I wouldn't trust it to be a "virus" or Salmonella unless they do tests that prove it! This "virus" that is going around, my DD had it about 3 weeks ago but the Doc. never did tests for it.
She started feeling nausea again this Thursday and when I took her to see the Doc. he said it may have been the peanut butter the whole time (we had a 2111 jar in our cupboard)! But he still didn't do any tests to make sure. Unless they vomit and have direahhea for a prolonged amount of time they don't test for anything at all. It's just not cost effective to test for any stomach bug (virus or salmonella) unless you end up in the hospital from it.
My DD has had four stomach "flu/virus" episodes since October. Far more than most kids have in a year. She's a healthy active kid. I have a cousin that also feeds his kids Peater Pan and his kids have had multiple bouts of stomach problems since last fall too.
This may be supposition but, in my opinion, things just don't seem to add up in favor of it being a "virus".
Unfortunatly, to answer your question, They will not take your peanut butter for testing, or want to record (or hear about) your illness, unless your children end up in the hospital.
If they do, then CDC and health departments will be all over that jar of PB!
RPocai