See that as Randy K. Has the story.

That's Thumper, a 10-year-old Eurasian lynx who used to love to play and scratch the decks high above the foliage. The video from August was taken at the Wild Felid Advocacy Center of Washington, a big cat sanctuary where Thumper lived. Thumper is one of 20 cats from the sanctuary who died in recent weeks from bird flu.

We thought we were doing everything we could to avoid anything like this from happening. The cats are pretty well split up into 30 by 40-foot habitats.

The sanctuary's director and co founder, Eric Matthews says the cat's enclosures are spread out among five acres. He told me their first cat got sick on November 22nd. The 17-year-old cougar named Hannah Wyoming stopped eating and died the next day. A day later, this African and Caracal, named Crackle, also got sick and died. Others they lost included this cougar named Holly, and Tabby, a bangle tiger.

Tabby, the tiger, was a very fun, loving tiger. She had a super personal personality. Every time I came up, she'd come running to meet me.

This bangle cat, Pebbles, also succumbed to bird flu, as well as Mouse, a Jeffrey cat. Only 17 of the 37 cats once housed here are left. Nico, an African serval, is still in critical condition, fighting to regain the use of his back legs.

Feeling devastated, in shock. Just taking really good care of those ones who are recovering.

The disease read rapidly, and they still don't know how exactly the bird flu entered their facility.

Initially, we thought it was the bird droppings from waterfowel. We are in a flight pattern for migratory birds, so I don't know if that's part of the equation or not. We really don't know at this time if it was food related or not.

Although we don't know exactly how it got there, it just makes sense that it's likely due to migratory birds because we know bird flu is transmitted through the migratory bird population.

Dr. Dean Blumberg is an infectious disease expert at UC Davis.

It's spread through the bird's saliva, the feces, the urine, and so you really can't protect against that in the natural environment.

The staff at the sanctuary are working tirelessly to disinfect the habitats while also protecting themselves from getting sick. They're wearing PPE, including N95 masks, and doing foot baths when they enter and leave.

The virus may mutate and become more easily transmitted person to person. So the more this virus circulates and specifically co-circulates with human strains, that's going to increase the odds of the virus evolving to more human-to-human transmission. And that, of course, could signal another pandemic.

Randy, I understand there's also concern now about house cats. What are you learning?

Yeah, Jim, there's not only the big cats who are at risk, but now it seems that the house cats are at risk as well. This is after a house cat in Oregon died after eating a pet product that was later found to be infected with or tested positive for bird flu. So now this Portland, Oregon based pet food company is issuing a nationwide voluntary recall. The name of the company is Northwest Naturals, and the recall is for a two pound feline turkey recipe. That's one of their raw frozen recipes. And I should note that this product was distributed all over the United States. Across this country. It was also distributed in parts of Canada, including British Columbia. So there's a lot of concern, Jim, for pet owners, certainly cat owners, about how this might spread. Can their cat get it? Can it spread to humans? So many questions for pet owners. I also want to note, Jim, that that sanctuary we reported on is closed for now to the public, but they are hoping to reopen again in March.

Randy Kay, thanks so much. Joining me now, Director for to the Center for Infectious Disease Research and Policy at the University of Minnesota, the epidemiologist, Michael Osterholme. Good to speak to you again, sir. Thanks so much for joining.

Thank you, Jim. Good to be with you.

As far as we know, at this point, bird flu has not made the jump of going from human to human. People have contracted the virus from animals. I wonder how far away we are from that possibility. Are we just, in effect, one mutation away from human to human transmission?

Well, Jim, let me just be really clear here that this is not rocket science, this is flu work. It's actually a lot more complicated. We don't know. Anyone that tells you they do know, you have to be very careful. What we do know is, of course, flu viruses continue to change. They mutate. This particular H5N1 virus has been doing this really since 1996 when it first showed up. China caused an outbreak in Hong Kong in '97. What most people don't realize is this was killing cats way back in 2003 and 2004. One of the zoos in Thailand lost over 100 large cats because they were fed culled poultry that had died from H5N1. We've been seeing this for a long time in cats. What's changed, though, is in the last two years, a new strain of this H5N1 has emerged that has caused a lot of additional infections in mammalspecies that we'd not seen this before, over 50. And of course, as you're well aware, the dairy side of the house now has also contributed substantially to this, which we had never seen before. So we don't know where we're at right now with this virus.

There will be more influenza pandemics. Is this the one that's going to cause it? We don't know.

That's the open question, of course. I wonder, and I remember, I've covered previous H1N1 outbreaks years ago. Those did not develop into a pandemic, thankfully. I wonder, over what time period might such a thing happen And given where we are now? Is it a matter of weeks, months, years, or does that fall into the we don't know category as well?

We don't know category is really the operative word for today. But let me just point out that we are doing more and more with this virus as a result of human activity, such as what we're seeing in dairy cattle right now, bringing together this virus. And we only learned this past year that the cow udder actually has receptor sites or the ability for both bird viruses and human viruses to grow in that udder. Why is that important? Because that's how you actually see pandemic strains emerge, where two different viruses co-infect cells, swap out genes, and then create this brand new virus. And so this is why we're so concerned. Has it happened yet? No. We have not seen any evidence of severe illness being transmitted to individuals who work in the dairy area. But that could all change tonight. And that's what we're trying to help people understand is that we're on a major alert right now for this issue.

What should the country country be doing right now to help, to the extent that it can, to help prevent this from becoming something more serious?

Well, this is a lot like going off the edge of a cliff. It's really pretty safe until you get to that last 100th of an inch and then you go off quickly. And that's where we're at right now with this virus. We don't know if we're ever going to get to the edge of the cliff. There is not a lot that people can do as individual citizens. What we need to do is do much more to try to bring the H5N1 situation and dairy cattle under control. We're almost at 900 herds now in this country, infected, of which 75 % are in California, and it's just continuing to spread. Remember, I just mentioned that issue about the cow udder and how that could serve as the melding pot for developing a new flu virus. It's unacceptable that we continue to see this transmission in these cattle. Much more needs to be done there. We need to be doing more with vaccines. There was a release today from the CDC looking at this case of illness that occurred in the woman in Louisiana. The good news is that this particular virus looks like it matches up with a candidate virus we have for a vaccine.

The problem is there's not one drop of that vaccine made yet. And the world only has the capacity to make about 3.5 billion doses a year, and that's it.

And it's happening at a time when there's vaccine skepticism, despite the enormous successes they've had. Exactly. With a number of diseases. Michael Osterholme, thanks so much, as always.