E.coli is a misunderstood bacterium as most strains are generally harmless, in fact it actually helps us with digestion and provides essential vitamins like K and B- complex. This commensal bacterium is found in the gut of humans and we excrete up to 100 trillion cells every day.
Humans would not survive without E.coli and other commensal bacteria because they boost our immune system to fight infections.
But not all strains of E.coli are harmless, particularly E.coli O157:H7 and 0104.
The first known E.coli O157 outbreak was reported in the USA in 1982, due to the consumption of undercooked burgers. In the UK the worst outbreaks of this deadly pathogen were in Scotland and Wales, due mainly to cross contamination and failure to comply with food safety laws:
Escherichia Coli 0157 is an extremely tough micro-organism. It can survive for 60 days on a stainless steel surface and the infection dose can be just 10 cells. The onset time is typically 48 hours and the symptoms last around 1-8 days. Illness generally includes abdominal pain, bloody diarrhoea, vomiting and fever. Complications may arise in children and the elderly when toxins from an infection lead to kidney failure (Haemolytic-uraemic syndrome). Luckily with dialysis and blood transfusion most recover.
The intestines of humans and cattle are common sources of E.coli O157. You can also be find it in the natural environment. Contamination can spread via the faecal oral route, food vehicles and water. Beef, especially mince, and other meats are usually the cause of outbreaks. However other foods including spinach, milk and pasteurised fruit juices can cause outbreaks. An outbreak in USA in 2006 lead to 267 illnesses and 3 deaths caused by eating spinach sprayed with irrigation water contaminated with animal faeces.
In June 2011, Germany was the epicenter of the world’s deadliest known E.coli outbreak as more than 3,000 people were ill and 43 killed by a rare strain of E.coli 0104 that was eventually linked to sprouted fenugreek seeds. This cost farmers in excess of £1 billion.
According to the World Health Organisation (WHO) this “super-toxic” strain of the bacteria has never before been seen in people and is more virulent and toxin-producing than others. Consequently, it is affecting everyone, not just particular groups such as children, and the elderly, which is more commonly the case.
A common source of E.coli is the intestinal tract of cattle. The FSA and other food safety agencies around the world are working with farmers and slaughter houses to reduce the risk of contamination by improving current hygiene practice. One study, following E.coli O157 outbreak in Norway, showed cleaning meat carcasses with hot water above 82C reduced contamination by 99%.
The FSA, in response to national concerns over E.coli O157 have produced some sound guidance on reducing the risk of contamination. Advice includes: