State health officials continued to investigate the cause of two cases of E. coli infections on Thursday, after one toddler died and another was still undergoing treatment at Maine Medical Center.

Seventeen-month-old Myles Herschaft of Auburn was in critical condition Wednesday from hemolytic uremic syndrome – a disease caused by the E. coli bacteria – but was upgraded to fair condition by early evening Wednesday. On Thursday, Myles was still in fair condition, hospital officials confirmed.

Colton James-Brian Guay of Poland, 20 months, died Monday from hemolytic uremic syndrome, a type of kidney failure, the toddler’s family reported.

Both children had visited the petting zoo at the Oxford Fair in September, but state officials have not confirmed whether the toddlers contracted E. coli from the petting zoo.

John Martins, spokesman for the Maine Center for Disease Control and Prevention, said the state does not expect “complete test results” from manure and bedding at the Oxford fairgrounds until next week.

“We are awaiting test results of environmental specimens collected yesterday, as well as the test that determines what strain of E. coli was present in these two cases,” Martins said in a statement. “Debris from the poultry area, from outside the pens and livestock area (petting zoo) are being tested. We are continuing our effort to collect information that may point to other common links in these cases. At this point, we cannot rule anything out.”

Myles’ family reported on Thursday that he was improving and able to eat.

“Myles had some jello and applesauce. Later in the evening he cracked a smile, A blessing was present,” according to a post Thursday afternoon on the family’s GoFundMe web site. The family had raised about $3,000 by Thursday to help defray the cost of medical expenses.

“The family can’t thank everyone enough for the strong support. Team Myles continues to stay positive and support him in his fight,” the post said.

While it’s still unclear whether the petting zoo at the fair was the root cause of the E. coli, the state conducts random inspections of the fairs every year, making sure conditions are sanitary and that proper signage is posted. The fairs are required to post signs reminding people to wash up, and provide hand sanitizer stations.

E. coli is spread through undercooked food – especially ground meat – raw milk, or contact with contaminated fecal matter.

Maine had reported 26 cases of E. coli through Oct. 3, and 33 in 2014 to federal officials. The number of cases in 2014 places Maine at slightly above the national average per capita for E. coli contaminations, according to the U.S. Centers for Disease Control.

Dr. Dora Anne Mills, a former Maine CDC director and a vice president at the University of New England, said it’s possible but rare for petting zoos to be the cause of an outbreak.

“Most of the cases I saw during my 15 years there were from people drinking raw milk or eating undercooked meat,” Mills said. She said hamburgers should be cooked until well done, not just medium, to 160 degrees Fahrenheit, to ensure the bacteria is eradicated.

She said young children could contract E. coli if they visit a petting zoo, don’t wash their hands and then eat food.

“The fairs are particularly dangerous because people are eating finger food. Nobody goes around eating fried dough or french fries with a fork and knife,” Mills said.

Petting zoos have been identified as the causes of E. coli outbreaks in the past. In Minnesota, health officials in 2014 identified 13 people who had contracted E. coli from a traveling petting zoo. In 2004, over 100 people at the North Carolina State Fair became ill with E. coli infections, according to Bill Marler, an attorney who writes a popular food safety blog.

One of the most notorious E. coli outbreaks occurred in 1993, stemming from contaminated hamburger meat at Jack in the Box fast food restaurants. Several hundred people were sickened and four children died during the 1993 outbreak, according to news reports from the time.