Enterohaemorrhagic E coli — EHEC — is the type of toxic E. coli that causes gastrointestinal infection with blood in the stool. The group includes the notorious O157:H7 strain: Shiga-toxin-producing bacteria that colonise the gut and attack the intestinal wall, producing bloody diarrhoea, severe cramps, and, in the gravest cases, haemolytic uraemic syndrome — kidney failure striking mainly children and the elderly. Cattle are the reservoir, and infection reaches humans through undercooked beef, unpasteurised milk, contaminated produce, and direct animal contact; the infectious dose is frighteningly small. Food-safety systems treat EHEC as a top-tier hazard — slaughter hygiene, validated cooking temperatures, irrigation-water controls on salad crops. The “enterohaemorrhagic” label describes exactly what it does: bleeding from the gut it has invaded.