Every year, millions of cases of food poisoning and other gastrointestinal illness around the world have been reported due to such contamination.
The discovery has been credited to Yasunori Tanji and colleagues, who indicated in their report that existing tests do not directly identify E. coli. On the other hand, they detect 'coliform' bacteria, used by health use as indicators for faecal contamination.
However, Coliforms can originate from natural sources, and are not always reliable indicators of faecal contamination. So, there exists direct tests for E. coli, but they take a lot of time and are too complex for general use.
In the new study, the researchers have described a successful use of genetically engineered viruses that infect E. coli to identify a wide range of E. coli strains found in sewage.
Initially the researchers created the viruses to be harmless to E. coli. Later, they viruses were given genes to produce green fluorescent proteins.
The viruses thus produced, revealed the presence of E. coli by lighting up and glowing after infecting the bacteria.
This test uses a fluorescent microscope to detect the glow and the presence of disease-causing bacteria, and takes only a few hours.