Nova Scotia's Department of Health and Wellness says three more cases of a potentially deadly strain of E. coli have been reported in the province, bringing the total to ten cases since Dec. 23.

"I think we want to be reassuring to the majority of Nova Scotians," said Dr. Robert Strang, the province's chief public health officer. "There's no need to be alarmed."

Five people have been hospitalized in Nova Scotia since the outbreak of E. coli O157 began. Three remain in a Halifax hospital while one person is in an Antigonish hospital.

Strang said the ten cases have affected people between the ages of 18 to 83. He said the incubation period of the strain is between one to 10 days, so health officials are not surprised the initial number of cases has grown.

Initially, seven people reported becoming sick between Dec. 23 and 26. On Monday, the province confirmed the three new cases.

One of those new cases fell in the initial date range, while the other two developed in the following week.

The province said all the patients are recovering or have recovered. The newly reported cases are from the Capital Health District and the Cumberland District Health Authority.

Source unknown

Strang said the likely source of the outbreak is produce. He said one of the possibilities being investigated is lettuce that may have been chopped or processed.

How to prevent spread of E. coli Wash, peel raw vegetables and fruit

Cook meat properly

Wash hands and surfaces after handling raw meat

Consume only pasturized dairy products

Strang said the patients may have been exposed in restaurants.

"From the outset of our hypothesis — and it's a fairly solid one — is that we're looking at a manufactured food product or a food that's been processed in some way that's been widely distributed," he told reporters.

Strang described his investigation as detective work — eliminating various possibilities as they interview patients.

Specimens will now be sent to a national lab for testing to see if the cases share the same sub-strain.

Strang said health officials are working closely with health officials in New Brunswick, where several cases of the same strain of E. coli have also been reported.

E. coli O157 is the same strain that killed seven people in Walkerton, Ont. in 2000.

Symptoms of E. coli resemble gastro-intestinal illness, such as severe cramps, bloody diarrhea, abdominal pain and vomiting.