The culprit was originally thought to be the raw chicken but after much investigation it was found to be the free range eggs used in the chocolate mousse which had been purchased at the farmers market held at the venue of the cooking classes earlier that day, and more specifically they found the bacteria was actually present on the shells not the interior of the eggs. When dealing with the government department responsible for the investigation they said that while this was a known issue world wide and is of particular concern with free range eggs and had resulted in a virtual holt to the free range egg industry in the UK, it is not well understood by the general public.
It is not good to wash the dirt off eggs as this can contaminate the eggs.
Chelsea, I try and collect the eggs every day, if the nest is dirty I pull out the rice hulls ( this is what we have on the floor and in the nest boxes), and put in clean rice hulls. If any of the eggs are dirty, I do wash them in warm water with a couple of drops of detergent, (not too much as it might perfume the eggs.). I just dip them into the water and then dry them with a cloth. I refrigerate them immediately. I have never had a problem. The mayo recipe is the only one i use that has raw eggs in it. All the eggs we use are cooked, either in cakes or boiled . I have given a lot of eggs away , over the years and no one has had a problem. I think that the problem with washing the eggs is if you use hot water. But I am not sure on this point.