Salmonella In Backyard Chickens And Eggs - What's The Real Risk?

Salmonella In Backyard Chickens And Eggs

Recent concern from many of my readers has prompted a response to current Salmonella outbreaks in Victoria, some of which have been linked to backyard chickens. 

There's been a huge surge in backyard chickens, and therefore backyard eggs. It's a timely reminder that foods containing raw egg such as egg based mayonnaise and cake batter can transmit Salmonella to people. Poultry meat is a bigger risk than eggs, but Salmonella can also be carried in manure and in the environment. 

Always wash your hands after any contact with chicken manure, coop cleaning and chicken duties in general, and teach your kids to do the same. There's no need to be frightened of your kids touching the chooks! But it's just basic hygiene. 

I hope to reassure people that with simple food handling and sensible hand washing, you can significantly reduce the chance of you or your family becoming sick with Salmonella. 

While healthy looking chickens can transmit Salmonella, most recent news articles have neglected to say that dirty nesting boxes, (think wet winters!), egg collection and egg storage are a risk when it comes to egg transmission of Salmonella. 

Take note of the good habits below, and you'll enjoy the healthiest, tastiest and most ethically produced eggs possible from your healthy, happy hens. 

What Are The Chances Of Catching Salmonella From My Chickens?

You've probably heard of Salmonella in regards to food poisoning. It can be carried in the environment, in manure, in poultry meat and even eggs. Healthy chickens and sensible hygiene will help keep you safe. There is much less chance of contamination in eggs, but that does not mean there's no chance. 

How can Salmonella spread to people?

Salmonella bacteria may be either on the shell or inside the egg when it is laid. 
1. The yolk becomes infected as the egg is being formed in the body of an infected hen. This risk is very rare, however one of the recent cases backyard cases in Victoria has been linked to a chicken from a commercial egg farm west of Melbourne. The egg farm is now under quarantine and investigation.  
2. Far more commonly, an egg is contaminated by bacteria through the egg shell. This can happen in a number of ways, see how you can reduce this risk below.

The Cuticle - The Egg's Natural Defence

Eggs have a shell (obviously!) but the cuticle is the outer most layer of an egg, and an egg's natural defence against bacteria.

Eggs are laid slightly wet and the cuticle sets as the egg drys. The cuticle is what gives eggs their shine and seals an egg. Poultry Expert, Megg Miller describes it as being like a lacquer - it goes on last, protects and gives the egg its natural shine.

But if eggs are laid into a dirty nest, the cuticle can't protect and do its job.

Also, removing the cuticle through soaking or scrubbing eggs can also increase your risk of Salmonella.

Drawing In Bacteria

Second to that, when an egg is laid, it's warm and slightly wet. But as it cools, its contents contracts like a little sponge and any Salmonella bacteria on the surface of the shell can potentially enter the egg as it cools. So what do you do?

How to reduce the risk of Salmonella in backyard chickens?

1. Keep nesting boxes clean. Do not allow chickens to sleep in nesting boxes.

2. Change nesting box litter regularly.

3. Collect eggs regularly, at least daily. Don't allow them to build up and risk them becoming cracked or dirty. 

3. Separate clean eggs from dirty eggs.

4. Discard cracked and broken eggs instantly. It's not worth the risk.

5. Discard any seriously dirty or soiled eggs. 

6. Don't feed your chicken off or mouldy food, especially expired meats which can be a source of Salmonella.

 How to safely clean eggs for home use with family and friends

1. Never soak dirty eggs in water. Doing so, (cold water is the worst) creates a permeable barrier, ripe for bacteria to enter the egg. 

2. Clean egg by buffing them with a clean abrasive pad. Some small egg farms that don't have an egg washing machine use a block of "Eco Eraser" to scuff the dirt off eggs.

3. A warm, damp, but not soaking, cloth can also be used to wipe eggs, but The NSW Food Authority says "only a thin layer of moisture that can readily evaporate should be visible on the egg surface".  Also use a clean part of the cloth for each egg. 

4. Store your eggs in a clean carton or container. Egg farms are not permitted to re-use egg cartons, as they can harbour bacteria from manure or broken eggs.

5. Don't refrigerate eggs BEFORE cleaning. Again, the egg shell will contract and may pull any dirt or bacteria on the egg surface into the pores when cooled. Egg farms store eggs below 15°C (with 75% humidity) prior to cleaning. We also don't want condensation on the surface of the egg, (which happens when you go from cold storage to warm room) as this can help bacteria cross the shell into the egg. 

6. Refrigerate clean eggs promptly after cleaning. 

I hope this article has been helpful. Enjoy your chooks. The health benefits of keeping chickens far outweigh any health risks. ~Elise McNamara, Chicken Coach.

Other Resources

The Chicken Health Handbook by Gail Damerow

Egg Signals A Practical Guide To Improving Egg Quality

Storey's Guide to Raising Chickens by Gail Damerow

NSW Food Authority

Producing safe eggs at home fact sheet

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