Seccret Agent O157: Evolution of a Killer
PBS Frontline
Editor’s note: Stories of this ilk are included in the blog to inform those in our industry how agriculture is being presented to and perceived by the public.
Every pathogen has a story, but the biography of E. coli O157:H7 is especially instructive because it shows how chance favors the prepared germ — and how we are giving certain disease-causing organisms more chances than a rigged roulette wheel. Though E. coli O157:H7 has turned up in unpasteurized apple cider in 1991, 1996, and nearly every year since the Odwalla outbreak [in 1996], it is best known as the agent behind “hamburger disease.” Hamburgers, in fact, are Rolls-Royce conveyances for O157. Think of your next Big Mac as the end product of a vast on-the-hoof assembly line. The story begins on hundreds of feedlots in different states and foreign countries. The animals are shuttled to slaughterhouses, where they become carcasses. The carcasses go to plants that separate meat from bone. The boning plants ship giant bins of meat to hamburger-making plants. The hamburger-making plants combine meat from many different bins to make raw hamburgers. At this point, your burger is more fluid than solid, because ground beef continually mixes and flows as it’s made, its original ingredients indistinguishable. Grinding also multiplies surface area, so that the meat becomes a kind of soup or lab medium for bacteria. Finally, from the hamburger-making plants, these mongrel patties are frozen and sent to restaurants. A single patty may mingle the meat of a hundred different animals from four different countries. Or, looked at from another perspective, a single contaminated carcass shredded for hamburger can pollute eight tons of finished ground beef. Finding the source of contamination becomes impossibly daunting. (Making juice is also like making hamburgers: one bad apple can ruin a huge batch.) In the Jack in the Box outbreak, investigators found that the ground beef from the most likely supplier contained meat from 443 different cattle that had come from farms and auction in six states via five slaughterhouses. As the meat industry consolidates and the size of ground beef lots grows, a single carcass may have even more deadly potential. In 1997, Hudson Foods was forced to recall 25 million pounds of ground beef for this very reason: a small part of one day’s contaminated beef lot was mistakenly mixed with the next day’s, vastly spreading the risk.
