Notes:

Numerous microbes have been identified as the causative organism involved in food-borne illnesses. Probably the vast majority of food-borne illnesses are related to bacterial species. It is estimated that between 2 and 10 million people have a food-borne illness annually. Most of these people recover without any serious complications, but several people require medical attention. In the past, it was common to hear someone refer to food-borne illnesses as ptomaine poisoning. There is no reason to believe that the bad smelling nitrogen chemicals called ptomaines are responsible for causing illness. Today there are two primary types of food-borne illnesses. Food infections are usually bacterial and caused primarily by gram-negative bacilli. Food intoxications are food-borne illnesses caused primarily by the exotoxins from gram-positive bacteria (both cocci and bacilli).

Because numerous food-borne illnesses go unreported it is difficult to decide if Salmonella, Staphylococcus, or Clostridium causes the most cases of food-borne illnesses each year. Staphylococcus may be the number one cause of food-borne illnesses, but most cases go unreported because of short duration of the symptoms and rapid recovery. The exotoxins or enterotoxins released by Staphylococcus often produce symptoms like cramps, nausea, and vomiting approximately 2-6 hours after eating the "bad food." It is estimated that 30-50% of humans carry Staphylococcus aureua on our skin so food handlers must take extreme caution and attention to prevent contamination of foods, especially during the process of "stuffing foods" like turkeys and cooked pastries. Recently 300 children became infected with Staphylococcus food poisoning from Easter eggs that had been boiled (weakened the shells) and allowed to stay at room temperature for 3 days. Other outbreaks include 64 wedding guests in Deleware who ate contaminated chicken salad and a multi-city outbreak related to imported mushrooms.

Clostridium perfringens and C. botulinum are two species known to cause food-borne illnesses. C.perfringens is found in approximately 50% of red meats. First identified in the 1960s, C.perfringens may presently be one of the top three bacteria involved in food-borne illnesses. This bacterium is found in our intestines but does not reach large numbers. Usually about 7-15 (sometimes up to 24 hours) after eating "bad meat,' the toxins begin to alter the permeability of the intestinal wall leading to cramps and diarrhea. Contaminated burritos in California recently caused 181 people to develop the symptoms of C.perfringens intoxication. Clostridium botulinum is the most fatal type of food poisoning. We call it botulism; and the dangerous neurotoxin must be destroyed by properly cooking the food (80 degrees Centigrade for 10 minutes). It is estimated that one milligram of botulinum toxin would kill one million guinea pigs. The toxin binds to synaptic membranes at the nerve-muscle junction and is fatal unless you quickly administer an antitoxin. The symptoms which include breathing difficulty usually occur 12-36 hours after ingesting the toxins. A recent outbreak in California was related to left-over stew; other outbreaks have been traced to foods like canned beans and peas, smoked fish and meat, and Japanese suchi (raw fish) which were used in uncooked salads or sandwiches. Infant botulism has occurred in infants under 6 month of age, on antibiotic therapy, and given raw honey which contained the endospores of C.botulinum.

Salmonella food infection results from contaminated food handlers and products made from uncooked eggs. Properly cooked foods are usually safe if consumed immediately or cooled quickly to 4 degrees Centigrade or less. Salmonella has produced symptoms in 6-12 hours; but often symptoms begin several days (1-3) after eating the contaminated food. S.typhi causes typhoid fever; and you may be familiar with typhoid Mary. Mary Mallon was a cook who carried the bacillus and caused the deaths of several people. The New York state health inspector had Mary Mallon imprisoned when she refused to have her gall bladder removed or stop working as a cook. It is known that the gallbladder harbors the Salmonella organism. Perhaps as many as 20,000 cases of food-borne gastroenteritis related to the numerous species of Salmonella occur annually in the world (some microbiologists believe there are up to 40,000 cases in the US alone each year); but only 400 cases of actual typhoid fever are reported to the CDC each year. Consequently, the typhoid fever vaccine is used only in circumstances where an exposure or outbreak may be expected. The food most often related to salmonellosis is uncooked eggs used in ice cream, meringues, cream cakes, eggnog, and other egg products. The outbreak in a midwestern ice-cream plant in the mid-1990s was traced to inadequate cleaning of the truck used to transport raw eggs and also pastuerized products used in the making of the ice-cream. An outbreak of salmonellosis was the result of contaminated sandwiches served at a restaruant in Washington. Still other outbreaks included about 5800 cases related to contaminated milk in the Midwest US and 200 children who ate chicken at an Oklahoma school. It was estimated that 10% of the Salmonella outbreaks were related to children handling small pets, so in 1975 the sale of small turtles, chick, and ducklings was prohibited.

