What are the most common causes of foodborne infections?

Doreen Rodo
Nutrition & Dietetics

There are many causes of food borne illness, but some of the most common are:

  • Food not being stored or cooked to the appropriate temperature
  • Cross-contamination-which is touching an item like raw chicken with a utensil and then tossing a salad with the same utensil
  • Poor hand washing
  • Touching open sores and then touching food
  • Food employees coming to work sick


Michael T. Murray, ND
Naturopathic Medicine

The most common causes of food borne infections are the bacteria Campylobacter, Salmonella, and E. coli O157:H7, and the caliciviruses, also known as the Norwalk and Norwalk-like viruses. Undercooked meat and poultry, raw eggs, unpasteurized milk, and raw shellfish are the most common sources of these organisms.

Campylobacter is a bacterial pathogen that causes fever, diarrhea, and abdominal cramps. It is the most commonly identified bacterial cause of diarrheal illness in the world. This bacterium lives in the intestines of healthy birds, and most raw poultry meat has Campylobacter on it. Undercooked chicken or other food that has been contaminated with juices dripping from raw chicken is the most frequent source of this infection. Salmonella is another bacterium that is widespread in the intestines of birds, reptiles, and mammals. It can spread to humans through a variety of foods of animal origin. The illness it causes, salmonellosis, typically includes fever, diarrhea, and abdominal cramps. In persons with poor underlying health or weakened immune systems, it can invade the bloodstream and cause life-threatening infections.

E. coli O157:H7 is a bacterial pathogen that has a reservoir in cattle and similar animals. Human illness typically follows consumption of food or water that has been contaminated with even microscopic amounts of cow feces. The illness it causes is often severe and typically provokes bloody diarrhea and painful abdominal cramps, without much fever. In three to five percent of cases, a complication called hemolytic uremic syndrome (HUS) can occur several weeks after the initial symptoms. This severe complication includes temporary anemia, profuse bleeding, and kidney failure.

Calicivirus, or Norwalk-like virus, is an extremely common cause of food borne illness, though it is rarely diagnosed because the laboratory test is not widely available. It causes an acute gastrointestinal illness, usually with more vomiting than diarrhea. It usually resolves within two days. Unlike many food borne pathogens that have animal reservoirs, it is believed that Norwalk-like viruses spread primarily from one infected person to another. Infected kitchen workers can contaminate a salad or sandwich as they prepare it, if they have the virus on their hands. Infected fishermen, for instance, have contaminated oysters as they harvested them.
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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.