Dr. Eilish Cleary says at least some of the five New Brunswickers affected ate at restaurants during the past two weeks. (CBC)

At least two of five cases of a potentially deadly strain of E. coli in New Brunswick are linked, the province's chief medical officer of health has confirmed.

Dr. Eilish Cleary says she received preliminary test results on Friday morning that show a case in Saint John and a case in Fredericton have a very similar pattern of E. coli O157 and are therefore considered linked.

"So that tells us, again it gives us more information, that there is something unusual going on," she said.

Officials are still trying to determine the source and whether there is any link to a recent outbreak in Nova Scotia, said Cleary.

"We do that in two ways — one, we interview the individuals and see where they have been over the last couple of weeks, whether they’ve had connections between each other, and we also look at their food histories, where they’ve eaten, have they eaten in restaurants, have they eaten particular types of foods."

E. coli can be transmitted by eating undercooked meat, food contaminated during preparation, or from another person infected with E. coli.

There have been two confirmed cases of E. coli O157 in the Saint John region and three in the Fredericton area.

All five patients were seen in hospital emergency rooms, but only one had to be admitted to hospital, said Cleary.

The affected people are between the ages of 18 and 39 and likely contracted the bacteria over the holidays, she said.

"We know that many of them, if not all of them, have visited a number of restaurants in the past two weeks and so we will be having inspectors visit those restaurants to make sure that their food preparation is up to scratch," Cleary said.

Nova Scotia had seven confirmed cases of E. coli O157 over the holidays — three in the Halifax region, two in Antigonish and one each in Truro and Stellarton.

Two people were hospitalized, including one suffering from kidney failure, officials have said.

Dr. Robert Strang, Nova Scotia's chief public health officer, said it's possible the source is a food item sold in both Maritime provinces.

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

This particular strain of E. coli secretes a powerful toxin that can destroy red blood cells, leading to severe illness, high blood pressure and kidney damage.

It also led to the biggest beef recall in Canadian history last fall. The Canadian Food Inspection Agency recalled more than 1,500 beef products that were packed at XL Foods, a meat processing plant in Brooks, Alta.

E. coli O157 also put two Fredericton teenagers in hospital in July, including Micaella Boer, 18.

"We knew it was something really bad, but we had no idea what E. coli was because we never really thought of it," recalled her mother, Victoria Boer.

Micaella spent several weeks in a Saint John hospital undergoing a series of blood transfusions.

She still suffers some of the after effects, her mother said.

"She's tired. She just started engineering at UNB so it's hard for her to keep up like she used to."

An outbreak of E. coli O157 in Miramichi in April hospitalized at least 13 people.

Symptoms of E. coli O157 resemble gastro-intestinal illness, such as severe cramps, bloody diarrhea, abdominal pain and vomiting.