Avian Influenza Again

Some of you might be aware that there is another outbreak of Avian Influenza in Canada. In British Columbia, on our west coast, a total of 10 barns have been found to be infected (so far). I’m getting quite a few calls asking about information around the disease, so I thought I would share some thoughts with you, in case you are interested.

Avian Influenza (AI) is a virus that is pretty well adapted to ducks and geese. The bug lives in fairly good harmony with waterfowl, not causing too much disease or problems. Then….it gets into chickens (or turkeys). AI gets into cells in the windpipes and lungs, making the birds sick….but not too sick. The virus hijacks the birds cells to make copies of itself, and then destroys the cell, and spread the new viruses into the world. This is what we refer to as “Low pathogenic” AI. Chickens and turkeys don’t feel well, but the severity is a lot like a cold for us…farmers would notice the flock was off, but no alarm bells.

Then….a couple subtle changes happen in the virus, and the bug becomes able to penetrate cells in the windpipes and lungs, but also the intestines, muscles and some other organs. The virus makes many more copies of itself each time it invades a cell, and it invades A LOT more cells. As you can imagine, the amount of virus produced is staggering, and the number of cells damaged by the virus are very high. The virus now has become “Highly pathogenic”. It makes birds desperately ill or dead extremely quickly. So quickly, in fact, that they don’t even seem to be sick….you can check the birds in the barn at 9 am, and notice nothing….come back at noon, and hundreds of birds are dead…..call the vet, who gets there at 3pm, and thousands of birds have died….it’s that fast and that severe. In the current outbreak, over half the turkeys in one flock had died within a day and a half from when they first got sick.

The other aspect of AI is that it is so transmissible that it sometimes seems like magic. It rides the wind, lives in water, can attach itself to clothes, tires, shovels, manure spreaders…..anything. In one outbreak I was involved with in the 90s, a backhoe was used to dig the hole to bury an affected flock for disposal. The backhoe was washed, and trailered 30 miles back to the owner’s lot. It was parked about 200 yards upwind from another barn, and that barn got infected. Controlling this disease is extremely difficult, and trying not to spread the virus while trying to stop the outbreak is tricky.

There are a small army of really smart people doing heroic amounts of work, trying to stop the spread of this disease. Birds can’t move without a permit showing that the flock has tested negative. Feed is delivered in very precise way, in a determined schedule. Affected flocks are quarantined, and euthanized, and any flock within the safety zone (usually 1-3km around the affected flock) is immediately tested. I am REALLY glad I’m not involved in the clean up, and commend all the farmers, vets, government officials and all the other people involved in the clean up.

You might ask what the human risk is. The risk for human infection is extremely low. Very, very few Influenza viruses can transfer from birds to mammals, let alone people. Also, the only risk to people at all, is through contact with infected live birds, or their environment. If you are not exposed to sick birds, or involved in the clean-up, you cannot get influenza from eggs, chicken meat, or any chicken product. I have no more fear of a human pandemic from this outbreak than I fear California falling into the ocean because of a massive earthquake…..both are imaginable, but vanishingly unlikely.

I hope this helps answer any questions you might have had, and if you would like to know something else, please ask.

Mike the Chicken Vet

9 responses to “Avian Influenza Again

  1. Good article. Interesting. How common is it in backyard flocks? And/or what is its history in that category or hen keeping? Aside from careful biosecurity what else can be done to prevent AI?

    • Hi Jennifer. AI occurs in backyard flocks….probably more than commercial flocks, since backyard birds are often outside, and more at risk of exposure. It isn’t often diagnosed, however. If you have 5 hens, and go out and find them all dead in the morning, would you submit them to a lab? of course not…you’d suspect bad feed, or something catastrophe. so it is under diagnosed, but I don’t know by how much….it is still (thankfully) a very rare disease. there is really nothing beyond bio security that can be done to prevent it.

  2. If a backyard flock tests positive for AI and the flock is culled, how long of a time period must pass before a new flock can be brought in and not catch the virus? What can be used to disinfect/sterilize the area where an AI flock was kept to make it safe for future birds?

    • Hi Maria, if a flock is euthanized for AI, there is extensive cleaning disinfection and disposal that is mandated by law. This includes extensive testing by the government agencies. Once the entire quarantine zone is free of the virus for 60 days, birds can be brought back into the area. After the zone is clear, disinfection is not an issue, other than trying to keep general bio security in place.


  3. Thank you for the article Dr. Mike. Just breaking is that AI has been found in birds in Washington state and in backyard poultry flocks in Oregon. For backyard flocks, how at risk are we that the government will demand a flock be culled? Can or have they done this if it is in the area or do you have to have AI diagnosed in the flock? I am in CA. Thanks,

    • Hi Marci,

      Yes, if a backyard flock tests positive for avian influenza, they will be subject to depopulation, same as a commercial flock. Also, you have to allow inspectors to test your birds, by law. It is a nasty business for everyone involved.


  4. Hi Mike the Chicken Vet! Say, I was wondering if I could ask about another issue my chickens have had, and one of them currently is sickly with the same issue, but I can’t find any way to contact you.

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