date:Aug 25, 2012
The outbreak investigation began July 9, when the first case of E. coli infection was confirmed, though the picnic took place on July 3. That six-day gap made it especially difficult for investigators to trace back to the root cause of the outbreak, said Bill Wharton, spokesman for Dayton Montgomery County Public Health.
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.