The Centers for Disease Control and Prevention said the illnesses include 20 cases of Hemolytic Uremic Syndrome, 66 hospitalizations and one death.
Federal investigators are combing spinach fields around Monterey, Calif. for clues to the cause of the virulent 0157:H7 E. coli strain, CNN reported.
Possible sources of contamination include water, agricultural practices, improper refrigeration, inadequate washing or any combination of those, said
Dr. David Acheson, chief medical officer for the Food and Drug Administration's Center for Food Safety and Applied Nutrition.
Acheson told CNN that seven farms contracted with Natural Selection Foods LLC, of San Juan Bautista, Calif., have been tested for the bacteria.
The company last week recalled all of its products containing spinach in brands packed with "Best if Used by Dates" of Aug. 17, 2006 through Oct. 1, 2006. A second recall covers products containing spinach in brands sold by River Ranch, of Salinas, Calif. CNN said that company obtained its spinach from Natural Selection.