Foodborne Illnesses: Bacteria

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Foodborne illness often shows itself as flu-like symptoms such as nausea, vomiting, diarrhea or fever. Often people may not recognize that the illness is caused by bacteria or other pathogens on food.

Thousands of types of bacteria are naturally present in our environment. Not all bacteria cause disease in humans. For example, some bacteria are used beneficially in making cheese and yogurt. Bacteria that cause disease are called "pathogens." When certain pathogens enter the food supply, they can cause foodborne illness. Only a few types cause millions of cases of foodborne illness each year.

Most cases of foodborne illness can be prevented. Proper cooking or processing of food controls bacteria. They can grow in just about any food but are fond of protein foods, such as meat, poultry, seafood, eggs and dairy products, as well as high-protein vegetables such as beans and grains.

Bacteria may be present on products when you purchase them. Raw meat, poultry, seafood, and eggs are not sterile. Neither is produce such as lettuce, tomatoes and melons.

Foods, including safely cooked, ready-to-eat foods, can become cross-contaminated with bacteria introduced by raw meat juices or other contaminated products or poor personal hygiene.

Age and physical condition place some persons at higher risk for illnesses than others, no matter what type of bacteria is implicated. Infants, pregnant women, the elderly and people with compromised immune systems are at greatest risk, and may become ill after ingesting only a few bacteria; others may remain symptom-free after ingesting thousands.

Clean: Wash hands and surfaces often. Bacteria can spread throughout the kitchen and get on to cutting boards, knives, sponges and counter tops.

Separate: Don’t cross-contaminate. Cross-contamination is how bacteria spread from one food product to another. This is especially true for raw meat, poultry and seafood. Keep these foods and their juices away from ready-to-eat foods.

Cook: Cook to proper temperatures. Foods are properly cooked when they are heated for a long enough time and at a high enough temperature to kill the harmful bacteria that cause foodborne illnesses.

Chill: Refrigerate promptly because bacteria multiply rapidly between 40 °F and 140 °F. Set the refrigerator at 34 to 40 °F and the freezer unit at 0 °F and occasionally check these temperatures with an appliance thermometer.

Preserve the evidence: Wrap remaining food securely, mark "DANGER" on the packaging and refrigerate it. Save all the packaging materials, such as cans or cartons. Write down the food type, the date and time consumed, and when the onset of symptoms occurred. Save any identical unopened products.

Seek treatment as necessary: Seek medical care immediately if the victim is in an "at-risk" group or if symptoms persist or are severe (such as bloody diarrhea, excessive nausea, vomiting or high temperature). For more information call the Poison Control Center at (800) 922-1117.

Report to authorities: Call your county health department if the suspect food was served at a large gathering, from a restaurant or other food service facility, or if it is a commercial product. Call the United States Department of Agriculture Meat and Poultry Hotline (800) 535-4555 if the suspect food is USDA-inspected and you have all the packaging.

B. cereus can cause two types of illnesses; the diarrheal type and the vomiting type.

Sources: A wide variety of foods including meats, milk, vegetables and fish have been associated with the diarrheal-type food poisoning. The vomiting-type outbreaks have generally been associated with rice products; however, other starchy foods such as potato, pasta and cheese products have also been implicated. Food mixtures such as sauces, puddings, soups, casseroles, pastries and salads have frequently been incriminated in food poisoning outbreaks.

Symptoms: The diarrheal illness results in diarrhea and abdominal cramps occurring within six to 15 hours of eating contaminated food, and may last up to 24 hours. The vomiting-type illness results in nausea and vomiting within three to six hours of eating contaminated food and also lasts about 24 hours.

Prevention: Keep hot foods hot (above 140 °F) or refrigerate them rapidly if they will not be served immediately. Keep cold foods cold (40 °F or below).

Sources: Contaminated water, raw milk, and raw or undercooked meat, poultry or shellfish. The most common source of Campylobacter infections is contaminated poultry meat. People become sick when they eat undercooked chicken or when they inadvertently transfer the organisms from the raw meat or raw meat drippings to their mouth. Cam-pylobacter infections are also acquired from drinking raw, unpasteurized milk, traveling to foreign countries, drinking untreated water from mountain streams or contact with infected dogs and cats.

