Why so many E.coli outbreaks from ground beef?

E.coli enters the marketplace during the slaughtering process but processors are usually blamed.

Following the latest E.coli O157:H7 outbreak -- the 18th in the past three years, U.S. Rep. George Miller, chairman of the House Education and Labor Committee, has requested an investigation into how foods are approved as safe for the U.S. school meal programs, and consumer advocates are pressing for improved standards for testing meat for pathogens.

Ground beef produced by Fairbank Farm in Ashville, New York, was blamed for the outbreak in New York that caused at least two deaths and sickened about 20 people in New England states late last month. Fairbank Farms recalled about 546,000 pounds of fresh ground beef that had been distributed to eight states.

Related: The Weekend Special: E. Coli With Cheese

While E.coli (short for Escherichia coli) can infect many different types of meat products, as well as water and unprocessed milk, ground beef used in hamburgers is especially susceptible to the bacteria. Part of the problem stems from the way beef is processed.

E.coli enters the marketplace during the slaughtering process. Beef cattle may be carrying the E. coli germ in their intestines and if the infected intestinal "pre-excrement" or manure comes in contact with the meat during the slaughtering process, the tainted meat is sent to processors that believe they are receiving USDA inspected and certified meat.

Contrary to the what the stickers on packaged meats might say, the USDA’s Food Safety and Inspection Service inspects samples, not every cow, at slaughterhouses, leaving opportunities for E.coli to evade the inspectors and enter the food supply. A single hamburger can contain meat from four, eight or more cows. It only takes one undetected infected cow to spread the germs throughout the ground meat.

Why mix meat from so many cows? The American Meat Institute says its consumers’ preference for low-fat ground beef. Producers match fat levels of different cows to deliver the “97 percent lean” meat you purchase at the market.

Can you protect yourself and those you cook for against E.coli?

The American Academy of Family Physicians says you can protect yourself from E.coli infection by cooking meat until there is no pink left inside, or to 160 degrees. To take the guesswork out, use a meat thermometer.