In late April 2014, public health and agriculture officials at the federal, state, and local levels initiated an outbreak investigation after receiving reports of reports of persons who had lab-confirmed E. coli O157:H7 infections.[1] Ultimately, a total of twelve persons from four states were identified as having been infected with the outbreak strain, which was identified by the PulseNet Pattern Identification Number EXHX01.0096/EXHA26.015. The number of infected persons in each state were as follows: Massachusetts (1 case-patient), Michigan (5 case-patients), Missouri (1 case-patient), and Ohio (5 case-patients).  The dates of illness-onset ranged from April 22 to May 2, 2014. The age of persons infected ranged 16 years to 46 years, with the median being 25 years. Seven patients (58%) were known to have been hospitalized, although no one died. The outbreak investigation was assigned CDC Cluster ID 1405MLEXH-1.

In interviewing the case-patients, public health officials found that eleven of the twelve (92%) reported eating ground beef prepared as a hamburger at a restaurant before becoming ill.  Officials conducted multiple traceback investigations of the ground beef used at restaurants where case-patients had reported dining. These investigations identified ground beef produced by Wolverine Packing Company as the source of the ground beef and thus the outbreak.

On May 19, Wolverine Packing Company recalled approximately 1.8 million pounds of ground beef that was potentially contaminated with E. coli O157:H7.[2]  This was a Class I Recall, which means that FSIS deemed the risk to the public health “High.” The ground beef had been shipped to distributors for retail and restaurant-use nationwide. The recalled ground beef bore the establishment number “EST. 2574B” inside the USDA mark of inspection and had a production date code in the format “Packing Nos: MM DD14” between “03 31 14” and “04 18 14.”

[1]           See CDC Final Outbreak Report,

[2]           See FSIS New Release, “Michigan Firm Recalls Ground Beef Products Due to Possible E. coli O157:H7,” .