The multistate outbreak of Shiga toxin-producing Escherichia coli O157:H7 infections has led investigators to Santa Barbara County, CA-based Adam Bros. Farming Inc., one of the eight farms identified in traceback. FDA’s traceback work suggests that additional romaine shipped from other farms could also be implicated in the outbreak.

CDC analyzed water and sediment samples from Adam Bros. Farming Inc. and found the outbreak strain of E. coli O157:H7 in sediment within an agricultural water reservoir located on the farm. Whole genome sequencing results showed that the E. coli O157:H7 found in the agricultural water reservoir was closely related genetically to the E. coli O157:H7 isolated from ill people.

FDA is continuing to investigate to learn more about how the E. coli bacteria could have entered the agricultural water reservoir and ways romaine lettuce from the farm could have been contaminated. Romaine lettuce from Adam Bros. Farming, Inc. farm is no longer available for sale.

As of Dec. 13, 59 people infected with the outbreak strain of E. coli O157:H7 have been reported from 15 states and the District of Columbia.

Illnesses started on dates ranging from Oct. 5 to Nov. 16. Ill people range in age from 1 to 84 years, with a median age of 26. Sixty-five percent of ill people are female. Of 50 people with information available, 23 (46 percent) have been hospitalized, including two people who developed hemolytic uremic syndrome, a type of kidney failure. No deaths have been reported.

Illnesses that occurred after Nov. 21 might not yet be reported due to the time it takes between when a person becomes ill with E. coli infection and when the illness is reported. This takes an average of two to three weeks.