USA Today reports that the first rule of public health is one most of us learn in kindergarten: Don’t eat poop.

But that’s what the people were eating who were struck down with E. coli in the late summer outbreak tied to bagged spinach, California health officials now say.

There was deadly E. coli O157:H7 in water samples taken on the Salinas Valley ranch where the spinach was grown, in wild pigs that rampaged through the fields, in cattle and calves that grazed nearby, and on cow manure in adjacent pastures, says Kevin Reilly, deputy director of prevention services for the California Department of Health Services.

"It’s not unusual or unexpected that we’d find O157:H7 in the environment where those species exist," Reilly says. Three people died and more than 200 others were sickened in the outbreak that spread to 26 states.