PHOENIX - An outbreak of E. coli that made nearly 100 people sick was likely caused by contaminated lettuce, according to the Maricopa County Department of Public Health.
Ninety-four people reported becoming ill after eating at Federico's Mexican Restaurant in Litchfield Park.
The outbreak occurred between July 18 and 30, according to the report.
The findings from samples and a case-control study of 180 people "implicated contaminated lettuce as a probable source of the outbreak and vehicle for the E. coli that caused illness," the report stated.
The source of the bacteria contaminating the lettuce was uncertain, according to the report. It could have been contaminated in the field from manure or irrigation water, during processing, transport, handling or improper storage.
The report says improper washing and preparation at the restaurant may have contributed to the spread of the disease.
The food supplier that provides produce to the Litchfield restaurant also provides food to other Federico's and Valley restaurants.
The public health department made specific recommendations to the restaurant for lettuce handling and storage, as well as hand washing protocols to minimize the risk of E. coli contamination.
In addition, the restaurant performed intensive cleaning and put into place additional lettuce washing procedures to ensure food safety, according to the report.