Salmonella in Eggs: It’s Poisonal

I recently had an email conversation with Rick, a reader who got in touch via the “Contact Me” button (parenthetical comment to readers, “That button really works! Who knew?”) to ask about salmonella in eggs and specifically the difference between eggs in the US and the UK.  As I was writing my reply to Rick, it occurred to me that while I’ve touched on the subject of salmonella in eggs in a number of posts, perhaps an entire post on that specific topic would be useful. So here it is!

 Salmonella Makes You Sick – And It’s Out There!
First of all, salmonella continues to contaminate a lot of food.  According to CDC, salmonella “causes about 1.2 million illnesses, 23,000 hospitalizations, and 450 deaths in the United States every year.”  A few months into 2019 there have already been significant salmonella outbreaks in cut melon, ground turkey, and frozen raw tuna.  And eggs continue to be a problem:  In April of last year, Rose Acre Farms, the second largest egg producer in the US recalled 206,749,248 eggs, and on April 16, Cal-Maine Foods, the largest egg producer in the US recalled 23,400 dozen eggs which it had purchased from Rose Acre Farms, after they were linked to a salmonella outbreak that infected forty-five people in ten states.

 Secondly, and very importantly, the real scoop on salmonella is that it lives in animal intestines.  When somebody comes in contact with salmonella they’re actually coming in contact with the intestinal contents of an animal.  “Intestinal contents” you probably know, is another word for poop.  It’s hard to avoid poop—it’s everywhere.  As Stanford microbiologist Stanley Falkow famously put it, “The world is covered in a fine patina of feces.” So, salmonella-contaminated meat came in contact with animal poop—probably during the slaughter/butchering process.  Fruit and vegetables contaminated with salmonella either got slimed directly or perhaps were washed in water that had poop in it.  Or somebody made their salad on their kitchen counter right after they cut up their raw poop-contaminated chicken.  Keep in mind that it doesn’t take much salmonella to make you sick.

 And then there are eggs.  Nature provided chickens with only one hole (it’s called a vent or cloaca) and everything entering the world from the chicken enters through the same hole.  Fortunately, it’s a very well-engineered hole, so eggs and bodily waste can’t pass through at the same time.  But you can see that eggs have a potential to become contaminated.  Fortunately again, the egg is well designed – while the eggshell is naturally porous, the outside is coated with a natural varnish called “bloom” or “cuticle” that prevents salmonella or anything else from entering the egg. (I’ve written in greater detail about eggshells here.)  With eggs, salmonella may be on the outside of the shell in chicken poop, or because of the way chickens are anatomically put together, the salmonella may enter the chicken’s egg-producing organs and be inside the egg, because the egg formed around it.

 Naturally, responsible governments don’t want their citizens to get sick from eating salmonella-contaminated eggs, so they have taken risk-reducing steps and passed laws regulating how chickens and eggs are dealt with.  Interestingly, the methods the US has chosen are so very different from the methods used in the UK and the much of the rest of Europe that eggs produced in the US can’t legally be sold in Europe and vice versa.

 To Wash or Not To Wash – That Is The Question

In the US all eggs sold by major commercial egg operations have to be washed in a very specific way to get rid of any potentially nasty bugs on the eggshell.  The water has to contain detergent and be heated to at least 90 degrees.  Then the washed eggs must be sprayed with a sanitizer and dried.  Clean eggs, so no problem, right?  Well, not completely.  The UK forbids the washing of eggs.  Remember the cuticle – that layer of “varnish” that keeps stuff from penetrating the porous eggshell?  When the egg is washed, the cuticle gets washed right off.  Once it’s gone anything the egg comes in contact with can soak right through the eggshell.  If salmonella or other bacteria soak through the shell, they find themselves in a wonderful, nutrient-rich environment and are so happy that they are soon at work churning out a bazillion little baby bacteria.

 To Fridge or Not To Fridge – That is The Other Question
Because washed eggs are vulnerable to bacteria soaking through the shell, another rule in the US is that eggs, after washing, must be refrigerated.  So, when you shop for eggs in the US, you head for one of those big refrigerated cases in the produce department.  In the UK, the eggs sit right on a regular old shelf at the ambient temperature of the grocery store.  “Well, sure,” you may be thinking, “The eggs have their cuticle, so they don’t need refrigeration.  But wouldn’t they be doubly safe if they were refrigerated as well?”  They don’t think of it that way in the UK.  Imagine you’re at the grocery store on a hot, humid summer day and you pick up a dozen eggs.  You pay the cashier, bag your groceries and head outside.  As soon as those cold eggs hit the humid summer air, condensation begins to form on the eggshell.  The eggs may actually become quite wet.  All that water provides a nice place for any bacteria on the eggshell to swim around.  If the eggs have been washed, it will all soak right into the egg.  In the UK the thinking is, “No cold eggs, no condensation.  Brilliant, mate!”

