What may be Canada's worst modern outbreak of bacterial infection from contaminated water has killed a toddler, an adult and an elderly woman and left hundreds with bloody diarrhea and in some cases kidney failure.
More are expected to die in Walkerton, a western Ontario farm town of 4,800, and nearby towns. Nearly 20 people were in hospital last night, some gravely ill, and there were unconfirmed reports that another elderly person had died.
Three children were in intensive care -- two in critical condition on kidney-dialysis machines -- at the Children's Hospital of Western Ontario in London, to the south.
"There's never been anything like this in Canada before of this magnitude, never," said Murray McQuigge, the local medical officer of health.
The germ involved is Escherichia coli O157:H7, a deadly strain of the most common bug in the human gut, E. coli. Most E. coli is harmless, but O157:H7 is a cause of what is popularly called hamburger disease, a sometimes lethal food contamination, as well as severe illnesses associated with bad water. It often originates in cattle intestines.
Dr. McQuigge said he believes that the first human exposure occurred between May 12 and May 15. On May 12, parts of the Walkerton area were flooded after a heavy rainstorm.
Most of those affected began to show symptoms, which include fever, severe cramping, bloody diarrhea and vomiting, late last week. Among them were people who passed through Walkerton, including some who ate in the town's restaurants on Mother's Day, May 14.
All schools and daycare centres in Walkerton are closed for the rest of the week as officials try to pinpoint the source of the contamination. Early indications point to a town well.
Walkerton has seven wells to provide water to its residents, but only three were in use at the time of the outbreak. Two of those are nearly 300 feet deep and are several kilometres west of town. One, on the south side of town, is only 65 feet deep and is adjacent to a farm.
Dr. McQuigge said it is not unusual to see up to a dozen E. coli cases, usually involving food contamination, in a small community over a year, but it is unheard of in Canada to have an outbreak of at least 200 cases as a result of drinking-water contamination. "There's been nothing to begin approaching this."
Public-health officials were alerted to the outbreak by a pediatrician in nearby Owen Sound who had two cases of bloody diarrhea referred to him from the South Bruce Grey Health Centre in Walkerton.
Initially, chlorine tests by Walkerton public-utilities workers suggested that the water supply was safe.
But, given the number of people who became ill, Dr. McQuigge issued a bulletin this past Sunday warning residents to boil drinking water. An Ontario Health Ministry analysis of Walkerton's water supply, made public on Tuesday, showed E. coli contamination.
The incubation period for E. coli O157:H7 is from two to eight days. Parents of all young children in the area are being urged to take them for blood tests every two days.
Those who become ill may shed bacteria through their stools for up to three weeks. Hand-washing after using the toilet is essential to curtail the spread of the disease.
Seven to 10 per cent of victims may develop kidney complications. "This is especially a concern in the very young and the elderly," Dr. McQuigge said.
People should not take antibiotics or antidiarrheal medication to fight the bacteria because those who do are more likely to have kidney trouble, he said.
Doctors are largely powerless against the bacteria. All they can do for their patients is prevent dehydration and wait for the illness to run its course.
"Once you've got it, there is nothing we can do to alter the course of it," said Allison McGeer, a microbiologist at Mount Sinai Hospital in Toronto.
The symptoms start with diarrhea and abdominal cramps, and the diarrhea turns a bloody red in a couple of days, she said. For most people, symptoms fade in about four days. Others are admitted to the hospital with a potentially fatal kidney ailment called hemolytic-uremic syndrome.
The bacteria are particularly harmful to young children because "of the immaturity of their immune systems," Dr. McGeer said.
In Walkerton, even those not yet ill fear they will be stricken. Greg McLean and Jane Slosser and their children, seven-month-old Lucas, and Abigael, 3, have been lucky so far.
"We're afraid we've been exposed to it and might have it and we don't know what's going to happen," said Mr. McLean, a Grade 8 teacher at Mother Teresa Catholic School.
The couple are upset that town officials provided insufficient warning and schools were kept open on Tuesday. Dozens of children were obviously sick in class, including several in kindergarten who soiled their pants with diarrhea, they said.
Doctors in the town are so swamped that a call has gone out for help.
Douglas Matsell of the Children's Hospital of Western Ontario, who is treating the hardest-hit children, said one Walkerton doctor saw 75 patients with bloody diarrhea in a day. As a result, an appeal has been made to London hospitals for staff to go to Walkerton during the crisis.
Dr. Matsell said that about 80 childen have bloody diarrhea. He expects that 10 to 15 will develop kidney problems and about half will need dialysis.
The children being treated at the London hospital range in age from 1½ to 15 years and all were perfectly healthy before they came into contact with the bacteria. He said he expects more cases as people who continued to drink contaminated water over the weekend begin to show symptoms.
