The CDC estimates that "non-O157 STECs (like O26, O45, 0103, O111, O121, and O145) cause 36,700 illnesses, 1,100 hospitalizations and 30 deaths in America each year."
In speaking about the recent E. coli O145 outbreak linked to romaine lettuce, Patricia M. Griffin, chief of CDC’s Enteric Diseases Epidemiology branch, said it is likely that E. coli O145 has caused previous food poisonings but has gone undetected because only about 5 percent of clinical laboratories are able to detect it. "The fact that we found it now doesn’t mean it wasn’t there before," she said. "The ability to look for the organism in ill people and in outbreaks and food has been increasing. We’re gradually finding more of these organisms."
And, here is the memo to prove it (click image to download):