A 2-year-old Cleveland County boy remained hospitalized Friday as state officials work to pinpoint the cause of an apparent outbreak of E. coli that has sickened the toddler and many others across North Carolina.

Hunter Tallent of Shelby underwent a third day of dialysis treatments in Charlotte on Friday. His is one of 26 E. coli-related cases the state is investigating. North Carolina health officials said all but three people had visited the state fair in Raleigh.

Hunter is the only victim reported from the Charlotte region, and one of five hospitalized on Friday, according to state health officials.

Hunter and his parents, Lindsay and James Tallent, went to the fair Oct. 15. A few days later, their youngest son fell ill with nausea and diarrhea. He wouldn’t move around much.

Tests have confirmed that 10 of the 26 suspected cases were caused by E. coli; the rest remain under investigation, Division of Public Health officials said in a statement. Public health officials say they consider the State Fair to be the probable cause for the outbreak and plan to talk with some attendees to try to determine the specific source.

A petting zoo was the source of a 2004 E. coli outbreak at the N.C. State Fair that sickened 108 people.

Lindsay Tallent says the family strolled through the barns to look at cows and other animals but says they did not touch any animals. Hunter ate a hot dog, corn dog, some pizza and ice cream, and drank lemonade, his mom said.

Doctors are not sure how long Hunter will remain in the hospital.