Investigators had to rely on interviews with 117 attendees and an environmental assessment of the sites where foods -- including two roasted hogs -- were eaten and prepared.
More than 300 people attended the unlicensed event, with more than 100 contributing side dishes. Food was also provided by the event organizer, Neff's Lawn Care, which hosted it as a customer appreciation picnic and fireworks show.
Water samples at the picnic and hog roasting sites both tested negative for E. coli and other pathogens. By the time the investigation began, there was no food left over from the event to test, nor could public health verify the the cooking and holding temperatures of any of the 100-plus food items available.
Investigators interviewed 65 infected individuals and 52 unaffected to see if they could identify a particular meat item as the cause through a case-control study, but none of the items could be statistically pinpointed as suspect.
Of those ill, 14 were hospitalized and 3 developed hemolytic uremic syndrome, a kidney disease associated with severe E. coli infections.
