TORONTO, Jan. 17 (UPI) -- A leaked report published Thursday blames local water managers in Walkerton, Ontario, for allowing the town's water supply to become infected with E. coli bacteria, causing an epidemic that killed seven and infected 2,300 more in May 2000.
Earlier reports said the water was contaminated when manure from a cattle farm near Walkerton seeped into the ground water or was washed into wells during floods caused by heavy rain. The complete report is to be released Friday.
Canadian scientists said Thursday that E.coli remains a health threat because environmental causes remain unchecked. While there is some research into treatments, there is little incentive for pharmaceutical companies to develop drugs to target the bacteria, experts say.
There is no cure for people who become infected with the bug, Dr. Jim Brunton, a University Health Network expert, told United Press International. When ingested by humans, either by drinking water or eating food that is contaminated, the bacteria cling to the intestines and multiply, releasing large quantities of toxins. The toxins destroy red blood cells and cause bleeding from the colon. The patient becomes feverish and experiences nausea and stomach cramps, accompanied by bloody diarrhea and, in some cases, kidney failure.
Most people "get spontaneously better from it," Brunton said, but some scientific research has been done on possible treatment. According to the Centers for Disease Control and Prevention in Atlanta, antibiotics have not shown to be effective in treating E. coli, and in fact some can make people more sick.
A controversial treatment called therapeutic plasma exchange is sometimes used to treat patients, Brunton said. What that means is, a sick person's plasma is replaced with plasma from a well person.
"Essentially what you're doing is taking away the proteins that are in the blood of the sick person and giving them back proteins which are in the blood of healthy people. It's been proved that it's effective in some related conditions in adults," he said.
Compounds which neutralize E. coli toxins are now on the drawing board, Brunton said. It's easy to make the compounds, but it's not cheap, he said. Since not many people get sick from E. coli ordinarily, there's little use for the compounds, he said.
The Walkerton epidemic was relatively unusual, Brunton said.
"In the average, I might see one or two (E. coli) patients a year at the Toronto General Hospital," Brunton said.
"It's not very common."
A "decoy" treament is also being explored. Such a treatment would bind to the toxin and deactivate it. The decoys, made of sugars, were developed by researchers in Edmonton, Alberta, Brunton said.
Making a vaccine for cattle could be another strategy to keep epidemics at bay, Brunton said.
"What is currently being studied is a vaccine, which in very limited trials, suggested that the amount of bug which the cattle produces, once it's been vaccinated, is very low and it doesn't produce it for very long," Brunton said.
The vaccine still needs more testing in field conditions "such as feed lots and other high-stress areas for cattle, which seem to cause an increased amount of shedding and proliferation of the bug," he added.
The vaccine, a Canadian invention, would have huge applications all over world if successful, but certainly would do well in the Western world, where E.coli has become more of a problem than in developing countries, he said.
Professor Michael Goss, of the University of Guelph, said half of Ontario's wells used for drinking water were contaminated with some form of bacteria, about a third of them with E. coli.
Goss, who did a survey of the province in 1991, says most of the contamination comes from "megafarms," and there still is a danger another outbreak, like that at Walkerton, could occur.
Manure from the "megafarms" was spread over a wide area, Goss said, but some of the contamination also comes from leaky septic tanks, from which the bacteria seeps into ground water.
Brunton said prevention by chlorination of well water "is very, very effective," but if contaminated ground water is used for irrigation, particularly in growing produce such as lettuce, then it becomes another source of infection for people. The food supply also becomes unsafe in places where animal manure is plowed into fields where food is grown, essentially meaning that anything grown in those fields could be infected with E.coli.
