Health detectives keep searching for clues for what caused the ecoli outbreak in Wisconsin and across the nation.
No one's actually found ecoli bacteria on a leaf of spinach but there's enough evidence to link the outbreak to the leafy vegetable. UW-Madison food safety expert Steve Ingham says there's no question ecoli is connected to fecal matter and that will likely be the source of the bacteria.
But Ingham says it's not just one cow doing it's business on a patch of spinach. It's a systemic problem and probably an indirect source such as a cattle ranch, miles away, downstream from the spinach farms that use water that's somehow carrying the bacteria.
The sooner investigators can pinpoint the source the quicker the problem can be corrected and people can feel safe about eating produce again. But Ingham says finding all the clues and putting them together takes time.