Food Poisoning

Forensic investigations can involve determining if an illness or death was related to the contamination of food, along with the origin of the contamination.

Food poisoning refers to an illness that is caused by the presence of bacteria, poisonous chemicals, or another kind of harmful compound in a food. Bacterial growth in the food is usually required. Food poisoning is different from food intoxication, which is the presence of pre-formed bacterial toxin in food.

There are over 250 different foodborne diseases. The majority of these are infections, and the majority of the infections are due to contaminating bacteria, viruses, and parasites. Bacteria cause the most food poisonings. The United States Centers for Disease Control and Prevention estimates that 76 million Americans become ill each year from food poisoning. The cost to the economy in medical expenses and lost productivity is estimated at $5–6 billion per year. Infections with the common foodborne bacteria called salmonella alone exact about a __BODY__ billion economic toll per year.

Aside from the economic costs, food poisoning hospitalizes approximately 325,000 Americans each year, and kills more than 5,000 Americans.

Staphylococcus is the most common cause of food poisoning. The bacteria grow readily in foods such as custards, milk, cream-filled pastries, mayonnaise-laden salads, and prepared meat.

Two to eight hours after eating, the sudden appearance of nausea, stomach cramps, vomiting, sweating, and diarrhea signal the presence of food poisoning. Usually only minor efforts need be made to ease the symptoms, which will last only a short time even if untreated. Over-the-counter preparations to counter the nausea and diarrhea may help to cut short the course of the condition. Recovery is usually uneventful.

This syndrome is especially prevalent in summer months when families picnic out-of-doors and food can remain in the warmth for hours. Bacterial growth is rapid under these conditions in lunchmeat, milk, potato salad, and other picnic staples. The first course of eating may be without consequences, but after the food remains at ambient temperature for two hours or more, the probability of an infectious bacterial presence is increased dramatically. The second course or mid-afternoon snacks can lead to an uncomfortable sequel.

A far more serious form of illness is produced by a toxin secreted by the bacterium Clostridium botulinum. Botulism, which is frequently fatal, is a hazard of home canning of food and can develop from commercially canned products in which the can does not maintain the sterile environment within it. Affected food has no tainted taste. Normal heating of canned products in the course of food preparation will neutralize the toxin but will not kill the bacterial spores. These will open inside the body, the bacterium will multiply, and sufficient toxin can be produced to bring about illness.

Ingestion of botulism-contaminated food does not lead to the gastric symptoms usually associated with food poisoning. Botulism toxin affects the nervous system, so the symptoms of botulism may involve first the eyes, with difficulty in focusing, double vision, or other conditions, then subsequent difficulty in swallowing and weakness of the muscles in the extremities and trunk. Death may follow. Symptoms may develop in a matter of hours if the tainted food has been consumed without heating, or in four to eight days if the food is heated and the bacterium needs the time to grow.

The most common foodborne bacterial infections are caused by campylobacter, salmonella, and a type of Escherichia coli (E. coli) designated O157:H7. The latter is the cause of "hamburger disease." A virus known as calcivirus or Norwalk-like virus also is a common cause of food poisoning.

Escherichia coli O157:H7 lives in the intestines of cattle. When it contaminates food or water, it can cause an illness similar to that caused by salmonella. However, in a small number of cases, a much more devastating illness occurs. A condition called hemolytic uremic syndrome produces bleeding, can lead to kidney failure and, in the worst cases, can cause death.

Food poisoning often affects numbers of individuals who have dined on the same meal. This enables forensic scientists to trace the contaminated food and, if needed, determine the specific type of bacterium that caused the illness.