Federal health officials are hunting down the cause of an "alarming'' outbreak of E. coli infections in Manitoba, and suspect hamburgers served at local restaurants may be the source of most of the cases.

The outbreak coincides with several reported E. coli cases in other provinces and has prompted the Canadian Food Inspection Agency to lead an investigation into the infections, many from the same strain of the bacteria.

Dr. Pierre Plourde, a medical officer with the Winnipeg Regional Health Authority, said 10 Winnipeggers and at least one person in rural Manitoba have come down with E. Coli infections since May 7.

Those stricken range in age from six to 79.

Plourde said nine of the cases may have been from hamburgers purchased at restaurants. The remaining person likely became ill from purposely eating raw hamburger meat.

Plourde said he didn't believe anyone in Manitoba had become seriously ill from the tainted meat. Most had symptoms that included bloody diarrhea, inflamed intestines and vomiting -- symptoms common to most E. coli cases.

It's not unusual for city and provincial health officials to get two or three reports of hamburger-related E. coli during peak barbecue months. But with reports five times the usual amount, combined with a common reoccurring strain, a red flag has been raised.

"The fact that several of the cases of infections are the same strain of E. coli is alarming,'' said Plourde.

"This signals a warning that the meat may have come from a common packing plant. And the (Canadian Food Inspection Agency) is hot on the trail, trying to find out if there is an identifiable supplier of this meat.''

E. coli is a bacteria commonly found in the intestines of animals and humans. It often shows up in ground beef contaminated during slaughter, when infected cow intestines taint the surface of meat.

E. coli is particularly dangerous when it is further mixed into the meat during the grinding process.

Eating undercooked meat tainted with E. coli can cause kidney failure and even death, particularly in children, seniors and those with compromised immune systems.

E. coli infection can be prevented in several ways, including cooking ground beef until it is completely browned.

Since July 5, the federal inspection agency has been investigating the source of E. coli cases in British Columbia, Alberta, Quebec, Manitoba and possibly Saskatchewan.

A spokesman in Ottawa said the investigation is being conducted with the help of an intestinal disease database that has been in use for the past month or two.

The Web-based surveillance system tracks intestinal bacterial infections such as E. coli.

Plourde said this is the database's first success in tracking a bacterial outbreak in several provinces.