We know that most hypertension diagnoses have no etiology (cause). We also know that in the U.S. escherichia coli 0157:H7 (EColi) infections cause 50,000-120,000 gastroenteric illnesses annually. (commonly known as food poisoning). We also know that there are receptors on the kidney for toxins and exposure can cause both renal and vascular injury causing severe and subtle nephron (kidney cell) loss.
This study followed 1977 adults from Walkerton, Ontario, Canada after the town suffered from a municipal water system contamination with EColi and other bacteria. Acute gastroenteritis was reported by 1067 participants. The researchers followed all the participants of Walkerton annually and excluded people who had hypertension, kidney disease, or cardiovascular disease at the time of the outbreak.
They found that four years after the contamination outbreak, there was a 28% increased risk for hypertension among adults with GI illness. Hypertension was defined as over 140/90. They also found the exposed patients were 3.4 times more likely to develop renal impairment and 2.1 times more likely to have a cardiovascular event (stroke or MI).
In conclusion, this rare oppportunity study showed that acute gastroenteritis from drinking water contaminated with E Coli 0157:H7 was associated with an increased risk for hypertension, renal impairment and self reported cardiovascular disease. Because hypertension and renal impairment are silent, annual blood pressure monitoring and periodic monitoring of renal function is needed for people who have acute gastroenteritis.
What this study does not tell us: We don't know if other bacteria have the same effect or if it was a combination of bacteria that caused it. We don't know if the participants that did not get sick from the drinking water may have been exposed and didn't know it.