From tragedy to discovery: the Walkerton Health Study

Winter 2013

The Walkerton water disaster in 2000 took seven lives, made thousands ill, and brought a tightly-knit Ontario community to unwelcomed global prominence. Today more than a decade later, the consequences of one of the worst E. coli outbreaks in history are still being felt. But through the work of a team of dedicated researchers from Lawson Health Research Institute, tragedy is leading to discovery though the landmark Walkerton Health Study.

The study was led by Dr. William Clark and Dr. Amit Garg, both nephrologists at London Health Sciences Centre (LHSC) and scientists with Lawson. Both saw the Walkerton disaster unfold firsthand; as a referral centre LHSC treated some the sickest patients.

The E. coli outbreak in Walkerton was caused by farm runoff that contaminated the town’s well water. At least 2,300 people became ill, but because of limited resources not all cases were diagnosed and recorded. In the months following the outbreak, Dr. Clark saw the need for a one-page screening tool that local physicians could use to assess their patients, as E. coli infection can cause significant long-term health problems and needed to be caught as early as possible.

Dr. Clark arranged a meeting in Walkerton for what he expected to be seven family doctors. To his astonishment, more than 100 people attended. And instead of handing off the screening tool, Dr. Clark was asked to lead a study on the long-term effects of the outbreak.

“I had several major research programs I was running and my first reaction was ‘Not me!’” recalls Dr. Clark. “But they said ‘No, you have to come and do this.’”

Dr. Clark met with Dr. Garg and other colleagues, who all felt an obligation to help the devastated community and also saw a once-in-a-lifetime opportunity to gain knowledge.

“Dr. Clark and I were talking and we said, it really would be invaluable to follow these people to understand the implications of the outbreak,” says Dr. Garg. “Walkerton is unique because it was a single source of bacteria in a well-contained geographical area.”

The scale of the contamination – one of the largest ever recorded - was another consideration.

After securing funding from the provincial Ministry of Health and Long-Term Care, the team presented their plan to the people upon whom its success would depend; the citizens of Walkerton. As Dr. Clark recalls, “In one evening, we met with 1,200 people from Walkerton and outlined what our plans were. We also promised them that we would meet with them once a year to reveal what we had found and what our plans were for the ensuing year.”

Over the next seven years, the study built a database of over 4,000 patients seen annually. “Because of the different types of patients enrolled, we could compare their results. Do people who became ill during the outbreak have different outcomes compared to those who were well during the outbreak?”

One specific benefit for the participants in the study was the early detection and treatment of high blood pressure, which goes undetected in one-third of the general population. Other data gathered suggests that age-related decline in kidney function may be slowed by drinking more water, an unexpected discovery that is currently being verified through another study. “Whenever you’re involved in a study, you find things you would never, ever, anticipate,” says Dr. Clark.

Lawson is sharing the data drawn from the Walkerton Health Study with other scientists as well. “There is the bio-repository and a huge anonymized database that can be accessed by others,” says Dr. Clark. And just as importantly, collection of data goes on. “We had a seven-year follow up, we now have a digital 10-year follow up, and in 20 years another.”

Both Dr. Clark and Dr. Garg go out of their way to express their thanks to the people of Walkerton. “We are very grateful for the people who were willing, in this terrible ordeal, to have their information gathered in a way that we can learn from,” reflects Dr. Garg. “We know a lot more than we did 10 years ago because of their contribution.”

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