Food Poisoning Causes and Symptoms

Cases of food poisoning, although usually mild, do have the potential to be deadly, depending on the pathogen as well as the age and immune functioning of the person afflicted. Other than known occurrences of mass exposure, the incidence of food poisoning is difficult to tally, since many people who become ill, have mild or quickly resolving symptoms, and do not seek out medical treatment.

Infectious Versus Toxic Causes of Food Poisoning

The types of food poisoning can be divided into two main categories: those caused by infectious agents versus toxic agents. Infectious agents are things like viruses, bacteria, and parasites, whereas toxic agents include poisonous mushrooms, exotic foods that can contain toxins when not prepared properly, and pesticides on fruits and vegetables.

Food Poisoning: The Fecal Oral Route

Food poisoning from infectious agents typically occurs via the fecal-oral route, when food is contaminated with bacteria or viruses present in feces. Vegetables and fruits can harbor harmful microbes if they are watered with fecally-contaminated water, or touched by contaminated hands. Food handlers who do not wash their hands after using the bathroom, or even browsing consumers handling produce, can transfer pathogens onto fresh food items. Flies are also vectors in the spread pathogenic microbes, when the insects feast on feces and then on food.

Most Food Contains Some Bacteria

Bacteria are everywhere. There are very few food items that are sterile, other than those that have undergone the canning process. Animal-based foods, in particular, are naturally full of microbes. Dairy products are pasteurized so that potentially harmful bacteria are killed. Meat is cooked to destroy these microbes, and sufficient cooking does solve the problem. Foods from animal sources become dangerous when carelessly prepared, undercooked or insufficiently refrigerated. Lack of refrigeration does not contaminate food, but food that is stored at a temperature that's not cold enough can allow for the growth of microbes that, when present in low numbers, would otherwise not cause illness.

Symptoms of Food Poisoning

Symptoms of food poisoning can vary, based on the cause, the amount of tainted food consumed and the general health of the individual. The onset of symptoms usually occurs suddenly, within 48 hours after consuming contaminated food or liquid.

The most common symptoms of food poisoning include:* Nausea and vomiting
* Abdominal cramping
* Diarrhea

Other possible symptoms (depending on the type of pathogen) may include:* Fever
* Chills
* Bloody stool
* Nervous system damage

For more specifics on bacterial food poisoning, see the articles "Prevention and Treatment of Food Poisoning" and "Shigella Food Poisoning".

Resources

Bauman, R. (2004) Microbiology. Pearson Benjamin Cummings

eMedicine Health: Food Poisoning

WebMD: The Basics About Food Poisoning

Please note: The information in this article is not to be followed as medical advice, diagnosis or treatment. Please consult with a physician or primary health practitioner for information regarding personal health and necessary treatments. This article was originally published in Suite101 online magazine.