E. coli O157: the 10% path from bloody diarrhoea to kidney failure

According to WHO the incubation period is 3–8 days, with a median of 3–4 days. It starts with abdominal cramps and diarrhoea, and in some cases progresses to bloody diarrhoea (haemorrhagic colitis). Fever and vomiting may also occur.

What follows is the critical part: WHO states that up to 10% of patients with a STEC infection may develop haemolytic uraemic syndrome (HUS), which has a fatality rate of 3–5%. In addition, 25% of HUS patients suffer complications such as seizure, stroke and coma.

WHO points to raw or undercooked ground meat, raw milk, contaminated vegetables (sprouts, spinach, lettuce) and contaminated water sources.

Minced meat is a special case: in a whole cut, surface bacteria are killed by cooking, but when the meat is minced the surface bacteria are distributed throughout the product. So “rare in the middle” in a minced product means the bacterium has stayed alive.

WHO states that STEC is destroyed by thorough cooking of foods until all parts reach a temperature of 70 °C or higher. “All parts” means the core temperature has to be measured; a browned surface is not evidence.

For those at risk WHO also advises avoiding raw or undercooked meat, raw milk and products made from raw milk: young children, the elderly and immunocompromised people.

Detection of E. coli O157 targets the presence of that specific serotype; the result is present/absent. Enumeration of E. coli is a general indicator of faecal contamination: a rising count says that faecal contamination has entered somewhere in production hygiene, but does not prove that O157 is present.

Enumeration of Enterobacteriaceae is one step broader and is usually monitored as a process hygiene indicator. The three parameters do not substitute for one another; read together they answer “is there a problem, where, and how serious”.