SAN DIEGO _ Environmental and animal testing has failed to reveal a clear source of the deadly E. coli outbreak among San Diego County Fair visitors.
In an update published Wednesday afternoon, the county health department said that none of the 32 environmental samples, nor any petting zoo, pony ride or cattle testing, have come back positive for O157:H7-type E. coli bacteria. That was the kind detected in the 11 confirmed outbreak cases, including 2-year-old Jedidiah Cabezuela, who died of severe complications after visiting animal areas of the Del Mar Fairgrounds on June 15.
All 11 cases reported having animal contact during fair visits, and administration, acting on the advice of local public health officials, closed all such exhibits to the public on June 29.
Dr. Eric McDonald, medical director for the county's epidemiology and immunization services branch, said Wednesday evening that the common thread among all 11 cases means that the original hypothesis about the outbreak's origins remains unchanged.
"Even though we have not found a specific animal that we can say the outbreak came from, we know that the cases all were people who went to the fair and had animal exposures in the livestock barn area," McDonald said. "It is likely that an animal or an environmental exposure in the livestock barn is where they were exposed."
While all petting zoo and pony ride animals were tested, only two cattle from the livestock barn were similarly checked out. The majority of the animals present left the fairgrounds before samples were collected.