 Roll Up Your Sleeve and Stick Out Your Wing
So, our British friends go to the grocery store and buy their unrefrigerated cuticle encased eggs and perhaps feel safe from the ravages of salmonellosis.  But there’s still a way for bacteria to sneak aboard eggs.  Remember when I said salmonella could be inside the hen so the egg would be formed around the bacteria?  In that case, no cuticle, brick wall, or Star Trek force field on the outside of the egg will provide protection—the bacteria’s already inside!  And for that matter, no amount of American washing the outside of the egg will remove the bacteria from the inside, either. 

Red Lion Stamped Egg (Borb)

 With the internal bacteria situation, the Brits found themselves to be on a very sticky wicket indeed (a phrase I’m pretty sure I picked up from a rerun of some old BBC sitcom).  But they found a solution—salmonella shots for chickens.  By inducing salmonella immunity with vaccine, they reduced the likelihood of salmonella even being present in the intestines of egg-laying flocks.  No salmonella in the chicken poop means no salmonella contaminating the eggs on the inside or the outside, and no salmonellosis in the egg-eating public.  Salmonella vaccinations got underway in the late 1990’s.  The number of reported salmonella cases in the UK dropped from 14,771 in 1997 to just 581 in 2009.  Bear in mind that there is no law in the UK mandating that egg producers vaccinate their hens. Instead there’s the red lion program—eggs coming from salmonella-vaccinated hens get to have a red lion stamp—not on the egg carton, but right on each and every egg.  And if you are buying eggs, why wouldn’t you buy the red-lion-stamped safe eggs?  90% of all eggs sold in the UK today have the red lion stamp—consumer pressure works!  In the US, there is no federal regulation or program stipulating salmonella vaccinations.  Egg producers have lobbied against it due to the increased costs vaccinations would engender.

Vaccinated American Hens
And that’s the situation my reader, Rick, walked into when he visited the US from the UK.  His question to me was about the status of salmonella vaccination in the US, and with the first part of this post under your belt, I think his question and my response will make perfect sense to you.  Bottom line, “Buy CA SEFS Compliant eggs!”  Here are the emails:

 Hi Randy,
I have been trying to find out the prevalence of chicken vaccination for salmonella. Having lived in the UK for a number of years, as you know, the standard there is to vaccinate egg-laying hens, but not to wash/refrigerate. We've been trying to determine how common vaccination is here. I saw somewhere (maybe your website) that California's standards require vaccination for eggs sold there. Has this pushed vaccination rates up? Or if you live in, say, Florida, are you likely to still have eggs from non-vaccinated hens?
Best,
Rick

 Hi Rick -
Great question. The fact that you're even asking it shows me that you have a better underlying knowledge of the eggs you buy and eat than the typical consumer.
 With the implementation of 3 CCR 1350 back in 2013, California mandated that all eggs sold in California meet a number of criteria.  One was that the hens producing those eggs be vaccinated for Salmonella enteritidis. This didn't just affect egg producers in California.  Egg producers, regardless of where they were located, had to abide by these regulations if they wanted to sell eggs in California.  That left egg producers three options:  First, they could decide to not follow the regulations (not vaccinate) and stop selling eggs in California - bear in mind that California is a huge market.  Second, they could maintain two flocks - one that followed the regs for California sales and a second one that didn't - for sale everywhere else.  This solution presents some large logistical problems and would no doubt be expensive.  Finally, they could follow the regs and vaccinate their entire flock and just sell California compliant eggs everywhere.  

 So, what did egg producers do? Interestingly, all three options are being used.  So, if you're shopping for eggs at your local grocery store and you would like eggs from producers that follow the California guidelines, and from hens that have been vaccinated, you need to look for the  “CA SEFS Compliant” (California Shell Egg Food Safety Compliant)  label on the carton.  My guess is that eggs from cartons that don't display that label probably come from hens that have not been vaccinated.
 As always, even though eggs from vaccinated hens provide an additional layer of assurance about the safety of those eggs, you still need to thoroughly cook them, as you would any animal product.
Regards,
Randy