In the spring of 2015, an outbreak of Shiga Toxin E. coli (STEC) occurred, involving ten children in Morgan Hill, California.

Nine children from two neighboring families (Families B and C) in Morgan Hill were diagnosed with E. coli O157. One child in Family C developed Hemolytic Uremic Syndrome (HUS). Illness onset dates for these case patients ranged from April 23, 2015 to May 2, 2015.

Shared exposures among the children in Families B and C included consumption of raw (unpasteurized) goat milk obtained from a neighbor (Family A) and strawberries from a roadside stand.

A tenth case was detected through molecular testing. This case was also Morgan Hill resident but was not associated with Family B or C. The case consumed strawberries purchased from the same roadside stand as other outbreak cases but did not share raw goat milk exposure. Investigators determined that this case was exposed to one of Family A's cows prior to illness onset, including walking in the cow pen on the premises of Family A and petting the cow.

Santa Clara County Department of Health collected samples of strawberries from the roadside stand and 9 fecal samples from cows, goats and llamas on property owned by Family A. E. coli O157 was not detected in the strawberries.

Of nine fecal samples, five (55%) tested positive for E. coli O157:H7
including four samples of goat feces, and one sample of cow feces. PFGE analysis indicated that these five samples had a matching pattern combination to the outbreak strain; PFGE pattern EXHX01.0124/EXHA26.0015. This was an uncommon PFGE pattern combination in the PulseNet database. This evidence indicated that the clinical cases most likely acquired this strain of bacteria directly from the
environment or from animals on the property of Family A

Investigators concluded that the most likely source of the outbreak was exposure to animals belonging to Family A. Contributing factors for illness included insufficient hand washing after exposure to Family A’s animals, including walking in the cow pen and petting the cow. Consumption of unpasteurized (raw) goat milk may have contributed to illness of some of the cases. Finally, person-to-person transmission within Family B and C households could not be excluded as a possible transmission route.

The outbreak was assigned CDC Cluster Code 1505CAEEXH-1.