O que é e como evitar a E. Coli?

Depois de duas mortes no RU que se suspeitam relacionadas com a E. Coli, o que é e como se evita?
http://home.bt.com/lifestyle/wellbeing/e-coli-outbreak-what-is-it-and-why-you-should-wash-your-salad-leaves-11364074272760
Citando:
"Also known as VTEC, Escherichia coli O157, is a bacterial infection that can cause severe stomach pain, bloody diarrhoea and kidney failure, according to NHS Choices.
It’s found in the poo and stomachs of cattle and other animals and is caught by eating contaminated food, including raw leafy veg and undercooked meat. Swimming in ponds or streams that are contaminated can also be an issue.
Symptoms generally occur around three to four days after first being infected, but can start anywhere between one to 14 days afterwards and can last up to two weeks.


The NHS says “a small number of people with E. coli O157 infection go on to develop a serious condition called haemolytic uraemic syndrome (HUS). This can sometimes lead to kidney failure and death, although this is rare. The risk of HUS is highest in children aged under five years.”"