The number of E. coli cases under investigation rose to 27 Tuesday, with 18 confirmed, and North Carolina health officials opened a command center in downtown Raleigh to coordinate information as they work to trace the source of the bacterial outbreak, the News Observer reports today.
The strongest lead so far is a petting zoo at the N.C. State Fair, but health officials were exploring other possibilities.
Of the 27 cases under investigation, 14 have links to the State Fair, one attended the Cleveland County fair, six have not completed questionnaires with that information, and six did not attend the October fair in Raleigh.
From the article:

“We’re not certain where it came from,” said Bill Furney, a spokesman for the state Division of Public Health. “We’re looking at all possibilities.”
Furney said the North Carolina cases still appear to be animal-to-human infections, hitting mostly children. So far, he said, no secondary, human-to-human infections have occurred. Some of the children attended school, however, and state health officials are working to make sure that the bacteria don’t spread from that contact.
Spread of the bug can be stopped with good hygiene — in particular, frequent hand-washing. Furney declined to disclose where the children had attended school.