Persons attending a party on May 5, 2014 were diagnosed with E. coli O157:H7. Multiple families attended the party. No other common exposures were identified among primary cases during the exposure period. Four children who attended the party were laboratory confirmed with E. coli O157:H7. One child who did not attend the party but had contact with a confirmed case was also laboratory confirmed with E. coli O157:H7. Four other persons were classified as "probable" secondary cases. Three children were hospitalized and two developed hemolytic uremic syndrome.

Reported activities at the party included playing with baby chicks, bottle feeding a calf that was being kept in a pen in the yard during the house party and playing in a small "kiddie" pool. Not all ill children had direct contact with the calf but parents reported there was cow manure in the yard where the children were playing.