Final answer:
Gastroenteritis from E.coli O157 is transmitted via contaminated food or water and produces a dangerous Shiga toxin that can cause severe symptoms, including bloody diarrhea.
Step-by-step explanation:
Gastroenteritis caused by E.coli O157 is a form of foodborne illness that can be spread through contaminated food or water. This strain of E.coli, known as enterohemorrhagic E. coli (EHEC), is particularly dangerous because it produces a potent toxin known as Shiga toxin or verotoxin.
The Shiga toxin genes were likely acquired from Shigella dysenteriae through horizontal gene transfer, a process in which genetic material is transferred between organisms in a manner other than traditional reproduction. Shiga toxin disrupts protein synthesis within host cells, leading to cellular damage and potentially severe symptoms such as bloody diarrhea. Recognized for causing epidemic outbreaks, E.coli O157:H7 can be fatal and is notorious for contaminating underprocessed meat and produce, resulting in large-scale recalls and significant health concerns.