A Gaston County boy has died from complications of the E. coli infection, and state officials say a widening outbreak centered on the Cleveland County Fair has now affected 20 people.

North Carolina health officials did not name the victim. But a relative posted on Facebook that 2-year-old Gage Lefevers died on Friday after being treated at a Charlotte hospital.

“We extend our deepest sympathies to the family,” Al Delia, secretary of the N.C. Department of Health and Human Services, said in a news release. “Losing a child is a devastating thing for a family to endure and our thoughts are with them at this difficult time.”

On Saturday, health officials said the number of sickened people with either confirmed or probable E. coli had grown to 20, including 14 children. One of the victims is from South Carolina. The others are from Cleveland, Gaston and Lincoln counties and, like Gage, had attended the Cleveland County Fair, which was Sept. 27-Oct. 7 in Shelby.

Gaston County Health Director Chris Dobbins said the victims include three people who are on dialysis. Four of the victims have developed hemolytic uremic syndrome, or HUS, a severe and potentially life-threatening complication.

State officials said it is possible that the number of people sickened in the outbreak could grow, as symptoms can take up to 10 days to develop.

Symptoms can include vomiting, diarrhea and stomach cramps. Most victims recover in five to seven days, but the illness can be life-threatening for others.

E. coli infections cause approximately 265,000 illnesses each year in the United States, and about 100 deaths.

The state is working with officials in Cleveland, Gaston and Lincoln counties to try to determine the exact source of the outbreak, state epidemiologist Dr. Megan Davies said. Officials are interviewing families of those who are sick, as well as people who did not fall ill, to try to spot trends in their behavior. But at this point, Davies said, nothing has stood out.

“The only common thread is that they went to the county fair,” Davies said.

Gage’s great-grandmother, Linda Lefevers, had been posting updates on Facebook about him, writing on Wednesday that he was at Levine Children’s Hospital and his kidneys were not working properly. The next day, she wrote that Gage continued to struggle, adding that he went from “one symptom to another and the latest one is always worse than the one before.”

He underwent surgery Friday to relieve pressure on his brain, she said.

On Saturday, after Gage’s death, she asked for continued prayers for the family.

“We would rather he be here with us but that undoubtedly wasn’t the plan,” Linda Lefevers wrote on Facebook. “We are so blessed to have had this precious soul in our lives for almost 3 years but that doesn’t take away the pain we feel right now.”

The E. coli 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 N.C. Department of Health and Human Services.

In 2011, at least two dozen people were sickened by E. coli that was likely transmitted in the Kelley Building at the North Carolina State Fair in Raleigh. The Kelley Building is one of the permanent structures on the state fairgrounds where sheep, goats and pigs were housed and competed in livestock shows during the fair. No other exhibits, foods or activities were linked to the E. coli infections.

The illness was likely related to animal contact, though a state study didn’t implicate a specific animal or breed, Davies said at the time.

As this year’s state fair opened on Thursday, state officials stressed the need for fair-goers to follow safety precautions. Officials have said people and livestock will be separated as much as possible. Food vendors at the state fair have been relocated and hand-washing stations have nighttime lighting and more signs.

Cleveland County Fair director Calvin Hastings said earlier last week that his organization tried to prevent E. coli problems, including working with food vendors.

“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.”

Saturday, Gerald encouraged people who think they have become sick to seek medical help.

“This is a tragic reminder of the seriousness of this kind of infection, especially in young children,” Gerald said. “We want to remind anyone who is experiencing symptoms of E. coli infection who visited the Cleveland County Fair to see their doctor or health care provider right away.”

Officials agreed Saturday to resend information to doctors reminding them of the symptoms to look out for in patients. Staff Writer Meghan Cooke, researcher Marion Paynter, NBC Charlotte and The Associated Press contributed.