What Causes Food Poisoning

Food poisoning, also known as food-borne illness, is caused by consuming food or beverages contaminated with germs. Food poisoning can be caused by any of the following contaminants:

  • Bacteria.
  • Viruses.
  • Parasites that can live in the intestines.
  • Poisons, also called toxins.
  • Bacteria that carry or make toxins.
  • Molds that make toxins.

A number of these causes are further discussed below:

Bacteria: Many types of bacteria can cause food poisoning, including:

  • Bacillus cereus (bacterium). Symptoms of food poisoning show between 30 minutes to 15 hours. Common sources of infection include foods such as rice, leftovers, sauces, soups, meats and others that have sat out at room temperature too long
  • Campylobacter (bacterium). Symptoms show up between 2 to 5 days. Raw or undercooked poultry, shellfish, unpasteurized milk, and contaminated water.
  • Clostridium botulinum (bacterium). Symptoms show up between 18 to 36 hours. Infants: 3 to 30 days. For infants, common sources of infection include honey or pacifiers dipped in honey. Home-preserved foods including canned foods, fermented fish, fermented beans, alcohol. and commercial canned foods and oils infused with herbs may also cause this.
  • Escherichia coli, commonly called E. coli (bacterium). Usually, symptoms show up between 3 to 4 days. Possibly, 1 to 10 days. Common sources of infection include raw or undercooked meat, unpasteurized milk or juice, soft cheeses from unpasteurized milk, and fresh fruits and vegetables. Contaminated water. Feces of people with E. coli.

Viruses: Viruses such as norovirus, rotavirus, and hepatitis A can also cause food poisoning.

  • Norovirus (virus). Common sources of infection include shellfish and fresh fruits and vegetables. Ready-to-eat foods, such as salads and sandwiches, touched by food handlers with the virus. Also food or water contaminated with vomit or feces of a person with the virus.
  • Rotavirus (virus). Symptoms show up between 18 to 36 hours. Food, water or objects, such as faucet handles or utensils, contaminated with the virus are common sources of infection.
  • Hepatitis A (virus). Symptoms show up between 15 to 50 days. Common sources of infection include raw and under-cooked shellfish, fresh fruits and vegetables, and other uncooked food. Food and water contaminated with human feces. Food handlers who have hepatitis A.

Parasites: Parasites such as Giardia and Cryptosporidium can be present in contaminated food or water and cause food poisoning.

  • Giardia lamblia (parasite). Symptoms show up between 1 to 2 weeks. Food and water contaminated with feces that carry the parasite are common sources of infection. Also food handlers who are carriers of the parasite.

Toxins: Some types of food can produce toxins that cause food poisoning, such as those produced by the bacteria Clostridium botulinum and Staphylococcus aureus.

Note that, Food can become contaminated with these harmful substances at any stage of the food production process, including during farming, processing, transportation, storage, and preparation. Proper food handling and preparation techniques can help prevent food poisoning.