Public health officials and health care providers are trying to determine where a Seattle-area family picked up E. coli, but have not yet come up with any answers.

First, 16-month-old Adelido started to show symptoms of E. coli two weekends ago, according to KING 5 News. Then, 3-year-old Carlitos became ill a few days later. Right after both boys got out of the hospital, their grandmother who often babysits them checked into the hospital with the same symptoms.