The problem of food-borne illness has been accelerated by the American appetite for fruits and vegetables — much of it raw, as the market grows for packaged fresh greens.

Americans ate 10 times more spinach in 2005 than in 1970, with much of the growth in ready-to-eat bagged spinach and baby spinach, according to the Department of Agriculture's Economic Research Service.

Americans have increased consumption of all produce — up 25 percent between 1970 and 2004.

Raw produce skips what Linda Harris, an expert on food safety at the University of California-Davis, calls "the kill step." That's cooking that knocks out any pathogens that may have hitched along.

And that's a problem, because fruits and vegetables are more likely to carry disease than they were 30 years ago, says the Centers for Disease Control and Prevention. "In the 1970s, it was two outbreaks a year. In the 1980s, it was seven a year. And in the 1990s, it was 16 a year," says Patricia Griffin, a doctor who studies food-borne and diarrheal illnesses at the CDC. Figures for the past five years are being compiled, she says.

The only thing consumers can do is demand that producers adhere to Good Agricultural Practices, or GAPs, says Douglas Powell, a professor of pathobiology at Kansas State University.

GAPs are a set of principles to guide farmers and processors of fruits and vegetables to produce safe, healthy food. They include steps such as maximizing time between applying manure to fields and harvesting, and keeping domestic animals out of fields during growing and harvest season.

Some of those practices are required by law. But others are encouraged by, not mandated by, the FDA and USDA.

According to the CDC, 5,000 people a year die from food-borne illnesses of all types.

"When you think of the number of animals and the amount of produce that exist in the U.S., it astounds me how seldom we have big problems," says Jan Sargeant, an expert in animal-borne diseases at McMaster University in Canada. "When you hear about a lettuce outbreak, you forget how many times you've actually eaten lettuce without getting sick."