Foodborne infection

YERSINIOS1S BY YERSINIA ENTEROCOLITICA

The two most important aspects about the organism and the disease ; that Yer. enterocoliiica is a psichrotroph and can grow at 0° C. and its symptoms include a sh; abdominal pain with fever, mimicking an appendicitis. Yer. pseitdotuberculosis is quite common animals and has been isolated in foods. However, its involvement in foodborne illnesses is confirm Only Yer. enterocolitica and its association in foodborne illnesses are discussed here. Not all strains can produce yersiniosis. Most strains isolated from the environment are nonpathogenic. Pathogenic strains are predominant in pigs. Both the pathogenic and nonpathogenic strains produce an enterotoxin (Yst); thus, toxin production is not directly related to the ability of a strain to cause yersiniosis. Pathogenic strains carry several virulence factors encoded in chromosome (Invasin. AiL, Yst) and in a 70-kb virulence plasmid (YadA, YopH, YopB. YopE. etc.). which are required for adhesion, invasion, and colonization in intestinal epithelial cells and lymph nodes. Only after colonization does the Yst enterotoxin cause fluid secretion in intestine. The pathogenic strains vary in serological characteristics. In the United States, the most common serovar implicated in yersiniosis is 08.

Foods that are incriminated for yersiniosis are generally cycled through refrigeration. Thus the bacterium has to adapt in the human host (37°C) prior to initiating infection. Generally, a high dose (ca. 107 cells) is required for the disease. Once ingested, the bacterium riot binds to M cells in the terminal ilium using adhesion factor. YadA. and is taken up by M cells. Engulfed bacteria are then released from M cells in the basal layer and invade epithelial cells using the Invasin protein and YadA. Bacteria can spread to regional lymph nodes, liver, and spleen. In the intestine, the enterotoxin, Yst, promotes fluid secretion resulting in diarrhea. Young children are more susceptible to foodborne yersiniosis. Symptoms are severe abdominal pain at the lower quadrant of the abdomen mimicking appendicitis, diarrhea, nausea, vomiting, and fever. Symptoms generally appear 24-30 h following consumption of a contaminated food and last 2-3 days. The disease can be fatal in rare cases. Severity of infection is pronounced in immunocompromised hosts as septicemia. pneumonia. meningitis, endocarditis, and so forth.

Because the strains are psychrotrophs. refrigeration cannot be used to control their growth. Good sanitation at all phases of handling and processing and proper heat treatment are important to control the occurrence of yersiniosis. Consumption of raw milk or meat cooked at low temperatures should be avoided. 

FOOD SAFETY: FOOD-BORNE DISEASES

Infectious diseases spread through food or beverages are a common, distressing and sometimes life-threatening problem for millions of people in the United States and around the world. The U.S. Centers for Disease Control and Prevention estimates 76 million people suffer food-borne illnesses each year in the United States, accounting for 325,000 hospitalizations and more than 5,000 deaths.

Food-borne disease is extremely costly. Health experts estimate that the yearly cost of all food-borne diseases in this country is $5 billion to $6 billion in direct medical expenses and lost productivity. Infections with the bacterium Salmonella alone account for $1 billion yearly in direct and indirect medical costs.

There are more than 250 known food-borne diseases. Bacteria cause most cases, followed by viruses and parasites. Natural and manufactured chemicals in food products also can make people sick. Some diseases are caused by toxins (poisons) from the disease-causing organism, others by bodily reactions to the organism itself. People infected with food-borne germs may have no symptoms or develop symptoms ranging from mild intestinal discomfort to severe dehydration and bloody diarrhea.

Recently, public health, agriculture and environmental officials have expressed growing concern over keeping the nation's food and water supply safe from terrorist acts. This bioterrorism threat is being studied by a number of U.S. agencies, including the U.S. Food and Drug Administration, U.S. Department of Agriculture, U.S. Environmental Protection Agency, National Institutes of Health, and the CDC.

This article will describe five food-borne diseases caused by bacteria.

· Botulism

· Campylobacteriosis

· E. coli infection

· Salmonellosis

· Shigellosis

Preventing Food-Borne Diseases

Many times, food-borne diseases are easy to avoid. These are some basic ways to prevent being infected by most food-borne germs. Specific ways to avoid getting sick from food-borne organisms are described in the sections on food-borne diseases:

· Wash hands carefully before preparing food.

· Wash hands, utensils and kitchen surfaces with hot, soapy water after they touch raw meat or poultry.

· Cook beef and beef products thoroughly, especially hamburger.

· Cook poultry and eggs thoroughly.

· Eat cooked food promptly and refrigerate leftovers within two hours after cooking.

· Wash fruits and vegetables thoroughly, especially those that will be eaten raw.

· Drink only pasteurized milk and juices and treated surface water.

· Wash hands carefully after using the bathroom, changing infant diapers, or cleaning up animal feces.