Dr Heather Allison, from the a University of Liverpool’s School of Biological Sciences, has discovered how the food poisoning bug E.Coli 0157 became deadly to humans.
Allison’s team has determined that twenty-three years ago, a harmless gut bacterium called E. coli developed the ability to kill people through food poisoning, bloody diarrhea and kidney failure by becoming infected with a virus. The virus can infect E. coli by recognizing a newly identified but common receptor on the surface of E. coli cells which allows the viruses to gain entry into the bacteria. Once inside, the virus gives new genetic material to the bacterium, providing it with the ability to produce Shiga toxin.

She explains: “Sometime before 1982, an unknown virus that attacks bacteria passed on a part of genetic coding to E. coli that allows some strains to make Shiga toxin. This lethal poison causes the notorious food-borne infection that results in bloody diarrhoea and sometimes kidney failure in people.”

Normally E. coli bacteria live in the intestine and don’t pose any danger, but some varieties can cause fatal food poisoning. The most serious is E. coli O157, which is carried by livestock (mainly cattle), and can enter the human food chain through contaminated meat and inadequate food processing.
Dr Allison suggests that to reduce E. coli infection to avoid undercooked beef and any other food in general that have come into contact with livestock feces and have not been cooked or properly washed. In addition, untreated water (which might be contaminated with livestock feces) should be avoided, and any cooked food that may have come into contact with contaminated, uncooked meat products.