In August 2011, two cases of E. coli O157:H7 infections were detected through routine surveillance by the Minnesota Department of Health (MDH) Public Health Laboratory (PHL). Both cases were one-year-old males and both cases attended the Freeborn County Fair held from August 2-7 at the county fairgrounds. Neither child required hospitalization.

Both cases had exposure to the petting zoo and the 4-H animal barns. One case remained in the stroller while in the petting zoo and had no direct contact with any animals there. He did have contact with a goat in the 4-H animal barn. The other case had direct contact with goats, sheep, kittens, and baby chicks while in the petting zoo and a sheep in the animal barn. Parents of both children reported washing hands after visiting the barns.

Buildings had been roughly cleaned at the time of the MDH staff visit on August 24. Approximately 20 environmental samples were taken from multiple locations in the 4-H barn and the petting zoo building. One sample was positive for E. coli O157:H7 but the isolate was >6 bands different from the outbreak strain by PFGE. Fecal samples were collected from four sheep displayed at the fair. Multiple STECs were detected but all isolates were >6 bands different from the outbreak strain.