A 5-year-old Wright County boy appears to be fending off a fierce E. coli attack that killed his younger sister.

Kade and Kallan Maresh both suffered acute kidney failure after contracting a toxin-producing bacteria on July 9.

According to a post Monday on the family's CaringBridge site, Kade is "on the mend" after an up-and-down week of pain, vomiting and lab reports that showed few, if any, positive signs. The boy had blood transfusions and was on kidney dialysis last week.

Now the good news:

"All of his labs are starting to trend in the right direction," wrote his mother, Tyffani Maresh. "His appetite is coming back. He ate more yesterday than he has in weeks."

His grandmother is keeping him stocked with homemade food, and his personality is "starting to shine," Tyffani Maresh wrote. "It's so great to see he is finally starting to feel better."

She ended with, "Missing our sweet baby girl every second of every day. Snuggle your babies today."

The Minnesota Department of Health is investigating the cause of the infection. E. coli can be found in petting zoos, contaminated meat or produce, or swimming pools or lakes contaminated with feces.

For the Maresh children, E. coli led to hemolytic uremic syndrome (HUS), a complication of the bacterial infection.

Previously on their CaringBridge site, Joseph and Tyffani Maresh said the toxin from the bacteria attacked their 3-year-old daughter's kidneys and her neurological system.

She would have been 4 years old next month.

Deaths resulting from HUS, which causes kidneys to stop working and destroys red blood cells, are very rare.

The family said on CaringBridge that the two children began suffering from nonstop bloody diarrhea and vomiting a week earlier. After several visits to the emergency room, the two were rushed by ambulance to University of Minnesota Masonic Children's Hospital.

By Monday afternoon, a GoFundMe page had raised almost $71,000 to help the family with medical expenses.

Twitter: @rochelleolson