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Presence of E. coli could mean faeces in water supply

Published:06 November 2019

Associate Professor Larelle Fabbro explains what the presence of E. Coli in water samples means to the public.

As one of Queensland’s island resorts responds to a water contamination event causing gastroenteritis in many of its staff and guests, CQUniversity water researchers are shedding light on the common bacteria that has sent the tourism destination into chaos.

Queensland Health and Brisbane City Council are currently investigating a Moreton Island health and safety issue where E. coli has been identified in samples from a Resort’s water supply.

According to CQUniversity water expert Associate Professor Larelle Fabbro said the presence of E. coli is an indicator of faecal contamination, although that bacterium can come from anything from frogs to humans.

“There is obviously a way whereby this organism, and probably other organisms found in faeces, is getting into the system between the groundwater source and the tap.”

She says research by her late colleague Dr Noel Sammon from CQUniversity revealed that even three green tree frogs could be enough to send a reservoir over the contamination limits set for this indicator of human faecal contamination.

“It would be enough to have people racing around trying to work out if anyone was swimming in reservoirs over the weekend and contaminating them.”

However, it is unlikely that frogs are the cause of the gastro cases on Moreton Island.

“There has been no history of strains sourced from frogs causing human illness,” Assoc. Prof. Fabbro explained.

“Normally if E. coli is detected over certain concentrations the probability of the presence of other human pathogens is also increased, hence the term indicator organism.”

She explained that E. coli is a normal inhabitant of the human gastrointestinal tract and does not commonly cause gastroenteritis.

However, there are some pathogenic strains of this organism which may cause diarrhoea and even more serious human illness, especially in children.

“The presence of these pathogenic strains has to be proven and other potential pathogens ruled out.”

The organism can be found in the excreta of everything from frogs to dogs, rats, kangaroos, bats and humans.

“Normally, infections are spread through contaminated food or water.”

Assoc. Prof. Fabbro also warns that the positive E. coli test may just be a diversion, and the cause of the gastro outbreak could be from something else.

“One way of getting a positive test is if the person taking the sample does not have clean hands.

“Then the isolated and cultured strain has to be proven as pathogenic and this has not been done as yet by the sound of things. Chances are that there may be another cause altogether.

“The culture and identification are the next critical steps.”

The most basic techniques preventing spread of E. coli are boiling or disinfecting water prior to consumption.

“This is also the recommendation for water collected from roofs into rainwater tanks.

“Most importantly, to stop the spread from human to human or animals to humans, the simple washing of hands is very effective.”