According to Canadian press reports, Romaine lettuce is the “prime suspect” in an E. coli outbreak in southwestern Ontario that has sickened at least 26 people, the Canadian Food Inspection Agency said Tuesday. The federal agency and health officials in the Niagara and Halton regions say preliminary tests suggest romaine lettuce is the likely source. There are 128 confirmed or probable cases of E. coli O157:H7 in the Niagara, Halton, Guelph and Waterloo regions. Laboratory testing has determined that cases in the four health units have the same DNA fingerprint.

“Romaine lettuce is the prime suspect,” said Rene Cardinal, an official with the CFIA.

The source of an unrelated outbreak of E. coli in North Bay, which left one child in critical condition and sickened up to 250 other people, has not been determined.