Contaminated lettuce is the "probable source" of the E. coli outbreak a few months ago at a Federico's Mexican Food location, according to the county health department.
The Maricopa County Department of Public Health released its report on the investigation of the outbreak, which sickened a total of 94 people, with the main symptom being "bloody diarrhea."
The outbreak came only from the Federico's location in Litchfield Park, and health officials attribute it to a certain kind of E. coli bacteria: E. coli O157. That restaurant location voluntarily closed, but open up again on Mexican Independence Day (in September).
Through a series of tests, the investigators identified lettuce as "by far the most suspect food item."
It is notable that the food supplier that provides produce to this restaurant also provides food to other Federico's locations in Phoenix, as well as other food establishments in the valley. No confirmed cases of illness were recorded from other local restaurants. This point source exposure could have occurred due to contamination at any one of several levels. It could have occurred at the restaurant from an ill food handler, although no employee illnesses were reported from the restaurant during the month of July and this would be a large number of cases to be contracted from a single ill food handler. Cross contamination from another contaminated food source at the restaurant - such as beef, for example - is also a possibility. It is also possible that this restaurant received a small, highly contaminated batch of lettuce that did not go to any other facilities.
A food-safety law firm has since filed a lawsuit against the restaurant's parent company, on behalf of several of the people sickened. One of the men allegedly had what was described as "grossly bloody bouts of diarrhea."
You can see the county health department's report on the next page.