Image: CDC
I am not too familiar with the norovirus, so I should do some additional research. Apparently, it (or something similar) has hit thousands of children in Germany. The cause has not been definitively determined, but some of these cases have been confirmed as norovirus from food poisoning.
...the number of children that have fallen ill with vomiting and diarrhea after eating food from school cafeterias and daycare centers has risen from about 4,500 to 8,400.
Source: USA Today
