Food Poisoning


Food poisoning (foodborne disease or illness) is a gastrointestinal condition that arises after consumption of contaminated food or drink. Usually bacteria or their toxins are main causes of food poisoning but even viruses, parasites or chemicals and natural toxins can cause food poisoning. Food can be contaminated at any stage starting from its production to its storage. In most of the cases food poisoning is self-limiting (resolves without any treatment) but sometimes hospitalization is required for its management.


The nature of the symptoms depends upon the contaminant. Most common presenting features are :

  • Nausea and vomiting
  • Diarrhea (watery or bloody)
  • Fever
  • Generalized weakness
  • Abdominal cramps

Some contaminants causes serious complications requiring urgent medical attention like :

  • Drooping of eye lids
  • Double vision
  • Progressive weakness
  • Difficulty in speech, swallowing, breathing


Contamination of food can occur at any stage starting from harvesting, storage, processing, transportation or even during preparation. Ready-to-eat foods are one of the important sources of food poisoning. Depending upon the nature, onset and type of food consumed the contaminant can be assumed.

  • Staphylococcus: Onset within 1 to 6 hrs. Usually processed meats, potato salads, custards are the source. Source is food handlers harboring the bacteria.
  • Clostridium perfringens: Onset within 8 to 24 hrs. Primarily involved food sources are meat, meat products, and stews. Usually results from problem in heating in lower temperature.
  • Clostridium botulinum: Onset within 12-72 hrs.  Canned foods are the principal source.
  • Shigella: Onset within 24 to 48 hrs. Sources are sea food and pre-cooked meals.
  • Listeria: Onset 9 to 48 hrs. sources are processed and unprocessed food of animal or plant origin (soft cheese, milk, cold salad).
  • Salmonella: Onset within 1 to 3 days. Sources are raw meat, egg yolk, milk products.
  • Vibrio vulnificus: onset within 1 to 7 days. Sea foods are the common source.
  • E. coli: Onset within 1 to 8 days. Main sources are contaminated water, raw vegetables, uncooked beef and milk.

Other contaminants may be due to viruses, fungi and parasites (protozoa and intestinal worms). Any person can suffer from food poisoning. In fact it is a fairly common occurrence and every person may experience one or more episodes in life. However, the symptoms and complications of food poisoning are severe in these instances :

  • Older population
  • Children
  • Pregnant women
  • Cancer, AIDS, renal failure, liver failure patients
  • Any person with low immunity


Treatment depends upon the nature of the contaminant. In healthy adults no specific treatment is usually required. Available treatment modalities are :

  • Fluid and electrolyte replacement due to loss with vomiting and diarrhea. Older people, children and pregnant are more prone to develop dehydration. Intravenous fluid replacement is often preferred to oral replacement if there is severe vomiting.
  • Antibiotics may be needed for certain bacterial and protozoal infections.

Bed rest and having nutritious meals are important measures in managing a case of food poisoning. Oral rehydration solutions (ORS) are often the only source of nutrition while vomiting is present. Once vomiting ceases, a bland diet of solid foods should be consumed even if the diarrhea is persisting.


  • Hand washing before handling food.
  • Proper storage of perishable food in refrigerator.
  • Cooking food at an appropriate temperature.


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