Notes from the field: Yersinia enterocolitica infections associated with pasteurized milk --- southwestern Pennsylvania, March-August, 2011.

On July 22, 2011, a pediatric infectious disease physician reported a culture-confirmed case of Yersinia enterocolitica infection to the Allegheny County Health Department (ACHD), Pennsylvania. Two additional cases in Allegheny County with onset around the same time were identified by Pennsylvania's version of the National Electronic Disease Surveillance System aberration detection algorithm, which routinely evaluates disease reports, searching for unusual events. During March-August for the 3-year period 2008-2010, three cases of Y. enterocolitica infection had been reported in Allegheny County and a total of five in southwestern Pennsylvania. Subsequent review of the surveillance data identified 16 culture-confirmed patients with symptom onset during March 24-August 5, 2011. Patients were aged 1-75 years (median: 26.5 years). Seven patients (44%) were hospitalized; three were admitted to an intensive care unit.