It’s been one year since scientists discovered bird flu in dairy cows in Texas.
This strain of flu has decimated both wild and domestic bird populations for years. But its leap into cattle signaled a new phase for the virus. Shortly thereafter, dairy workers were found to have contracted the same strain. It also affected cats near the dairy, and a number of other species of animals.
Earlier this week, the British government confirmed that researchers identified the first sheep with avian flu.
Epidemiologists are doing their best to track and predict the virus’ spread, including Gregory Gray, professor in infectious disease epidemiology at the University of Texas – Medical Branch in Galveston. He spoke to the Texas Standard about the current risk to humans.
This transcript has been edited lightly for clarity:
Texas Standard: How would you characterize this current trajectory of the bird flu’s transmission? What’s going on?
Gregory Gray: Well, the strains that are circulating now in North America are very different, and they have not only rapidly spread in wild birds, but we’ve seen some very unusual transmission to many different types of mammals, and then most recently livestock, so it’s very odd.
Very odd in what way? Because of the transmission to livestock or because of something else?
Well, it’s odd in the sense that there’s been so many spillovers to new species, so the viruses have adapted characteristics that make that possible. And we just haven’t seen that since the 1930s, I guess, when we first understood influenza viruses.
I’m having a little bit of difficulty understanding how this would pop up in the U.K. Is it related to the strain that we’re seeing in the U.S.?
I’m not quite sure about those strains, and those data are very new regarding the spread to the sheep. But through many parts of the world, there are certain groups of these viruses that have become prevalent and show the propensity to spill over to new species.
» GET MORE NEWS FROM AROUND THE STATE: Sign up for Texas Standard’s weekly newsletters
What sort of risk does the virus pose by mutating like this?
Well, there’s the possibility that if multiple characteristics in the genome and multiple gene segments acquire increased markers for severe disease and markers for transmission within humans, between humans, then we’re in trouble.
How does this seem to be transmitting? Through breath? Through the air? What exactly?
Well, the transmission that we’ve seen recently in avian species, as well as in livestock, particularly cattle, it seems to have been through different mechanisms – and sometimes that’s been, for the birds, oral fecal transmission. So one bird species gets in contact with fecal material of another.
In the cattle, how that moved from the birds to the cattle we don’t fully know, but there seems to be transmission within the cattle through several different means, primarily through milking and maybe secondarily through some respiratory. But we don’t fully understand it all, and especially we don’t understand how it jumps from farm to farm.
How concerned should everyday folks be about this mutating and becoming a major issue for humans?
Well, I think it’s something to be concerned about, but I wouldn’t panic just yet. I think what’s happening is we need to keep a pulse on this and monitor the strains that are moving between species and the outbreaks, if you will, that are occurring in livestock, make sure they haven’t adapted the characteristics that would make them highly transmissible to humans.
And particularly if we digest food products, whether they be poultry, eggs or milk, as long as those products are cared for in the expected ways – proper cooking and heating with pasteurization – we’re very safe.
If you ingest raw milk products or raw cheese products, that’s a different story. You could put yourself at risk.
