On May 25, 2007 the Fresno County Department of Community Health (FCDCH) was notified of a possible outbreak of E. coli O157:H7 infections linked to a private event in Fresno County a few days before.  The next day, FCDCH began receiving reports from local hospitals of patients testing positive for E. coli O157:H7, and so opened an investigation.  See FCDCH Final Report.  When additional cases were reported throughout the weekend, the FCDCH Emergency Response Team contacted on-call communicable disease staff to come help.

FCDCH collected food histories from each of the identified ill persons. Initially, it looked as all but two of the cases had consumed tri-tips cooked by a single restaurant—the Meat Market in Fresno.  The tri-tips had been eaten at several events during the previous week where multiple persons had become ill.  After further investigation into the two seemingly unconnected cases, it was discovered that they had eaten the cooked tri-tips from the Meat Market at a school carnival event on May 18, 2007.   FCDCH thus concluded that the probable source of infection was the tri tips prepared by Meat Market.  This conclusion was further confirmed when food samples that had been collected from one of the events—a graduation party—tested positive for a strain of E. coli O157:H7 that turned out to be genetically indistinguishable from that which had infected all of the outbreak victims.

As part of the investigation, an inspection of the Meat Market restaurant was completed on May 29, 2007.  According to the FCDCH report:

Violations were observed [including]:  a lack of hot water at the handwash sink (hot water valve was turned off), empty soap dispenser at the handwash sink, expired food safety certification, incorrect set-up at the three-compartment sink for manual sanitization, two-door refrigeration unit storing potentially hazardous foods at the incorrect temperature (55 degrees) and incorrect storage of food products (raw meat stored above raw vegetables and cooked product in the walk-in refrigerator).

See Final Report.

Ultimately, FCDCH concluded that the tri-tips prepared at the Meat Market had been the cause of the E. coli O157:H7 outbreak.   According to the FCDCH Final Report, there were 29 confirmed cases and 94 suspected cases linked to the outbreak.

Here is a great video from the CBC on the risks: