European health officials who have been tracking down the source of one of the worst outbreaks of E. coli admitted that they may never actually find a smoking gun. They said that it is an unfortunate fact when it comes to food poisoning.

The bacteria have already affected 1,500 people in Europe and most of them said that they ate tomatoes, lettuce, or cucumbers. However, health officials who have been testing produce all over the continent have not yet found any vegetable with a strain of E. coli.

Atty. Bill Marler, a lawyer specializing in food poisoning, said that the signs of the infection appear days after the food that has caused it has been thrown out. He, therefore, said that the trail gets vague very quickly.

Professor Paul Hunter from England’s University of East Anglia said that there is a pretty huge chance that we will not find where the outbreak originated. In fact, he pointed out that in most foodborne incidents, there are no definitive answers as to what specific food caused it.

The national health agency of Germany announced on Wednesday that at least 1,530 people there had been inflicted by the dreaded E. coli germ. To date, 17 have already died and 470 are suffering from a kidney failure (a complication of E. coli infection that used to be considered rare).

According to the European Food Safety Authority, they have very limited data on the presence of E. coli strains in Europe. They also admitted that the current surveillance systems across Europe are not yet well coordinated.