The calls started at 11 a.m. on Wednesday, June 10, three or four days after the parties, Sean McDermott, a spokesman for the Cook County Public Health Department, told the Chicago Sun-Times last year.
The first three complaints we had were hosts of parties, said McDermott. The common link at that time is that they had parties that were catered by Iwans Deli.
Iwans is famous for its potato salad... so famous that it had prepared a 2,300-pound batch for roughly 530 graduation celebrations and other events on June 6 and 7. Of the 20,000 people who ate the salad, an estimated 6,500 reported symptoms ranging from diarrhea to vomiting, chills, and headaches.
The culprit: E. coli O6:H16, also known as ETEC. Its the same bacterium that causes travelers diarrhea. Fortunately, its not as virulent as its cousin, E. coli O157:H7.
Health officials never figured out how it got into the potato salad, says Douglas Powell of the University of Guelph in Canada. These things are very difficult to trace back.
E. coli isnt the only bug that can make its way into prepared salads and other foods. In 1997, one person died and at least 43 others contracted hepatitis A from eating cole slaw sold at The Stage and Co. Deli outside of Detroit. The virus usually gets into food from infected food handlers.