TORONTO - More than a decade after the Walkerton water crisis, scientists who studied the affected residents are still mining their health data to learn as much as they can about the impact of E. coli bacteria.
In a newly released study, they've shown that people in the southwestern Ontario town who came down with acute gastroenteritis from the tainted water were more likely to develop hypertension, kidney problems or have a cardiovascular event, compared with those who were not ill or only mildly ill.
The blood tests, annual physicals and questionnaires for those taking part in the Walkerton Health Study wrapped up a couple years ago, but the report on the long-term risks for the three conditions was published Friday in the prestigious British Medical Journal.
The findings have implications for others who become ill because of the bacteria, said co-author Dr. William Clark, a professor of nephrology and a doctor at London Health Sciences Centre in London, Ont.
"What it means, I think for us as doctors, is that people who get food poisoning from E. coli O157:H7 -- 5,000 to 12,000 people a year in Canada -- they probably should have annual checkups for their blood pressure," he said Thursday from Denver, where he was attending a conference.
"And it would be probably wise to intermittently assess their kidney function, and certainly assess them for cardiac risk factors."
Clark said it's important information because there are treatments to prevent these conditions from progressing.
"So if they get hypertensive, we can treat that so they don't get more accelerated vascular disease. If they have renal impairment and we pick them up early, we can prevent that by giving them certain drugs," he said.
Study participants with acute gastroenteritis were 1.3 times more likely to develop hypertension, 3.4 times more likely to develop structural and renal impairment, and 2.1 times more likely to report a physician diagnosis of a cardiovascular event.
These conditions may not have been caught as early in the Walkerton residents if it hadn't been for the health study, Clark suggested.
"Hypertension is silent, cardiovascular disease only becomes apparent when you have a serious end point, and ... renal disease, you have to lose 85 per cent of your kidney function before you develop symptoms, so these are silent diseases," he said.
"But they're serious ones, and they have a major impact on the health-care system."
There were 1,977 adult participants in the study, including 1,067 who experienced acute gastroenteritis.
The illnesses occurred in May 2000 after heavy rainfall contributed to fecal matter from livestock getting into a drinking water supply that was not adequately chlorinated.
About half the town of 5,000 residents became ill, and seven people died from E. coli poisoning.
Clark paid tribute to those who participated in the study so that scientists could learn more about the health effects.
"We're very grateful to the people of Walkerton for participating so well in the study for such a long period of time," he said.
