In October 2011, the Minnesota Department of Health (MDH) Public Health Laboratory (PHL) identified an outbreak of non-O157 Shiga Toxin E. coli (STEC) and Cryptosporidium parvum among persons who had visited an apple orchard where animals were present.

Four cases of E. coli O111:NM (stx1 only) infection with the outbreak subtype were identified. All had visited the orchard on October 8, 2011. Three Cryptosporidium cases were identified through routine surveillance, with illness onset dates of October 15 or October 16. These cases had visited the orchard on October 8 or 9. An ill family member of a laboratory confirmed STEC case tested positive for the outbreak of strain of E. coli O111:NM and also for C. parvum with subtype BGP16a. The case had visited the orchard on October 9 and had illness onset on October 17.

Twenty-six orchard patrons representing 6 independent groups were interviewed. In addition to the 8 laboratory confirmed cases, six additional patrons were identified who met the case definition.

All 14 cases were combined for data analysis. By univariate analysis, drinking a sample of unpasteurized apple cider during a pressing demonstration was significantly associated with illness (14 of 14 cases vs. 5 of 9 controls; odds ratio, [OR], undefined; p=0.01). Having contact with petting zoo animals at the orchard was inversely associated with illness (8 of 14 cases vs. 9 of 9 controls; OR, 0;95% confidence interval, 0 to 0.8; p= 0.048).

Animals in the petting zoo at the orchard tested positive for the outbreak strain of Cryptosporidium, a strain of STEC closely related to the outbreak strain, and other potential human pathogens. The exact mechanism for contamination of the cider was not identified. However, the petting zoo animals were the ultimate source of the pathogens that caused the outbreak. The most plausible scenario is that workers who cared for the animals served as mechanical vectors for the pathogens from the animals to the cider pressing equipment.