EU research targets microbial contamination
A research project to develop a rapid test for bacterial contamination of drinking water has just started at the University of East Anglia. Led by Professor Paul Hunter, the EU-funded Aquavalens project will carry out field research in both drinking water and food production systems across Europe.
Drinking water can contain harmful bacteria, viruses and single-cell animals and most countries do not routinely test for all these bugs. Instead, scientists usually take a water sample and then place it in a growth dish suitable for so-called indicator gut bacteria such as E. coli.
These bacteria do not cause illness, but if they are present then it indicates that the water has been contaminated with sewage. It can take two days for the usual test to be run, yet contamination in public drinking water might last just a few hours or a day. It is over by the time it has been detected.
Speaking to research portal CommNet, Hunter said: “There are weaknesses in the traditional approach. The biggest is that you can still have infectious pathogens in drinking water when there are no indicator bacteria present.”
Another issue for the researchers is that chlorine can kill indicator organisms, whereas the harmful bugs survive. Hence, testing for the presence of faeces in water makes sense, but the researchers believe it would be even better if routine tests for the bugs which actually cause illness could be carried out, not just indicators.
Hunter’s team plans to develop a test combining genetic techniques and nanotechnology to design a device that could be taken up by major water suppliers. This would flash red for the major microbes causing gastrointestinal illness. It might even distinguish between virulent strains of the one microbe and ones that do no harm.
Around 330,000 cases of water-related disease are reported yearly in Europe according to the World Health Organisation. The offenders are single-celled protozoan animals like Cryptosporidium and Giardia, viruses like norovirus and rotavirus and bacteria like campylobacter, shigella and even salmonella.
Hunter has a particular interest in Cryptosporidium, which is a single-celled organism that can cause outbreaks of stomach illness even in small quantities.
“If you got 100 Crytosporidia in 1,000l, this may well be associated with an outbreak. You can even have outbreaks if there is one in ten litres,” Hunter said.
This is where high-tech biosensors might work. The project is set to trial various technologies to see what works best, dumping any that do not make the grade by year two. The group also hopes to develop a straightforward but quick test for small water supplies.
“If you could go around to a small water supply and take a sample and within a matter of minutes get some indication of whether the supply is polluted or not, I’d be very pleased,” noted Hunter.
Stefan Wuertz, professor of environmental engineering at the University of California, Davis, in the US, is one expert that believes the strategy is likely to bring an improvement in detection.
“New molecular methods may or may not be necessary based on the pathogen target. It is definitely necessary to include monitoring of key pathogens and norovirus is likely the most important one,” he commented. “However, the project is about platforms and reducing timescales of detection. Any such improvement would be good.”
Even companies developing leading edge monitoring systems face a tough challenge, and innovative solutions are few and far between.
Laura Shenkar, water technology expert at Artemis Water Strategy in the US, said: “Tracking new contaminants means that water users have to treat water to address them. In other words, what a drinking water utility doesn't know, it doesn't have to treat.
"At the same time, we have not seen many innovative technologies and designs that would dramatically change the costs of monitoring onsite, with shorter analysis times.”
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