When bird flu first struck dairy cattle in Texas last year, it was unclear how the virus might spread.
As of now, H5N1 has infected more than 900 herds and dozens of people, killing one person. The outbreak shows no signs of abating, and although experts say a human pandemic is not inevitable, a series of developments over the past few weeks indicates that it’s no longer just a remote possibility.
Dr. Catherine Troisi, a professor of epidemiology at UT Health Houston School of Public Health, said there’s been 67 cases of bird flu in people.
“We have had one case in Texas, which was last March. I have not seen any since then. But of course, it’s always dependent on testing,” she said. “If you don’t test for it, you won’t find it. And also, we do have some information that some of the infections can be asymptomatic. So we don’t even know if people are infected.
“The good news is, if it’s asymptomatic, they aren’t real sick. But that’s another caveat. So it’s been seen in a variety of states and in Canada and in the U.K. as well. So, you know, it is spreading, luckily, not real fast.”
Most of the cases in people came from contact with infected dairy cows or poultry, Troisi said.
“There does not seem to be sustained human-to-human transmission. But of course, that’s what we’re always looking for. Influenza viruses can change very easily, and right now it’s not infecting people very easily, and it’s with mild symptoms,” she said. “Most of the cases have been conjunctivitis. However, the virus can change, and the big worry is that it will adapt and infect humans easier and perhaps become more serious than just conjunctivitis and spread person to person.
“And because this is a virus we haven’t seen before, most people, well, everybody is not going to have antibodies. You actually might have a little teeny bit of immunity from seasonal influenza, but basically it’s going to be like a new virus. And that can be serious.”
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Troisi said there is no way to know if the virus will mutate and cause a human pandemic.
“We do know that every time the virus replicates more of itself, there’s a possibility that that mutation will occur. So what’s scary right now is because we see so many infected cattle, so many poultry flocks that are infected, that’s a lot of virus replication going on,” she said. “The other place we’ve seen it is in cats, either from drinking raw milk – because raw milk from an infected cow can contain the virus – or from cats that go outside and catch wild birds.”
It is also possible for people to get infected from contact with a sick cat, Troisi said.
The situation with the virus is somewhat complicated by the fact that the Trump administration has ordered federal health agencies like the CDC to pause public communications.
“There’s still information about avian influenza on the CDC website. So if you want to find out where cases have been found up till last week – but I don’t know whether there’s been any new ones since then; that’s the kind of information that would be missing – but if you want to find out how to protect yourself where we’ve seen it again up to last week, what mammals have gotten infected, etc., that you can find out on the CDC website,” she said. “You can get information from your state health department.”
Troisi also recommended people look at the Texas Epidemic Public Health Institute, which is housed at UT Houston School of Public Health.
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Troisi said, for the moment at least, the embargo of information from the CDC is more serious for researchers and public health practitioners than it is for everyday people. She said there are a number of infectious diseases circulating this winter season that are harder to track without new information from the federal government.
“We’re in the middle of a lot of cases of seasonal influenza, Respiratory Syncytial Virus, we are seeing COVID 19 infections. And then a lot of norovirus, the virus that causes GI symptoms,” she said. “It’s particularly important for public health officials to know what’s happening in their community.
“And if the CDC surveillance programs are not sharing information that they found, that can be serious. Hopefully this won’t last for very long and we’ll start getting information again. But, you know, right now we’re sort of blind about what’s happening.”
For those who want to keep themselves safe from bird flu, Troisi said masking in crowded places and avoiding raw milk are two good ways to stay healthy.
“It is not a good idea for a variety of reasons to feed raw milk to your cats. It’s also not great for people either. And again, it’s not just avian influenza. There are other bacteria that can be in raw milk that pasteurization will kill,” she said. “If you are at a high risk for a serious outcome should you get infected – which is older age, underlying conditions — and you’re concerned, go ahead and wear a mask when you’re in a crowded condition. It doesn’t hurt and might protect you from flu and RSV and COVID, even if avian influenza isn’t around.”
