The Public Health Agency of Canada may think Shiga-toxin producing E. coli is no biggie, but tell that to the Niles sisters of southern California, who were both hospitalized with hemolytic uremic syndrome (HUS).

ABC 30 reports that Mariska and Willow were active and healthy kids with no medical history. Their parents thought it was a terrible case of the flu. Originally their pediatrician thought it was norovirus. But after days of worsening symptoms, they were admitted to Valley Children’s Hospital with E. coli.

13-year-old Mariska Niles is finally starting to improve after 16 days in the hospital. She’s had more blood transfusions than she can count along with excruciating stomach pain and she was hallucinating.

The sisters were diagnosed with E. coli HUS or typical hemolytic uremic syndrome but the girls had unique cases.

Dr. Molly Dorfman said, “There’s was pretty atypical. Particularly the severity of Willow’s case was very very severe.”

This form of bacteria usually originates from contaminated food or water products. Pinpointing the exact source has been difficult. They haven’t traveled anywhere recently. The family hadn’t eaten out lately. It’s likely other family members also ate what the girls did but did not become violently ill. Even more puzzling, Mariska and Willow rarely eat the same things.

9-year-old Willow’s kidney’s still are not working. She has been debilitated by toxins from the infection, and at one point couldn’t wake up. Both sisters have had blood transfusion and dialysis.