That’s the conclusion from an extensive feature in Men’s Health on last year’s increase in E. coli O157:H7 in the U.S.

Author Tom Groneberg quotes several folks with their theories for the increase.

Richard Raymond, M.D., the USDA’s undersecretary for food safety, says,

"The amount of product we test that’s positive has gone up about 33 percent this year from the past 3 years. I don’t think it’s that the agency has fallen asleep at the switch. I don’t think it’s that the industry has gotten sloppy. I think it’s the cows."

Specifically, Dr. Raymond cites high corn prices for prompting a switch to cheaper feeds for fattening cattle. "When you change their feed, their intestinal flora change."

T.G. Nagaraja, Ph.D., a professor of microbiology at Kansas State University and the leader of a team of researchers targeting ways to decrease levels of E. coli in cattle before they reach the slaughterhouse, says,

"We found that cattle consuming distiller’s grains as 25 percent of their diet had about a twofold higher incidence of E. coli O157:H7. Our observation is preliminary, but we’ve done three studies that show a positive association between this feed and increased levels of O157."

David Smith, D.V.M., Ph.D., a professor of veterinary and biomedical science at the University of Nebraska, says,

"One factor associated with cattle shedding the E. coli organism is wet and muddy pen conditions. I suspect the slaughterhouses may have had cattle arrive this summer with a higher probability of shedding E. coli, or the cattle had it present on their hides, which led to greater opportunities for ground-beef contamination than during droughts."

Michael Doyle, Ph.D., director of the center for food safety at the University of Georgia and one of the world’s leading authorities on E. coli and other foodborne pathogens, says,

"There is often an increase in bacterial contamination when experienced workers on the slaughter line are replaced with less-experienced workers, such as before and after holidays, and raids this year on illegal slaughterhouse workers by the INS led to replacement with less-experienced line workers."

Doug Powell, Ph.D., an associate professor of pathobiology and scientific director of the International Food Safety Network, says,

"You’re not going to eliminate E. coli O157:H7. Down-line processors have to be operating under the assumption that they’re going to get some E. coli just like we expect consumers to operate under the assumption that they’re going to have some in their product, which is why we tell them to cook it."

So cook that burger. And stick that thermometer in it.