Ground beef can contain meat from dozens of animals and is particularly prone to bacterial contamination.

Beef processor Tyson Fresh Meats announced late on Friday afternoon that company officials were recalling 40,948 pounds of ground beef that was shipped to 16 states around the U.S. The meat, contaminated with E. coli O157:H7 bacteria, was shipped to 16 states and then re-distributed by local grocery stores.

Tyson Fresh Meats is a division of Tyson Foods, the world's second-largest meat processor, which has 123 processing plants. The contamination was detected at its plant in Dakota City, Nebraska, which shipped the contaminated meat to Alabama, California, Florida, Georgia, Illinois, Indiana, Kentucky, Louisiana, Mississippi, New York, North Carolina, Ohio, South Carolina, Tennessee, West Virginia, and Wisconsin.

Ground beef is contaminated with E. coli more often than any other food, according to figures from the Centers for Disease Control and Prevention, due to all the processing it undergoes. The bacteria live in animals' intestines, and get mixed in with the meat when it's ground, then linger on the meat grinder, in position to contaminate other batches of meat. Add to this setup the fact that most batches of ground meat contain meat from numerous cattle that come from different feedlots, and contamination not only becomes hard to avoid, but difficult to trace, too.

Go Grass-Fed
Feedlots, or "concentrated animal-feeding operations" (aka CAFOs), where thousands of animals are crammed into tight, filthy spaces, do have something to do with the proliferation of E. coli bacteria, but what these animals are fed also plays a big role. Cattle have evolved to eat grass, yet in these feedlots, their primary diet is corn, soy, and other grains. Those grains increase the acidity of the animal's stomachs and gut, making a perfect growing medium for bacteria. However, studies have found that cattle fed only grass have less-acidic stomachs and therefore less E. coli bacteria living in their guts. For help finding the healthiest ground beef, see our guide to buying grass-fed beef.

Know the Symptoms
Symptoms of E. coli O157:H7 infections typically begin three or four days after exposure to the bacteria, but you can get sick as soon as a day or as much as a week later. Common symptoms are diarrhea, which may range from mild and watery to severe and bloody; abdominal cramping, pain, or tenderness; and nausea and vomiting. Infections can turn fatal if someone develops hemolytic uremic syndrome, which leads to kidney failure.

Clean Your Kitchen!
Use soapy water and/or a water-vinegar solution to clean countertops, cutting boards, and other surfaces that come into contact with raw meat. Spray a solution of 1 part white vinegar to 9 parts water onto surfaces, followed by undiluted hydrogen peroxide. Let it sit a few minutes and then wipe it away, or just let it air-dry. A study published in the journal Food Microbiology found this vinegar/hydrogen peroxide mix kills a majority of E. coli, salmonella, shigella, and Listeria bacteria.