So essentially - the problem is that spinach is being grown using very contaminated water (esp. in California - not as much in Florida).
Spinach: What you should know
Q: The Centers for Disease Control and Prevention and the Food and Drug Administration recommend discarding bagged salad mixes that contain spinach, and not eating fresh spinach in its raw state for now. Is cooked spinach safe?
A: According to Tom Skinner, a CDC spokesman in Atlanta, fresh spinach should not be consumed raw. "We think that cooking to 160 degrees for 15 seconds will do what needs to be done to make it safe, but that's 160 degrees all the way through and it's hard to take the temperature of a leaf of spinach. For now, use frozen packaged spinach and cook it as directed." Microwaving can't guarantee a safe temperature.
Q: Will washing take away the E. coli?
A: "This is a very hardy bacteria," Skinner says. "Thoroughly washing fresh produce is always a good thing to do, but cook it properly too."
Q: So E. coli isn't just dangerous in meat or dairy products?
A: "These outbreaks are usually associated with undercooked meat, but we have seen a number of outbreaks related to produce," Skinner says.
Q: What other type of produce poses an E. coli risk?
A: Any produce that is irrigated. "It's not the produce itself, it's how it's grown, harvested and packed," Skinner says.
From the LA Times:
E. Coli Pervades Harvest Area
Salinas Valley waterways are known to carry the bacteria that poisoned at least 145 people and killed one who ate tainted spinach.
September 21, 2006
The bacterium that has sickened people across the nation and forced growers to destroy spinach crops is so pervasive in the Salinas Valley that virtually every waterway there violates national standards.
"There are many sources of water coming into the watershed, and I guarantee you that they all have generic E. coli," and many carry the deadly E. coli strain linked to food poisonings, said Christopher Rose, an environmental scientist at the state's Central Coast Regional Water Quality Control Board, which tests the region's waterways.
Federal officials said Wednesday they are focusing on nine fields in San Benito, Santa Clara and Monterey counties as possible sources of the bacteria-contaminated spinach that killed one woman and sickened at least 145 others in 23 states.
Investigators also announced that spinach found in the refrigerator of a New Mexico resident who became ill tested positive for E. coli 0157:H7, the dangerous bacteria strain responsible for the outbreak. The finding confirmed suspicions that the tainted spinach originated from California's Central Coast, where it was packaged by Natural Selection Foods under the Dole label....
The O157:H7 strain was first recognized as a cause of illness during a 1982 outbreak traced to fast food hamburgers. But its prevalence in most regions is unknown because there is no EPA requirement to test for it in waterways, wells or irrigation water, Kemery said.
After food poisoning outbreaks several years ago, regional water officials stepped up sampling and added analysis for the deadly strain in the Salinas watershed, finding the bacteria in several waterways next to areas where livestock graze.
E. coli is a national problem, but it is especially severe in livestock areas. A single cow can shed as much as 100 billion fecal bacteria per day. The food-poisoning outbreak could pit vegetable growers against livestock owners, both economic powerhouses in the state.
Monterey County's spinach fields are downstream of the Gabilan Mountains, where beef cattle, dairy cows and horses graze. En route to the Salinas River, many tributaries flow through the livestock areas, picking up bacteria. The water then flows through the low-lying valley where vegetables are grown.
Cattle and other livestock graze near the banks of the creeks, and their manure can easily contaminate the water with millions of E. coli organisms. "In some areas, grazing has resulted in manure lining the banks of channels of tributaries to the Salinas River," a June report by the Central Coast water board stated.