Recently the Journal of Food Protection published a study that shows the risk of contamination of the Listeria bacteria and subsequent growth during storage.
"Mitigation strategies during dicing and proper refrigeration are essential to minimizing potential health risks associated with diced celery."
The disease Listeriosis (caused from the aforementioned bacterium) causes gastrointestinal illness. In some cases you can get a blood or brain infection. Infections in early pregnancy can cause miscarriage; in late pregnancy stillbirth or death of the newborn. Listeria infection has different manifestations depending on the organ it infects. In short, don't mess around with Listeria.
The takeaway here is, first of all, don't eat celery. Second, if you feel compelled to dance with the devil, at least, for God's sake, dice your own.