Persons who attended a wedding on August 24, 2013 at Spring Lake Park in North Mankato became ill with E. coli O157:H7. Approximately 30-50 people attended the wedding. Twenty-one attendees were interviewed. Eleven persons residing in 8 households met the case definition. Onset dates for cases ranged from August 24 to August 29. Eight persons were laboratory confirmed with E. coli O157:H7 with MN PFGE pattern EXHX01.0047/EXHA26.0332. The additional 3 cases sought medical care and submitted specimens for testing but tests were negative. Five cases were hospitalized. One developed Hemolytic Uremic Syndrome. There were no deaths.

Food and drink items served at the wedding were prepared by family members. A family member of the couple provided meats from a family-owned meat locker in Iowa. Multiple guests reported that coolers used to transport raw meat may not have been properly cleaned and were subsequently used to transport ice that was used in the drink coolers for temperature control. In a univariate analysis, consuming mini-cupcakes and nuts/mints were significantly associated with illness.

On September 12, 2013 the Centers for Disease Control and Prevention posted a national cluster alert (1309MLEXH-5) that eventually included the eight laboratory-confirmed Minnesota wedding associated cases and 3 additional cases in Minnesota who did not attend the wedding. Isolates from wedding guests were indistinguishable by MLVA and distinct from the non-wedding guests in Minnesota. No specific commonalities were identified in the national investigation.

Minnesota investigators concluded this was an outbreak of E. coli O157:H7 infections among guests at a wedding reception. Contamination of food or drinks from raw meat or from an infected attendee may have contributed to the outbreak. The outbreak was hindered by lack of information from the wedding hosts, and therefore the precise source and mechanism of contamination could not be confirmed.