HALIFAX -- Health officials in Nova Scotia were narrowing down possible culprits in an E. coli outbreak Monday as three more cases of the bacterial infection were confirmed in the province.

The latest cases of E. coli 0157 brought the total number of confirmed cases to 10 since the Health Department first reported the outbreak Friday.

Nova Scotia's chief medical officer of health, Robert Strang, said two of the newest cases were in the Capital District Health Authority, while the other was located in Cumberland County. The illness was also confirmed last week in the Truro, New Glasgow and Antigonish areas.

The strain of E. coli is the same one found during the Walkerton, Ont., water disaster in 2000 that killed seven people, but Strang said people should not be alarmed.

"Whatever it is, it's not widely, widely spread," he said in Halifax. "Otherwise we would be seeing more people ill."

The province's Health Department said all patients have been seen by health care professionals and are either recovering or recovered, though two people remained in hospital Monday.

Strang said those affected by the outbreak ranged in age from 18 to 83.

He said his office was getting closer to pinpointing the source of the outbreak and trying to determine if there is a link with five cases of E. coli 0157 confirmed last week in New Brunswick.

Strang said after interviewing those affected by the illness, it's believed the outbreak stemmed from a type of processed produce -- lettuce that's been chopped and packaged, for example.

"Right now we're looking at exposure more through restaurants ... than food that's been distributed through groceries," Strang said.

He said officials have narrowed the investigation down to about a dozen possible sources, and specimens have been sent to a national lab in Winnipeg for further analysis.

However, Strang said the complexity of the modern food distribution chain -- which includes restaurants, wholesalers and suppliers --can hamper these kinds of investigations.

"We have made some progress and we're hoping over the next few days that we'll have something concrete, but acknowledging also that many types of outbreaks like this, at the end of the day, you're sometimes not able to come up with a conclusive answer."

The Health Department said last week the onset of the outbreak occurred between Dec. 23 and 26, but Strang said two of the most recent cases fell ill after that period.

He said it's possible those people were exposed days before they began showing symptoms because of the bacteria's 10-day incubation period.

The symptoms of E. coli can include diarrhea, fever, cramping and general unwellness.