Zoonotic Diseases and Chickens

Have you ever noticed that kids never get sick at the same time?   My youngest is laying like a puddle of water on the couch, recovering from the “gift” my daughter gave him.  We did tell her it is good to share…..

It got me thinking about some of the risks of people getting sick when they get into backyard chickens.  Like most things, the impressions people get from the media are skewed.  The big media scare around chickens is naturally bird flu.  Contagion, Outbreak, and a whole bunch of made-for-TV movies make it seem like we are poised on the brink of a world-wide viral catastrophe.  What makes the stories so engaging is that they are plausible….it truly could happen.  Of course, asteroids could collide with earth,  the magnetic poles could reverse, or a rabid dog could terrorize a small Maine town. 

Bird flu is a concern, but it is a risk that is minimal in North America.  We have never had a bird-human transmissible flu virus on the continent.  If we ever get “bird flu” in Canada, I will bet my next paycheck that it arrives on an airplane, carried by an infected person….likely from a country that is already dealing with a human outbreak.

There are risks with having backyard chickens, however.  Having birds in your backyard means having poop in your backyard, and in your coop.  Having poop in your backyard and coop means you have bacteria in your backyard and coop.  Bacteria will occasionally will make you sick, if you get it in your body.  Salmonella, E.coli, and Clostridium are all types of bacteria that can live in chickens that are a threat to human health.

The nice thing about eggs is that there is only really one bacteria that will contaminate the interior of an egg before it is laid.  Salmonella enteritidis can live in the ovary of the hen, and be incorporated in the egg.  The unfortunate thing is that S.e. doesn’t necessarily make the hen very ill….so you could possibly eat an egg from a contaminated hen without knowing it.  The amount of money and time spent controlling this bacteria by professional farmers is staggering.  We have programs of regular testing, and plans for what to do if the bacteria is ever found….even if we just find it in the environment, and NOT in any eggs.  This makes our commercially available, graded eggs very safe.  In your backyard, it is much more difficult to be sure….  It is expensive and technically difficult to isolate S.e. from a contaminated hen….let alone one who might, or might not have it.  The thing to keep in mind is if anyone in your household, or anyone who eats eggs from your hens, gets sick with diarrhea (especially bloody) or a high fever, PLEASE let your doctor know that you have hens, and eat ungraded eggs…..catching an infection like this early is very important.

The main difference between having chickens and having a dog is that you are planning on eating stuff that comes out of your chicken.  This means that the bacteria in your yard could easily be carried to your kitchen.  Also, bacteria in your yard can get on hands and clothing easily….also adding risk for illness.

As I said above, the only real risk for contaminating the inside of the egg is Salmonella, but eggs come out of the hen moist and warm (>40 C).  That means that if the egg lands in a contaminated spot, it can “suck” bacteria (especially E.coli) through pores in the shell, as it cools.  It is crucial to keep the nest boxes clean, and be very careful with any egg that is not laid in the nest box.  Also, the shell is a very good barrier to infection, but if the egg is cracked, contamination is a much bigger risk.  Once a few bacteria get in through the shell’s defences, it is an ideal spot for the bacteria to thrive, and the number of bacteria will grow exponentially if the conditions are right.

Here is a bit of a checklist to decrease human health risks for urban farmers:

  1. Wash your hands EVERY time you interact with your chickens
  2. Have shoes dedicated to chores time.  Leave them at the back door, and don’t walk through the house with them.
  3. Collect your eggs as soon as practical after they are laid….get your eggs in the morning if possible, ideally before they cool off completely.
  4. Be cautious with how you use eggs any time you have any signs of illness in your flock.
  5. Be careful with any eggs with obvious manure contamination, or have cracks…..look into proper handling of these eggs, or throw them out.
  6. Rinse your eggs in cool, running water after you pick them, then clean your sink with a disinfectant (ie bleach).
  7. Keep your eggs in the refrigerator to keep any bacteria in the egg from reproducing.
  8. Always cook your eggs well to help kill any bacteria that might be present.
  9. Don’t keep your chickens in the house, unless they are in a separate area, with a separate airspace….it is intimate contact with live birds that is a risk factor for influenza transmission from birds to people…..remember, in this situation, you are more likely to make your hens sick, than they are to infect you.

All these steps are simple, straight forward and free, but if you don’t respect the fact that you are producing food, and take the necessary care, the consequences can be significant.

