While the food supply is so far relatively safe from terrorist contamination, a lurking natural culprit can cause serious illness and death. According to the Centers for Disease Control and Prevention, bacterial contamination of food causes about 76 million cases of gastrointestinal illness a year. About 325,000 people become sick enough to require hospitalization and more than 1,500 die.
Several types of bacteria are implicated in foodborne illnesses. Salmonella may be found in raw or undercooked eggs, poultry, meat, raw milk and dairy products, and seafood. Food handlers may touch contaminated products and transfer the bacteria to other foods. Infection can cause stomach pain, diarrhea, nausea, fever, chills, and headache. Symptoms generally appear eight to 72 hours after eating contaminated food and last from one to two days.
Listeria monocytogenes is found in ready-to-eat processed foods (such as hot dogs and lunch meat), sausage, cheese, and pasteurized milk. Infection can lead to fever, chills, headache, backache, stomach pain, and diarrhea. Symptoms may develop up to three weeks after infection. The bacteria are somewhat resistant to heat and can survive freezing, drying, and salting.
Campylobacter jejuni is mainly found in raw or undercooked poultry, meat, and shellfish. It can also be found in contaminated water or raw milk. Symptoms generally appear two to five days after infection, and can include abdominal pain, severe diarrhea, vomiting, weakness, fever, headache, and muscle pain. Most patients feel better within seven to ten days.
E. coli (Escherichia coli) is an important cause of foodborne illness. It's found in contaminated water, raw milk, rare or undercooked beef, fruits and vegetables, and unpasteurized apple juice and cider. E. coli can also be passed through person-to-person contact. Within two to five days of infection, patients may experience diarrhea (which may be bloody), nausea, abdominal cramps, tiredness, and weakness. In severe cases, patients develop hemolytic-uremic syndrome (HUS), a condition that causes kidney failure (in the U.S., E. coli is the leading cause of HUS in children). Symptoms last about eight days.
Shigella is a type of bacteria that's found in the human intestinal tract. Infection can cause bloody diarrhea, fever, chills, abdominal pain, and vomiting. Symptoms appear within 12 to 50 hours and last from a few days to two weeks. Infectious disease is typically spread person-to-person through the fecal-oral route (such as not washing hands after using the bathroom) or fecal contamination of food and drinking water. An infected food handler can cause community outbreaks of the illness.
Reducing the Risk of Foodborne Illness
Foodborne illnesses can usually be prevented. Since most bacteria are killed by heat, one of the most important ways to reduce the risk of illness is proper cooking. All meat should be heated to an internal temperature of 180-185 degrees. For whole cuts of meat, such as roasts and steaks, the bacteria reside on the surface. If you like your steaks a little pink or red on the inside, be sure to thoroughly sear or brown the meat to kill harmful bacteria on the outside. Ground meat is a different story. Because it goes through a grinding process, bacteria on the surface gets mixed through all the meat. That means the meat can be contaminated on the inside and out. So hamburgers and ground beef products must be cooked thoroughly. Don't judge a burger by its color. It may look done, but still not be hot enough on the inside to kill all the harmful bacteria. Use a meat thermometer to be sure burgers have reached the right temperature (place the thermometer through the thickest portion of the meat). Once food is cooked, keep it hot. Refrigerate or freeze leftovers within two hours.
Bacteria can also enter foods through cross-contamination. During food preparation, bacteria from one food can be transferred to other surfaces, such as the counter, cutting board, and utensils. Other foods acquire the bacteria when they touch the contaminated surfaces. To prevent cross-contamination of foods, wash hands thoroughly before and after preparing food. Keep raw meats away from other foods. Use hot, soapy water to clean utensils and countertops that have come into contact with raw meat. Clean cutting boards with a solution of one teaspoon bleach added to one quart of water.
When contaminated beef is discovered and reported, the manufacturer is usually required to issue a recall of the product. A number of E. coli outbreaks from contaminated beef have prompted the USDA to issue some new recall guidelines. Under the new rules, a manufacturer will be able to alert consumers and issue a recall in a much more timely fashion.
For information on food-borne illnesses, food safety, and proper food handling:
Food and Drug Administration, Food Information Line, (888) SAFEFOOD.