The Public Health Agency of Canada says romaine lettuce has sickened 21 Canadians in three provinces this fall.
Ten were so sick they had to be hospitalized.
The bacteria is E. coli 1057:H7.
But while romaine lettuce has been identified, the Canadian Food Inspection Agency still does not know where it came from, according to a website posting by the health agency.
That also means there has been no recall issued.
So far nobody has died.