SHELBY — North Carolina health officials say an E. coli outbreak is responsible for the illness of 15 people who attended the Cleveland County Fair.

State health officials said Friday the number of people from Cleveland, Gaston and Lincoln counties who reported becoming sick after visiting the fair in Shelby increased by two children.

Ten children and five adults have become sick. Seven are from Cleveland County, five from Gaston County, and three from Lincoln County.

Several victims were treated and released from hospitals. A 12-year-old Gaston County boy is hospitalized in Charlotte in intensive care.

The bacterium is found in the waste of animals such as cattle, sheep and goats. Those who touch contaminated material such as food or animals can transfer the bacteria to their mouths or to other people, said Laura Gerald, state health director with the North Carolina Department of Health and Human Services.

Cleveland County Fair director Calvin Hastings said his organization tried to prevent E. coli problems.

"We're required by state law to have five hand-washing stations, and we had nine," Hastings said. "We borrowed some from the Mountain State Fair. And we had signs posted all around the grounds, reminding people to wash their hands."

The Cleveland County Health Department worked with food vendors to prevent problems, Hastings said.

More than two dozen people were sickened with E. coli last year at the North Carolina State Fair in Raleigh.

Officials say they have made a number of changes for this year's state fair, which opened Thursday, to prevent a repeat occurrence. The changes are designed to limit contact between fair-goers and animals - and to increase the distance between livestock and food vendors.

Symptoms usually involve vomiting, diarrhea and stomach cramps, and most victims recover in about a week.

"This infection can lead to serious complications. So parents should not send sick children to day care or to school, to avoid passing it on to others," Gerald said.