Walkerton is part of the larger municipality of Brockton, whose mayor, David Thomson, was shaken by news of the deaths.
"It is very distressful," he said. "We're very sympathetic and would like to offer our condolences to those people who have suffered loss as well as those people who are ill. We are doing everything in our power to rectify this problem."
He said the town did everything it could short of going door to door to advise people to boil drinking water. "It happened before anyone was aware of the seriousness of the problem. You know, people were sick before it was known there was a problem."
He advised people not to use tap water "until we're certain that it is potable and it is excellent water. If it takes a week it will be a week, if it takes two weeks it will be two weeks."
Former mayor Jim Bolden said that he believes that the relatively shallow well could be the source of the contamination because it would be exposed to farm runoff after heavy downpours.
Mr. Bolden got out of bed only yesterday after being hit hard by the bacteria. "I've never been sick like this before, never in a hundred years, and I don't ever want to go through it again," he said.
At the local Tim Horton Donuts shop, owner Sue Harrison said the epidemic is a disaster. "I think it's very scary for anyone to think their water is unsafe."
For Ms. Harrison, a 52-year-old grandmother, it has hit especially close to home. All three of her grandchildren, aged 1 to 7, have been ill. The middle child, Liam, 2½, has been the sickest and must have his blood tested every two days to check for signs of kidney damage.
At the doughnut shop, business is off because "people are too scared to go, are sick themselves or are looking after sick children," Ms. Harrison said.
Steve Burns, an engineer advising the municipality, said that the source of the contamination may remain a mystery.
"I would hope that within two or three days we will have looked at all of the likely candidate sources and we will eliminate them as we go along," he said. "There's no guarantee here that we will ever find the exact source of the contamination."
Possible sources include the aquifer from which the town water is drawn, wells and wellheads, construction activity and elevated water-storage basins, he said. He also said data will be checked to see whether town water employees were using sufficient chlorine.
So far, the investigation has yielded no evidence that recent flooding fouled the water, he said. "That's just one of the possibilities."
Meanwhile, the water system has been flushed once with high doses of chlorine and another flush is underway. The town has begun distributing bulk and bottled water at the community centre.
Ontario Environment Minister Dan Newman said ministry officials began their investigation of the contamination on the weekend, but they still had few answers for Walkerton's residents yesterday.
"I don't think we ought to be pointing fingers at anyone or anything at this time," Mr. Newman told reporters. "Our focus must be on on the people of Walkerton, that they have a safe supply of drinking water."
He said the ministry is working to ensure that there is proper chlorination in adjacent communities.
May 12: Storm hits Southern Ontario and runoff, believed to have been contaminated with E. coli, is suspected to have entered the water supply. May 12-15: Residents first exposed to E. coli, probably through drinking water. May 17: First symptoms begin to surface. Patients complain of bloody diarrhea, vomiting, cramps and fever. May 20: Two cases of bloody diarrhea are reported to public-health officials by area pediatrician. The hospital sees more than 20 cases and receives dozens of telephone calls about similar symptoms. May 21: Public-health officials receive the first positive E. coli test and issue a warning advising residents to boil water, despite assurances from the Brockton Public Utilities Commission that the water supply was safe. May 23: Officials report 160 people sought hospital treatment, another 500 called hospitals complaining of similar symptoms over the past few days. The town's water samples test positive for contamination. Dr. Murray McQuigge, medical officer of health with the Bruce-Grey-Owen Sound Health Unit, declares the E. coli outbreak Canada's worst.A toddler dies from complications of E. coli. May 24: An elderly woman and another adult die from complications of E. coli. At least three children were in critical condition, 20 others were being treated in hospital. CP, Staff
HOW E.COLI AFFECTS THE BODY
In North America, the most common strain of E. coli is known as E. coli 0157:H7. This strain appears in the intestines of healthy cattle. HOW DOES THE DISEASE SPREAD? Outbreaks are normally caused by eating undercooked ground beef or drinking unpasteurized milk. It is believed that the recent outbreak in Walkerton, Ont., occurred after storm runoff carried feces into the local water supply. SYMPTOMS Severe and sudden abdominal cramps with watery diarrhea that typically becomes bloody within a couple of days. Body temperature is usually normal but can reach 38.8 degrees Celsius (102 degrees Fahrenheit). Diarrhea lasts about one to eight days. Anemia caused by the breakdown of red blood cells. Kidney failure, strokes, or other complications or nerve or brain damage. These usually occur in the second week of illness. Death may occur. Children and the elderly are the most susceptible. E. coli: Bacteria infects gut, where it produces toxins, which enter the bloodstream. Infection: Toxins destroy red blood cells, causing sudden, potentially fatal, kidney failure. Source: The Merck Manual of Medical Information