Several cases of “bird flu” have been detected in North Carolina and other eastern states. But what exactly is bird flu? Why is it important? Does it affect humans? What can we do about it?
To answer all of these questions, we reached out to Matt Koci, a virologist and immunologist whose work focuses on host-microbe interactions in birds. Koci is a professor in NC State’s Prestage Department of Poultry Science.
The Abstract: When people refer to “bird flu,” what exactly are they referring to?
Matt Koci: “Bird flu,” sometimes called “avian flu” or “avian influenza,” is essentially the slang term the media uses to differentiate influenza viruses in birds from seasonal flu viruses in people.
It can be a confusing term because there are a lot more types of influenza viruses that infect birds than there are types of influenza that infect people. This term can be used to refer to any one of over 140 different virus subtypes of the virus in birds. However, it’s mostly used to refer to a handful of influenza virus subtypes that cause severe disease in chickens and turkeys. These viruses are also called highly pathogenic avian influenza viruses.
TA: So, it crosses over from birds into people?
Koci: Yes and no. Sometimes. Did I mention it’s complicated?
The vast majority of avian influenza viruses do not make people sick, even most of the ones that have high mortality rates in poultry.
There are just a handful of bird flu viruses that have infected people. Over the past 20 or so years we’ve seen less than 2,000 total infections in people worldwide. That number is low because, while a few of these viruses have managed to infect some people, they don’t spread from person to person. So, the risk of getting infected is only for those who are around, or work with, poultry that are infected with these viruses.
That’s not to say scientists don’t take them seriously. We do. Just under 40% of the people infected with bird flu have died. And just because they haven’t figured out how to spread from person to person yet, doesn’t mean someday, Mother Nature won’t spit out a version of bird flu that can. So, there is a lot of effort around the world to monitor and study these viruses.
TA: Is it dangerous?
Koci: It’s certainly dangerous if you’re a chicken or turkey. But the real danger this virus poses to North Carolina is our economy. It would be devastating if it got into commercial poultry in N.C. Poultry production in N.C. brings in over $4.7 billion, and that’s just from farm sales. When you factor in all the jobs around poultry production, processing, cooking, and consuming, the economic impact of poultry goes up to around $40 billion.
And it’s not just dollars and cents. N.C. accounts for about 12% of all the poultry production in the United States. If you think grocery store shelves are sparse now, just think how much worse that could get if we lost 12% of the poultry meat and eggs in the U.S.
That’s why the U.S. Department of Agriculture and the N.C. Department of Agriculture (NCDA) are asking people with backyard and free-range birds in N.C. to move them indoors and keep them away from migratory birds. This is always a good idea to limit their exposure to diseases, but it’s especially critical right now.
But I think your question was more geared toward is this dangerous to people. As in, can bird flu infect people? The honest answer right now is we don’t know. There is no evidence that the virus found in wild birds in N.C. is one that might be able to infect humans, but that doesn’t mean that it can’t. It could just be it hasn’t had the chance yet. Again, this is another reason why the USDA and NCDA are encouraging people to bring their birds indoors: to limit the chances it gets to try and make the jump.
If it can jump, the people at greatest risk are those who raise poultry, either as pets or for food. They will be the proverbial canary in this coal mine. If you raise poultry, especially if they are kept outside, you need to do all you can to keep your birds from getting infected. And if, in spite of your best efforts, they still end up getting infected, you need to know what to look for. The NCDA has a good summary of disease signs in poultry.
If you suspect your birds have it, you need to call a veterinarian. Handle it like the highly contagious virus it is: use gloves, masks and a lot of disinfectant. And don’t try to nurse them back to health. It may sound funny to some, but that’s how a lot of people in other countries have contracted bird flu and died.
Once thing I can’t stress enough though: there is zero risk of getting bird flu from eating poultry products. First, no commercial poultry in N.C., or the U.S. for that matter, has bird flu. If any farms do end up getting bird flu, those birds will not enter the food supply.
TA: How does it spread? And what can we do to reduce our risk of contracting it?
Koci: So this particular virus appears to spread, so far, via migratory birds. For reasons that still aren’t clear, while these viruses are deadly to chickens and turkeys, they don’t make ducks or other migratory waterfowl sick. These birds are able to carry the virus asymptomatically. As they migrate they literally poop out the virus. If that poop lands in a yard or pasture where poultry are out foraging, they can get exposed to the virus. In some cases, which is what we think happened in Canada, migrating birds land in ponds on a property and comingle with the poultry and spread it to the domestic birds that way. In fact, your birds and the wild birds don’t ever have to come in contact. The wild birds can contaminate the pond water and your birds can then get the virus from the pond after the wild birds have moved on.
Once it’s in domestic birds, it can get spread from place to place by people. Some bird poop gets on your boots at one place, you go over to your neighbors to look at what they have going on and carry the virus with you.
There’s even a risk that people, especially hunters, could be the link between wild birds and domestic birds. Hunters who handle infected ducks, or even just stomp through ponds where these birds have been, can carry the virus back to birds on their property.
TA: Are there particular things that people who own chickens or other poultry should do?
Koci: Yes, I’ll refer back to the NCDA page. They have good information and are keeping things updated. If you have poultry, and they are allowed outside, keep them indoors as much as possible for the next month or so. On top of that, reviewing your biosecurity practices (see the NCDA page!) to make sure you’re doing all you can to keep from tracking it in from other places. Make sure you know what to look for, and who to call in your area if you think your birds might have it.
TA: Do we know how this virus got to North Carolina? Does that even matter?
Koci: So far, the reports of it are just in wild birds. They were discovered because of increased surveillance that happens this time of year due to the southern migration of wild birds – and because of multiple reports of birds in Canada being infected with bird flu. So the assumption, but probably a pretty safe assumption at this point, is that bird flu arrived in N.C. via migratory birds. Hopefully, the migratory birds will keep it to themselves and, as they move further south it will go on with them. Time will tell.
This post was originally published in NC State News.