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Food Poisoning Causes

Food poisoning occurs when you consume contaminated food, water, or other products. Food can become contaminated by bacteria, viruses, or parasites that cause illness.

Contamination can occur at any point in the production, distribution, or preparation of food. Contamination can also happen at home if you don’t follow proper food safety steps while storing, preparing, cooking, serving, and eating food.

Symptoms of Food Poisoning

Food poisoning symptoms vary depending on the type of germ that caused it and how much contamination occurred. Symptoms may include vomiting, diarrhea, nausea and abdominal cramping.

Foodborne illnesses are categorized into five general groups:

Bacteria – Bacteria are some of the most common causes of foodborne illness, including salmonella, E. coli ,and listeria .

Parasites – Parasites, particularly Giardia , are another common cause of foodborne illness.

Viruses – Viruses that commonly result in food poisoning include hepatitis A, Norwalk virus, and rotavirus . These viruses are typically found in raw foods like fresh fruits and vegetables.

Food Chemicals – Chemicals that are naturally occurring or added to foods can also result in foodborne illness, including those found in salty fish, sulfites, and aspartame.

Natural Toxins – While not a common cause of food poisoning, natural toxins do sometimes make people sick. For example, poisonous mushrooms or poisonous fish are natural toxins.

Foodborne Illness Outbreaks

Food poisoning outbreaks occur when many people become sick because of contaminated food or drink. This can be caused by a common food contaminant such as bacteria, virus, or parasite. These outbreaks are not usually isolated events and you will hear about them on the news or from your friends. They can happen at restaurants, catered functions, schools, hospitals, and public events like fairs.

Contaminant Information


Onset of symptomsFoods affected and means of transmission
Campylobacter2 to 5 daysMeat and poultry. Contamination occurs during processing if animal feces contact meat surfaces. Other sources include unpasteurized milk and contaminated water.
Clostridium botulinum12 to 72 hoursHome-canned foods with low acidity, improperly canned commercial foods, smoked or salted fish, potatoes baked in aluminum foil, and other foods kept at warm temperatures for too long.
Clostridium perfringens8 to 16 hoursMeats, stews and gravies. Commonly spread when serving dishes don’t keep food hot enough or food is chilled too slowly.
Escherichia coli (E. coli)1 to 8 daysBeef contaminated with feces during slaughter. Spread mainly by undercooked ground beef. Other sources include unpasteurized milk and apple cider, alfalfa sprouts, and contaminated water.
Giardia lamblia1 to 2 weeksRaw, ready-to-eat produce and contaminated water. Can be spread by an infected food handler.
Hepatitis A28 daysRaw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.
Listeria9 to 48 hoursHot dogs, luncheon meats, unpasteurized milk and cheeses, and unwashed raw produce. Can be spread through contaminated soil and water.
Noroviruses (Norwalk-like viruses)12 to 48 hoursRaw, ready-to-eat produce and shellfish from contaminated water. Can be spread by an infected food handler.
Rotavirus1 to 3 daysRaw, ready-to-eat produce. Can be spread by an infected food handler.
Salmonella1 to 3 daysRaw or contaminated meat, poultry, milk, or egg yolks. Survives inadequate cooking. Can be spread by knives, cutting surfaces or an infected food handler.
Shigella24 to 48 hoursSeafood and raw, ready-to-eat produce. Can be spread by an infected food handler.
Staphylococcus aureus1 to 6 hoursMeats and prepared salads, cream sauces, and cream-filled pastries. Can be spread by hand contact, coughing and sneezing.
Vibrio vulnificus1 to 7 daysRaw oysters and raw or undercooked mussels, clams, and whole scallops. Can be spread through contaminated seawater.

Source: Mayo Clinic

Seek medical attention

If you have a fever over 102 degrees, bloody stool, or other severe symptoms you should seek medical attention immediately.

Legal Assistance

If you are a victim of food poisoning caused by someone else’s negligence you may be entitled to financial compensation through a food poisoning lawsuit.