From the New York Times October 7, 2006 by Libby Sander:

“There were probably people like this around the country getting sick, but their sicknesses antedated the realization that we had a problem,” Dr.
Safranek said. “In late August this really hadn’t come to light as a nationwide outbreak.”

Public health officials believe that for every E. coli case reported, 20 go unreported, said Dr. Patricia Griffin, a microbiologist and a top epidemiologist of the federal Centers for Disease Control and Prevention,
which on Friday confirmed that the death was linked to the same E. coli

“In this outbreak, as in most outbreaks,” Dr. Griffin said, “there were many more people ill who, for one reason or another, were not confirmed as having the illness.”

She said that there could be other deaths linked to the outbreak, but that it was impossible to determine how many.

Interesting quote – If correct, the true numbers in this outbreak might be 20 times the nearly 200 reported – a stagering 4,000 people – Jack in the Box’s final numbers were just over 650 and 4 deaths