Mike the Chicken Vet


8 responses to “Zoonotic Diseases and Chickens

  1. Pingback: CHICKENS and ZOONOTIC DISEASES ~ RABIES reports from NORTH CAROLINA, RHODE ISLAND, & VIRGINIA ~ CDC Reports: ZOONOTIC DISEASE summary for week ending February 4, 2012. | Natural Unseen Hazards Blog

  2. My flock has had two deaths since we got them as babies last August… the first started being all “hunched up” but not puffy in October .. then being sort of depressed and not moving as much, we brought him in the house to treat him/her and with in hours started gasping and keeled over. No discharge, no other symptoms was eating and drinking fine
    … the OTHER bird, was like the first one, the other RUNT ( both of these were about half the size of the other birds from the day we got them) She was always more easy to pick up, and spent more time alone than with others… she would often, after foraging and running around just sit with her head retracted (but not poofy or wing dropped) Not depressed or slow… just relaxed looking …
    Two days ago we noted she was spending more time alone(but never depressed or sick looking like the other one) and more time :hunched than before… and had started moving her mouth a little like she was gasping, we were about to launch an isolation/medication attack when we went to get her, she was dead … with a little bit of blood dripping out her nostril..
    No discharge, nothing in her mouth…
    One chicken friend suggests ILT but there is no discharge… Another friend suggests since they were both small from birth maybe they both had some genetic or functional problem that caused them to fail to thrive…

    I went out late last night and sat quietly with each bird and examined them.. no weazing, no discharge, no hunching, no gasping… everyone else seems fine… is there anything i can do to make sure this doesnt continue or could this be genetic?
    ( they are a flock of various breeds we ordered from MurrayMcMurray)
    One was a sumatra the other was a partridge rock (we think)
    We are in S Wisconsin and other than this our flock is fine and happy, they range on evenings and weekends when we are home. They get a layer pellet and a bit of scratch for digging when they are in the pen during the day… they get greens we buy in the winter and a variety of kitchen scraps according to the good chicken snack guidelines

    Should we treat with an antibiotic just to be sure?
    Any suggestions will be helpful and appreciated .. thank you!

    • Hi Lisa;

      It is unlikely that the problem is ILT….ILT will affect most of the birds in your flock, and this doesn’t seem to be the case. This is also not genetic….there are thousands of these types of chickens around, and they are not consistently afflicted. Pullet mortality in a 6-8 week old pullet is often the result of a gut infection…either coccidiosis or bacteria. Since it has been months since that single incident, it seems like the rest of your flock is coping well with whatever was around. I don’t recommend treating with antibiotics unless you have a good reason to….if you see loose droppings, more sick birds or some other signs, it might be an option, but treating healthy looking birds with antibiotics only results in antibiotic resistance and less effective treatment options for the future. There is also a concern for antibiotic residues in the eggs, depending on what you use. I suggest keeping a close eye on the flock, and making sure that environmental stresses such as wet areas, cold stress, drafts and dirty environments are minimized….if you decrease the insult level to the bird, they can handle a lot of things on their own, without resorting to antibiotic use.


      • Lisa Carlson

        Thank you, yes, we didnt want to treat blindly as they can lose their affect if over used. It is very wet out lately.. not sure what we can do about that.. but their coop is dry and will keep it as dry as possible…. maybe I could also throw some more hay/.straw down on the ground around the coop as its pretty mucky .. but once they get out they run right thru that to the other areas.. but it will reduce muckiness…


  3. Mary Grace Hansen

    Hi, I have an indoor chicken. Japanese white bantam who was getting walked on when all were babies. So she has been in the house ever since. She is now 30 weeks old. She has a cage and a diaper she wears around the house. Right now she is broody on six eggs from a friend. I can’t have a rooster in the city.
    should I be concerned about her in the house ?
    Disease? there is cleaning the cage and whatever is missed by the diaper. I used to rehab wildlife bunnies and birds. One bird in particular was a runt purple martin with an injury. We had her in the house for sometime.
    But for now just a chicken in the house and dogs.

    • Hi Mary Grace;

      Thanks for the question. The major risk your hen poses for you and your family is from manure, as you seem to be well aware. E. coli, Salmonella and various other bacteria can cause disease in people. If you’ve lived with your hen for 30 weeks, it is likely that there are no dangerous viruses circulating around that might be a problem. I would say that if you are careful to clean up after your hen, you shouldn’t have to worry too much about catching a disease from her.


  4. I thought it was better NOT to rinse your eggs before refrigerating because the “bloom” protects the inside from bacteria? I rinse before using, but I usually just go straight from nest box to refridgerator. Am I doing it wrong?

    • Hi Julie,

      You are right, there is a protein “skin” on the eggshell that helps keep bacteria out of the inside of the egg. And soap and water will remove it….running cool water likely will not. But, even if it does, I think it is a good practice. IF your egg has disease causing bacteria on it (which is not unlikely given the fact that it comes straight out of a nest), and you put it in the fridge, you now have a source of bacteria in the fridge. If you rinse the egg, and eliminate, or mostly eliminate the bacteria…..even if the egg is more susceptible to allowing bacteria inside it, there shouldn’t be a source of bacteria for it to come in contact with.
      That’s just my opinion, however, but it may give you something to think about.


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