The case of a toddler in the Interlake area whose death was related to E. coli infection appears to be isolated and of unknown cause, officials in Manitoba say.

Brooks Oliver, a two-year-old boy from Arborg, died in mid-June after developing complications from an infection with E. coli O157:H7, the same strain that contaminated the water supply in Walkerton, Ont., in 2000, killing seven people and making more than 2,000 ill. 

Brooks's sister also became sick but later recovered. Tests showed a third person described as having "shared activities" with the children also tested positive for the toxin produced by E. coli but did not become sick, health officials said.

E. coli: Where does it come from?

E. coli, short for Escherichia coli, is a type of bacteria commonly found in the intestines of animals and humans. There are hundreds of strains, but E. coli O157:H7 has been identified as the most dangerous to people, producing a powerful toxin that can cause severe illness. E. coli O157:H7 can contaminate ground beef during the butchering process. If present in the intestines of the slaughtered animal, it can get into the meat as it is ground into hamburger. The bacteria are also found in unpasteurized milk and apple cider, ham, turkey, chicken, roast beef, sandwich meats, raw vegetables, cheese and contaminated water. A deadly E. coli outbreak in 2006 was traced to spinach grown in California. Bean and alfalfa sprouts have also been recalled due to E. coli contamination. Fruits and vegetables that grow close to the ground are susceptible to E. coli contamination if, for example, improperly composted cattle manure is used as a fertilizer.

After an intensive investigation, Dr. Tim Hilderman, medical officer of health for the Interlake region, said the cases appear to be isolated.

"The municipal drinking water system has been ruled out. Restaurants that were frequented in this particular situation have been ruled out. Food-handling establishments that handled the food that the child would have consumed have been ruled out," he said Tuesday.

"Unfortunately, to this point, we have not been able to find out a specific cause."

Brooks's mother, Lynette Oliver, said parents have to recognize the symptoms of E. coli infection and act quickly.

"With my son going in on [June] 17 and being such a healthy boy, and to have passed away on June 23, it's just — to me, it's just so scary," she told CBC News on Wednesday.

"People need to be aware of the symptoms and how serious E. coli can be … and I would just like more public awareness so people are more serious.  We need to get on, like, the research and get a vaccination or something to prevent our children from dying."

E. coli bacteria come from human and animal wastes. E. coli O157:H7 — the strain most dangerous to people — is commonly found in meat, but it has also contaminated water and other types of food.

Once someone has eaten contaminated food, the infection can be passed person to person, by hand-to-mouth contact. The bacteria are most often spread from person to person.

'Very, very difficult to track'

Hilderman said officials will likely never know for sure how the individuals in Arborg were exposed to the bacteria.

"On the one hand, we're happy to see, obviously, that this is not an outbreak, because we know the terrible toll that it can take," he said.

"But by the same token, sporadic cases are very, very difficult to track the exact cause of, because the number of organisms needed to produce an infection is so low and the number of possible transmission settings so great that … linking the infection to a specific transmission setting is very difficult for us."

Last August, 40 cases of E. coli infection were reported in Winnipeg; the majority of the cases were associated with the consumption or preparation of ground beef — more than half of them traced back to a single meat shop.

Hilderman said it has been at least five years since a child died from E. coli in Manitoba.
 
"It's tragic when it happens and it's sort of a stark reminder of how serious these infections can be," he said.