Quebec's health department has confirmed to CTV News that one person in the province has died of an E. coli infection that may have been caused by eating contaminated walnuts.

The Ministère de la Santé et des Services sociaux (MSSS) wouldn't release details on the patient's death, except to note that the person had underlying health problems before the E. coil illness.

There have been at least 13 cases of E. coli infection in Quebec, Ontario and New Brunswick. Nine of those cases are concentrated in Quebec.

Health Canada is concerned the cases may be connected to a recall of walnuts distributed by Quebec-based Amira Enterprises. But there has been no direct link between E. coli and the walnuts, and tests by the company have not shown any trace of the bacteria.

Food-borne illness outbreaks are notoriously difficult to investigate. Symptoms can develop anywhere from one to 10 days after eating contaminated food, so those who become ill often have trouble remembering precisely what they ate ahead of the illness.

Earlier this week, the Public Health Agency of Canada, along with Health Canada and the Canadian Food Inspection Agency, issued an advisory warning Canadians against eating raw, shelled walnuts bought from bulk bins or from certain packages.

The advisory said some of the patients have experienced serious illness: 10 have been hospitalized and three developed a serious condition called haemolytic uremic syndrome (HUS). The patient who died would have been among the three who developed HUS.

HUS is a potentially life-threatening illness typically caused by E. coli that causes bloody diarrhea from the abnormal destruction of red blood cells. The red blood cells can clog the filtering system in the kidneys, which can eventually shut down.

The CFIA says the affected nuts were sold in Quebec, Ontario and Atlantic Canada since Jan. 1. They may be contaminated with E. coli O157:H7 -- the same strain of the E. coli bacteria that killed seven and made hundreds of others sick 11 years ago in Walkerton, Ont.

Amira says it learned of the E. coli outbreak on Apr. 1 and began a national, voluntary recall on Sunday, Apr. 3. It says that tests conducted at its facilities have so far come back negative for any trace of E. coli.

The nuts were sold from bulk bins as nut halves, walnut pieces and walnut crumbs. They were also distributed in packages by Amira Enterprises under three product names: Amira, Tia and Merit Selection. All package sizes, all lot codes and all best before dates are affected by the recall.

PHAC, Health Canada and the CFIA say they are continuing to actively investigate the outbreak.

PHAC reminds Canadians that food contaminated with E. coli may not look or smell spoiled.

Anyone with raw, shelled walnuts in their home can reduce the risk of E. coli infection by roasting the walnuts prior to eating them. Place the nuts on a cooking sheet and bake at 350 degrees Fahrenheit for 10 minutes, turning the nuts over once after five minutes.

Symptoms of E. coli infection include severe abdominal pain and bloody diarrhea. Although most people recover within seven to 10 days, pregnant women, people with compromised immune systems, young children, and the elderly are most at risk for developing serious complications.