Several strains of E.coli have been the cause of food-borne illnesses.s One strain is related to 250 deaths per year and at least 20,000 reported cases. This strain (E.coli 0157:H7) is most often associated with contaminated meat; and a recent outbreak in four western states was traced to undercookded hamburgers made from meat contaminated at the slaughter house. This strain causes diarrhea and potential kidney failure in children. HUS (hemolytic uremic syndrome) is potentially fatal in children and all cases must be reported in the United States. Other strains of E. coli may be related to symptoms like minor cramps to serious diarrhea. Infantile diarrhea may be the single greatest cause of death among children. In crowded areas of the world where sanitary facilites are poor, up to 15-25% of children may die from diarrhea. Infantile diarrhea is also caused by a rotavirus resuting in the deaths of 1.0-1.5 million children annually in the world. It is important ot use non-contaminated water in preparing formula and rapidly replace body fluids and electrolytes in infected children. Traveler's diarrhea is a very common infection found in North Americans traveling around the world (up to 50% of travelers). Some of these diarrheal infections are caused by exotic protozoans; but E.coli is a common pathogen that causes the diarrhea, fever, and vomiting. Contaminated water supplies and uncooked foods are the primary carriers of the E.coli. The symptoms may occur within 5 days; and the E.coli (and enterotoxins) need to be eliminated from the intestinal tract. Over-the-counter preparations (like Lomotil) may stop the diarrhea but keep the E. coli in the intestine and may not be as effective as Pepto-Bismol which counteracts the toxin. Out breaks of E.coli enteritis have been traced to ice cubes used to make cocktails; and the lack of food and stomach acids do not allow the time to kill E.coli in the stomach before the "melted ice" goes to the intestine.

Numerous other microbes have been associated with food-borne illnesses. Among the bacteria are Campylobacter (perhaps the #1 microbe related to high fever and cramps following exposure to non-chlorinated water and uncooked poultry), Vibrio (associated with scombroid or shellfish poisoning, such as uncooked shrimp), Bacillus (undercooked macaroni and cheese, rice), Listeria (milk), and Francisella (handling contaminated rabbits). Food-borne illnesses have been associated with fecal contamination of food and water by the Hepatitis-A virus. Symptoms including jaundice and later liver damage may occur 2 weeks after exposure to contaminated food. This makes identification of the virus contaminated food very difficult. Only raw shellfish is a food problem because heating destroys the hepatitis virus. Fungi with their mycotoxins or aflotoxins have been associated with food-borne illnesses. Most molds are macroscopic so human illnesses are rare; however, you must also remember nto to feed your pets and other animals "moldy foods. Trichinella is a roundworm found in some pork, bear, dog, rat, and whale muscle. Incidence of trichinosis is about 200,000 new cases per year in the United States. Ethnic customs of eating rare pork (tasting raw homemade sausage for seasoning) or wild animals (bear is related to 1/3 of US cases of trichinosis) seem to be the major sources of Trichinella infections. Initial flu-like symptoms with diarrhea and abdominal pain may be followed by intense muscle and joint pain. Heart and brain infestations are rare and symptoms eventually disappear; but one woman did die within 48 hours after eating infected meat.