Data from the E. coli O157:H7 outbreak in Walkerton Canada has been mined time and again by researchers studying the long-term effects of E. coli infection, including its tendency to cause or exacerbate motility problems in the gastrointestinal tract like IBS. A new study in the British Journal of Medicine finds that outbreak cases who had severe cases of gastroenteritis were at higher long-term risk than other people of developing hypertension, renal impairment and cardiovascular disease.
A prospective cohort study was set up in Walkerton, Ontario, Canada to investigate any long-term health problems following contamination of the town’s water supply in May 2000 with E. coli O157:H7 and Campylobacter.
Researchers recruited 1977 adult participants of whom almost all (99%) said they had drunk the contaminated water. Of these, 1067 (54%) had had acute gastroenteritis, and 378 sought medical attention.
Participants were followed up annually, with physical examination and laboratory assessment. This included height, weight, blood pressure, serum creatinine concentration, random (spot) urine analysis for albumin: creatinine ratio; in some years fasting serum glucose measurement, oral glucose tolerance testing and 24-hour urine collection were also done.
People who had had acute gastroenteritis during the E. coli outbreak were 1.3 times more likely to develop hypertension, 3.4 times more likely to develop renal impairment and 2.1 times more likely to have a cardiovascular event such as a heart attack or stroke, compared with people who had not been ill or only mildly ill. We have certainlly seen these risks for people who develop Hemolytic Uremic Syndrome (HUS), but not for more mild illnesses.
“Our findings underline the need for following up individual cases of food or water poisoning by E. coli O157:H7 to prevent or reduce silent progressive vascular injury.” They suggest that annual monitoring of blood pressure and periodic monitoring of renal function may be warranted. They add: “These long term consequences emphasize the importance of ensuring safe food and water supply as a cornerstone of public health.”