More than 90% of samples taken from Irish rivers show the presence of E. coli, according to a new study from NUI Galway.
And researchers found that the toxic bacteria was also present in bathing waters which pass muster with the EU’s water quality criteria.
Prof Dearbháile Morris and Dr Louise O’Connor at the School of Medicine, NUI Galway, led the study which is due to be presented at this year’s European Congress on Clinical Microbiology and Infectious Diseases.
With European data showing Ireland has had the highest incidence of human infection with Shiga-toxigenic E. coli (STEC) among EU member states for many years — reporting 10 times the EU average in 2017 — the team looked at recreational waters for the presence of the bacteria.
Overall, nearly two thirds of the 75 samples (65%) tested positive for genetic markers of STEC. More than half (56%) of seawater samples were positive, as were three quarters of lake samples.
But just one of 15 river samples tested showed no trace of STEC.
Prof Morris says the high detection rate highlights “the need for further investigation to establish the scale of the problem, not only in Ireland but globally”.
This includes bathing waters in Europe and elsewhere which “are not routinely monitored for the presence of STEC”.