— -- A petting zoo and animal barns at a Maine county fair are being investigated after two children who visited the fair were infected with E. coli, health officials said.
The Maine branch of the Centers of Disease Control and Prevention has launched a probe into the cases and is currently focusing on the children's visits to the petting zoo and animal barns at the Oxford County Fair, officials said.
"Maine CDC is working with the State Veterinarian and the Department of Agriculture, Conservation and Forestry to investigate the fact that each child attended the Oxford Fair and visited the animal barns and petting zoo," a CDC spokesman said in a statement.
"Shiga toxins," which are associated with E. coli, were found in laboratory tests earlier this week, health officials said.
The Oxford County Fair did not immediately respond to calls from ABC News seeking comment. The fair ran from Sept. 16 to 19.
One of those infected was identified by his family as 20-month-old Colton Guay, according to ABC's Portland affiliate WMTW-TV. A week after visiting the fair, the toddler developed symptoms of E. coli infection, including severe diarrhea, before he was hospitalized, his father told WMTW-TV, noting that Colton later died from a complication called hemolytic uremic syndrome (HUS).
"To the best of our knowledge, he never touched an animal but he was in the petting zoo," Colton's grandmother, Lucy Guay, told ABC News today, adding that Colton was admitted to the hospital on Sept. 29 and died on Monday.
The boy's parents are devastated, she said. "He had a smile that would win everyone over. He was daddy's little buddy and mama's little man," she said.
The CDC has not disclosed the condition of the other infected child.
HUS is most likely to affect young children with E. coli and occurs when red blood cells are destroyed and start to clog the kidneys. Younger children can be especially susceptible to E. coli infections, since their immune systems are not fully developed.
E. coli bacteria is naturally occurring and often live in the intestines of both people and animals. If people are exposed to a strain of E. coli bacteria that is infectious, they can become ill. The bacteria is often spread through contaminated food or water or contact with animals or infected people.
"As the agricultural fair season winds down, it's important that those who are exposed to animals and their environment wash their hands thoroughly with soap and water," a CDC spokesman said in a statement. "This offers the best protection against E. coli."
State veterinarian Dr. Michele Walsh told WMTW-TV that her office was working with Oxford County Fair officials and that inspectors are looking to sample animals for signs of the bacteria.
"It's a challenge to get a smoking gun," Walsh told WMTW-TV about testing animals.