TORONTO - 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.
"The one thing that stood out -- and we were sort of suspecting this and looking for it from our previous investigations ... the romaine lettuce was the only thing that was significantly related to the ill cases," said Doug Sider, the Niagara Region's associate medical officer of health.
There are 128 confirmed or probable cases of E. coli 0157: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.
If a link to romaine lettuce is confirmed, investigators would identify restaurants' suppliers, then go to their distributors and importers and try to trace the supply back to the farm level, Cardinal said.
Two restaurants, M.T. Bellies in Welland and The Little Red Rooster in Niagara-on-the-Lake, were linked to the Niagara region's outbreak. Both restaurants closed to assist authorities with their investigations, but reopened last week.
Most of the 14 confirmed cases in Niagara Region were linked to one of the restaurants, but those that weren't seem to point to the lettuce as well, Sider said.
"A small number weren't linked to the restaurants although they ate common produce that we were concerned about, which has largely been a focus on romaine lettuce," he said.
Sider said the handful of people not linked to either M.T. Bellies or The Little Red Rooster ate elsewhere, but still ate romaine lettuce.
While analysis suggests produce is the source of contamination, the two restaurants do not share a supplier, so the CFIA will see if there was a common point of distribution, Sider said.
As for the outbreak itself, it appears to have subsided, he said.
"There's no evidence that there's an ongoing produce contamination problem, certainly here in Niagara Region," he said.
"Whatever occurred seemed to have occurred back in the middle part of October."
Most of the other regions are focusing on the same time period, from about mid- to late October. There are 14 confirmed cases in Niagara, five each in Halton and Guelph and two in Waterloo.
Monir Taha, the associate medical officer of health for the Halton Region, said their investigation had narrowed the suspect food groups to lettuce and raw vegetables.
"Our results are consistent with the romaine lettuce theory," he said, adding that co-operation between the health units and the provincial ministry has helped.
"If ours had been the only outbreak we might not have been able to point back to romaine lettuce ourselves."
There are a number of ways people could have become sick without eating romaine lettuce, if it is indeed the source of contamination, Taha said. For example, people could have eaten raw vegetables prepared on the same cutting board.
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.
A Harvey's restaurant linked to the outbreak that was closed Oct. 12 will reopen Wednesday after being cleared by health officials.
A thorough sanitization was done, and public health officials will increase their surveillance of the restaurant once it reopens.
There are 251 people with confirmed, probable or suspected cases of E. coli in the North Bay outbreak, and of those, 50 have been confirmed.
The child reportedly remains in Toronto's Hospital for Sick Children with a complication of E. coli -- hemolytic uremic syndrome, which can cause acute and chronic kidney failure, particularly in young children.
