E.coli found at swimming spots with 'good or excellent' water quality

File photo of E. Coli. Ireland consistently has the highest rates of STEC infection in people in the EU. Photo: iStock

A dangerous form of E.coli has been detected in a number of Irish swimming spots that are deemed to have good or excellent water by EU standards, prompting calls from scientists to re-evaluate the quality process.

Researchers from NUI Galway probed 111 samples from 50 locations in Cork, Dublin, and Galway between 2016 and 2019.

The university’s Antimicrobial Resistance and Microbial Ecology (ARME) team said it detected a pathogenic form of E.coli called shiga-toxigenic E.coli (STEC) in a high number of samples.

While most E.coli are relatively harmless, STEC can be life-threatening in some cases. It caused a large outbreak in Europe in 2011, and symptoms include severe stomach cramps, bloody diarrhoea, and vomiting.

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Ireland consistently has the highest rates of STEC infection in people in the EU. Data for 2017 showed that the incidence rate in Ireland was 16.6/100,000 compared with the EU average of 1.6/100,000. Ireland had twice the rate of the next highest European nation.

The ARME paper said: “These organisms can cause very severe intestinal infectious disease in humans and represent a major threat to public health. STEC are particularly hazardous due to their low infectious dose and their ability to survive in the environment.

The most serious complication is haemolytic uraemic syndrome (HUS) which is associated with fragmentation of red blood cells, renal failure and risk of death. 

"Approximately 10% of STEC cases develop HUS, with those most at risk being children under 5 years of age. Those who survive may require long-term renal dialysis or kidney transplant.” 

STEC live in the guts of the likes of cattle, goats, sheep, and deer, with the primary cause of human illness coming from cattle.

ARME researchers said it was detected in 57% of 84 Irish sea waters where samples were collected, as well as 78% of the 27 lake and river samples tested.

This is despite the sea waters being rated as good or excellent quality based on current EU bathing water monitoring criteria.

The research coincided with a call for the public to take part in a survey examining the use of so-called “blue spaces” in Ireland.

The nuigalway.ie/bluespaces survey is part of the four-year PIER project (Public Health Impact of Exposure to antibiotic Resistance in recreational waters), which is funded by the Environmental Protection Agency (EPA).

Principal investigator on the PIER project, Professor Dearbháile Morris, said the findings highlight the need to consider revision of current EU bathing water quality monitoring criteria.

“The most recent bathing water quality data reports that 96% of our identified natural bathing waters meet the minimum required standard. However, our research has revealed the presence of organisms of public health concern in waters designated as of excellent quality in some cases.

“Other ongoing work in PIER will help us to understand the consequences of exposure to organisms in recreational waters, and combined with the findings of the blue spaces survey, it will help to improve water quality and people’s interactions and experiences.” 

Currently, there is no requirement under EU regulations to monitor recreational waters in Europe for the presence of STEC, ARME said.