I ran across this article about a week ago. It was first published after that Salmonella outbreak last summer. It explains some fascinating facts about the disease resistance of eggs due to certain enzymes found in the albumin.
It seems eggs, when uncooked, are remarkably disease resistant. First off, as the hen lays the egg it is coated with what is known as "bloom". It is a clear substance on the surface of the egg which dries very quickly and it seals all the pores in the egg shell. This keeps what is on the surface of the shell from getting inside the shell. I try very hard to avoid having to wash my eggs. I do this by keeping the nest boxes full of fresh, clean pine shavings and collecting the eggs several times a day. Washing eggs removes the bloom which is the first line defense for keeping bacteria out. Unfortunately at this time of year I end up washing quite a few eggs. As hard as I have tried I just can't get those silly girls to wipe their feet before heading into their boxes to lay!
Chicken eggs take 21 days to hatch... they are kept at a fairly constant temp of 100 degrees by the mother hen. Think about it... an egg sitting out in a chicken coop for 21 days at 100 degrees... most of them hatch healthy, disease free, chicks... something obviously keeps the pathogens at bay. So, left to the natural order eggs are pretty safe and disease resistant...but the key is "natural". Most eggs bought in grocery stores come from huge corporate egg farms... there is nothing natural about them. We all know about the battery hens in cramped cages but even most of those healthy looking brown eggs that say "free range" or "cage free" are not far off. Here is a picture of a "cage free" operation:
And the only requirement for being "free range" is that there is a chicken door that leads to an outdoor space. Most often it is a fenced concrete pad. There are small organic producers that do it right but they aren't the ones you find at the grocery store.
Salmonella is carried by the bird. If it infects her reproductive organs it will be passed on inside the egg. The most frequent cause is associated with rats and their droppings. As you can see with conditions as they are, controlling disease harboring pests and controlling the spread of the disease among the hens is near impossible... so even with antibiotics and pastuerizing the eggs outbreaks are not uncommon... especially when corporate farms try to cut corners to widen their profit.
Below is a picture of how my chickens live as well as most other back yard chickens. There are some people who refuse to try fresh eggs because they are not pasteurized. You are much safer eating a fresh unpasteurized egg from a local, small producer then you are any store bought egg. These chickens live normal chickeny lives and they are well cared for because we care about the birds and keep our coops and yards clean and disease free. We do not need antibiotics or pasteurization. When people find out there is no money to be made in raising chickens and selling eggs they ask me why I do it. I do it for two reasons the joy it gives me and because I want control over my food. I want to know it is from healthy stock, processed safely and humanely. All the disease outbreaks, whether it is from eggs, ground beef or peanut butter, happen despite all the rules, regulations and government oversite. The problem is in how the food is grown, produced and processed in giant, corporate farms and processing plants. This is not the way it was. Small, family farms provided locally grown food for most of our nation's history. We do not need more rules and regulations, we do not need more government inspectors... we need to invest in more small, family owned, farms and do away with corporate farms... they are what is making our food unsafe.