But, if you were my patient, in the absence of symptoms, I would not run a
test for
Listeria, nor would I recommend that you have it done elsewhere.
The CDC reports about 1700 cases of Listeriosis in the
US each year. This seems like a lot until you remember that the population of the US is
1.2 billion people. So the risk is 1700/1,200,000,000 which is so small that my calculator won't give the answer without a power of 10.
I hope this will reasure you somewhat.