The extent of an E. coli outbreak linked to a Harvey's restaurant in North Bay, Ont., widened with a jump in suspected cases, health officials said Wednesday.

There are now 190 cases, including 36 lab confirmed cases of E. coli O157:H7, health officials in North Bay said.

The total of suspected and confirmed cases jumped from 158 reported on Tuesday.

"We believe the increase in the number of cases is largely due to people who are still reporting their symptoms and are within the expected timeframe of the outbreak," the North Bay Parry Sound District Health Unit said in a statement.

The cases are spread across nine health unit districts in Ontario and one in Quebec, and the majority remain linked to the Harvey's on Algonquin Avenue in North Bay, the city's health unit said.

All of the initial food samples collected on Oct. 12, when health officials shut down the restaurant, have tested negative for E. coli strain.

All of the packaged food from the restaurant have also tested negative for E. coli, according to the Canadian Food Inspection Agency.

The investigation has turned to food handlers, said CFIA spokesman Mark Richard.

It is too early to conclude that a person was the source of the contamination he said.

Stool samples from employees will be tested for the bacteria, Richard said.

Meanwhile, local investigators are looking for any differences between what those who were sickened ate and others who dined at the Harvey's and haven't fallen ill.

Health officials in North Bay opened a telephone call centre on Wednesday to gather more information from people who are not ill but ate at Harvey's between Oct. 1 and Oct. 12.

These people are asked to call (705) 474-1400 or 1-800-563-2808 until 7 p.m. Wednesday.

Symptoms of illness from E. coli O157:H7 include diarrhea, which may be bloody, stomach cramps, and/or vomiting and possibly a fever.