Symptoms: Fever, headache and muscle pain followed by diarrhea (sometimes bloody), abdominal pain and nausea that appear two to five days after eating; may last seven to 10 days.

Cholera is an acute intestinal infection which occurs in many of the developing countries of Africa, Asia and Latin America, where sanitary conditions are less than optimal. Only a few cases of cholera have occurred in the United States since 1973. Even with foreign travel, the risk of infection to the U.S. traveler is very low, especially for those who follow the usual tourist itineraries and stay in standard accommodations.

Sources: The organism that causes the illness is Vibrio cholerae type O:1. It is spread by ingestion of food or water contaminated directly or indirectly by feces or vomit from infected persons.

Prevention: The best protection is to avoid consuming food or water that may be contaminated with feces or vomit from infected persons. The organism can grow well in some foods, such as rice, but it will not survive in very acidic foods, including carbonated beverages, and is killed by heat.

Sources: Called "the cafeteria germ" because many outbreaks result from food, especially meat dishes, left for long periods in steam tables or at room temperature. The bacteria are destroyed by cooking, but some toxin-producing spores may survive.

Symptoms: Diarrhea and gas pains may appear eight to 24 hours after eating. Symptoms usually last about one day, but less severe symptoms may persist for one to two weeks.

Prevention: Keep hot foods hot (above 140 °F) or refrigerate them rapidly if not served immediately.

SALMONELLA SPECIES (over 1600 types)

Sources: Raw or undercooked eggs, poultry and meat, raw milk and dairy products, and seafood.

Symptoms: Stomach pain, diarrhea, nausea, chills, fever and headache usually appear six to 48 hours after eating and may last one to two days.

Sources: Soft cheese, raw milk, improperly processed ice cream, raw leafy vegetables, meat, and poultry. This organism is unique in that it is able to grow even at refrigerated temperatures. Refrigeration of foods will slow the growth of Listeria, but it will not stop it completely.

Symptoms: Fever, chills, headache, backache, sometimes abdominal pain and diarrhea; 12 hours to three weeks after contaminated food is consumed. However, the very young, the elderly, pregnant women, and those with AIDS or undergoing cancer treatment may later develop a more serious illness (septicemia, meningitis or spontaneous abortion in pregnant women). In otherwise healthy individuals, mild symptoms may disappear in a day or two, but medical attention is required for immunosuppressed individuals who develop the above-mentioned complications

SHIGELLA SPECIES (over 30 types)

Sources: Found in human intestinal tract, and thus contamination is person-to-person by fecal-oral route and fecal contamination of food and water. Most outbreaks result from food, especially salads, prepared and handled by workers using poor personal hygiene.

Symptoms: Diarrhea containing blood and mucus, fever, abdominal cramps, chills and vomiting 12 to 50 hours from ingestion of bacteria symptoms can last a few days to two weeks. Sometimes, no symptoms can be seen.

Prevention: Wash fresh fruits and vegetables thoroughly under running water. Always wash hands well when preparing foods.

Sources: This bacterium is found on humans (skin, infected cuts, pimples, noses and throats) and has been associated with a wide range of foods including meat and meat products, poultry and egg products, salads (such as egg, tuna, potato and macaroni), cream-filled bakery products and pies, sandwich fillings, and milk and dairy products. In general, Staph poisoning often occurs when a food has been handled a great deal (such as the chopping and handling involved in making a salad or sandwich) and is then left at temperatures above refrigeration which allow the bacteria to multiply and produce toxins.

Symptoms: Severe nausea, abdominal cramps, vomiting and diarrhea occur one to six hours after eating. Recovery occurs within two to three days — longer if severe dehydration occurs.

Prevention: Always wash hands well when preparing foods. Keep foods refrigerated.

For information on Clostridium botulinum, request HGIC 3680, Botulism. For information on E. coli, request HGIC 3700, E. coli.