A Guide to Foodborne Pathogenic Microorganisms and Natural Toxins

Microorganisms are just that, microscopic in size. Even though they can only be viewed through a microscope, just a few microbes can multiply and wreak havoc on the human body. There are bacteria that are good for the body. However, for the purposes of this article, focus will center on pathogenic bacteria, viruses, parasites, worms, and other natural toxins, specifically those that are foodborne in nature.

Illnesses arising from food are usually related to improper food handling, inadequate preparation, or storage. For instance, Salmonella spp comes from many sources, but is commonly found in raw eggs, meats that are not cooked thoroughly and even water. Poor hand washing prior to food preparation is another cause of these virulent bacteria. While the body can destroy many bacteria with the gastric acid content found in the stomach, Salmonella spp is hardy and can still be detectible in fecal matter up to one year later. It is closely related to Escherichia group, more commonly referred to as E. coli, another organism that can last inside and outside of the body for long periods of time.

Bacterial infections typically act fast, with gastrointestinal symptoms occurring soon after consumption. Viruses, however, incubate for short periods of time. Hepatitis A, a common virus, is transmitted via the oral-fecal route from contaminated water or food. For example, shellfish taken from polluted water and then consumed carries a high risk of hepatitis A infection. Polluted water can also lead to protozoan infections containing intestinal parasites. The most common protozoan is Giardia, found where there is groundwater contamination or sewage/pipe leaks, resulting in severe gastroenteritis. These protozoans can be small, microscopic parasites living in the human intestines or can result in an infestation of worms from undercooked meat and/or poor sanitation practices.

Other foods have mechanisms to keep others from consuming them. This is particularly true of plants, fungi, and marine life. These are what are known as natural toxins. The skin and organs of a pufferfish, for example, contain a poison known as tetrodotoxin. Tetrodotoxin in small amounts paralyzes the diaphragm, leading to respiratory failure and probable death. Honey intoxication occurs when honey made from the nectar of a toxic rhododendron. Prions are infectious proteins transmitted from contaminated meat to humans, resulting in spongiform encephalopathy, which is incurable and fatal. Mad cow disease is a variant of prion diseases.

Listed below are the most common types of pathogenic agents, grouped by type. These include pathogenic bacteria, enterovirulent Escherichia coli group, parasitic protozoa and worms, viruses, natural toxins, and other pathogenic agents. The links give general information and/or images. These are by no means the only foodborne organisms that can cause disease in humans. Other excellent resources for information regarding foodborne illnesses include the websites for the U.S. Food and Drug Administration (www.fda.gov) and the Centers for Disease Control and Prevention (www.cdc.gov).

PATHOGENIC BACTERIA

ENTEROVIRULENT ESCHERICHIA COLI GROUP (EEC Group)

 PARASITIC PROTOZOA and WORMS

VIRUSES

NATURAL TOXINS

OTHER PATHOGENIC AGENTS