BRISTOL, Tenn. (WJHL) — Less than three weeks ago, some Tennessee elementary school students took a field trip. Now, one family is facing multiple E. coli infections.

Grayson Hefflin, a kindergartner at Avoca Elementary, was among those who visited the Appalachian Fairgrounds in Gray, Tennessee, on September 26.

He is now one of at least seven children hospitalized as part of an outbreak of E. coli infections.

E. coli is bacteria, the CDC explains. Many strains are harmless, but there are some that can make you sick. Among those is Shiga toxin-producing E. coli, the strain health officials have determined the children were exposed to during their field trip.

Though health officials have not identified an exact source for the infection, they did provide resources on staying healthy around animal exhibits – a common place for germs like E. coli, cryptosporidium, and salmonella, according to the CDC.

Symptoms of an E. coli infection can vary from person to person but frequently include severe stomach cramps, diarrhea (which can be bloody), vomiting and fever. Infections can set in anywhere from one to 10 days after exposure, and most people are able to recover at home.

However, young children are at a higher risk of experiencing illness and more serious complications if infected by E. coli, according to Mayo Clinic.

Grayson’s mother is experiencing that now.

“Since September 26, it has been a myriad of different symptoms in our family,” Grayson’s mother Diedre Hefflin told Nexstar’s WJHL.

Hefflin said Grayson had minor symptoms on Sept. 27 but recovered fairly quickly.

About a week later, her 15-month-old, River, started acting fussier than usual. That didn’t raise any red flags, Hefflin said, as River is still teething.

“Saturday night is when it hit me that it was more,” said Hefflin. “At that point, we found out about the E. coli outbreak.”

River tested positive for Shiga toxin-producing E. coli (STEC) at Bristol Regional Medical Center on Oct. 7, Hefflin said.

As he was transferred to Niswonger Children’s Hospital, River continued to get sicker.

“Wednesday, he started vomiting, could not keep water down,” Hefflin said. “He had stopped eating, stopped drinking, totally.”

River began showing symptoms of hemolytic uremic syndrome, a complication associated with STEC that affects kidney and blood clotting functions.

On Oct. 12, River was transferred again, this time to East Tennessee Children’s Hospital in Knoxville.

Hefflin spoke with WJHL while River was in an operating room receiving dialysis ports and a peripherally inserted central catheter (PICC) line.

“Aside from all of the overload of just medical jargon and information, is just an overwhelming amount of emotions,” Hefflin said of the experience. “But God has brought us really through this, through His grace and through the prayers of so, so many people that have seen our story that are reaching out.”

Hefflin’s second youngest son Elijah is also showing E. coli symptoms but has not been admitted to the hospital.

Hefflin’s family isn’t the only affected; in fact, she said a few doors down from River at the PICU in Knoxville is another patient who attended the field trip.

“We’ve all banded together and become a little community supporting each other through all of the symptoms and the questions and the resources of knowing what to do and where to go,” said Hefflin. “I’m really thankful for that.”

Hefflin said River’s recovery will likely keep him in Knoxville for at least a month.