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Foodborne Pathogens and Toxins: outbreaks and food recalls
Copyright 2012 - Kris Heeter, Ph.D.
Food can be contaminated by a number of different sources. It seems these days that the number of food recalls due to potential contamination is increasing!
There five main categories of food poisoning:
- Non-infectious Toxins
While bacterial food poisoning has been the highlight of recent food recalls, all types can cause significant discomfort and can be deadly.
Here are some of the more common pathogens and toxins that can cause food poisoning:
Food poisoning causes billions of dollars in health care costs each year. The frequency of occurrence and the number of different bacteria, viruses and parasites that can cause it might surprise you. Research indicates that new mutant bacterial strains that can cause foodborne illness are appearing and these can be up to 100 times more dangerous!
You check out the statistic and interesting discoveries by clicking on the title above.
How many pathogens and toxins can cause foodborne illness?
There are literally thousands of pathogens and toxins that can cause foodborne illnesses.
There are four common types of food poisoning caused by bacteria in the United States, but the list of bacterial pathogens goes beyond these four and is long.
Some examples include (the top four are highlighted):
- Bacillus anthracis (Anthrax)
- Bacillus cereus
- Brucella (an infection known as Brucellosis)
- Campylobacter (an infection known as Campylobacteriosis)
- Vibrio cholerae (a.k.a. Cholera)
- Clostridium botulinum (a.k.a. Botulism)
- Clostridium perfringens
- Helicobacter pylori
- Listeria (an infection known as Listeriosis)
- Shigella (an infection known as Shigellosis)
- Staphylococcus aureus
- Vibrio parahaemolyticus
- Vibrio vulnificus
- Yersinia enterocolitica
Within each genus listed above, there can be several species that can cause food poisoning. In addition, within each species (e.g. E. coli), there can be different subtypes or strains that can cause poisoning.
However, not ALL strains or subtypes of a species, like E. coli, can cause food poisoning. There are other non-poisoning types or strains of E. coli that live within humans and are beneficial.
Examples of parasitic food poisoning include:
- Amebiasis (Entamoeba histolytica infection)
- Anisakiasis (Anisakis infection)
- Ascariasis (Intestinal roundworm infection)
- Cryptosporidiosis (Cryptosporidium infection)
- Cyclosporiasis (Cyclospora infection)
- Cysticercosis (formerly known as Isosporiasis)
- Diphyllobothriasis (Diphyllobothrium infection)
- Giardiasis (Giardia infection)
- Toxoplasmosis (Toxoplasma infection)
- Trichinellosis/Trichinosis (Trichinella infection)
Most of these are a mouthful to verbally say - no pun intended!
Parasites are transmitted by water and food (also by soil and person-to-person). They derive their nourishment and protection from other living hosts, like humans. Parasites can range in size from single-celled organisms to worms easily detectable to the naked eye. Parasites have been known to live in their hosts for years and even decades.
Common examples of viral food poisoning include:
- Hepatitis A
- Hepatitis B
Hepatitis vaccinations are readily available in most developed countries and are typically required when traveling to developing countries and hospitals typically require workers to be vaccinated.
"Norovirus", "Rotavirus", and "Adenovirus" are names given to type or general class of virus - there are several different strains ("serotypes") of noroviruses, rotaviruses, and adenoviruses.
Rotoviruses are a common type of food poisoning. The good news, though, is that there are now two rotavirus vaccines available in the United States, (RotaTeq® and Rotarix®). And, according to the CDC (Centers for Disease Control), rotavirus vaccines have been shown to be safe and effective at preventing the severe diarrhea associated with rotavirus food poisoning.
Norovirus food poisoning is often mistakenly referred to as the "stomach flu" but it should be noted that it is, in fact, not related to the flu (influenza). Influenza or "the flu" is a respiratory illness caused by influenza virus.
Adenovirus is more popularly known as the virus that causes the common cold. As with noro- and roto- viruses, the adenovirus is a name given wide range of viruses. The different strains within this group have varying health effects on humans and animals including: gastroenteritis, conjunctivitis and respiratory problems
Examples of fungal food poisoning:
Whole foods that grow in moist climates or that are stored in humid conditions are more prone to fungal infections. While some species fungi can be beneficial and even eaten (e.g., certain mushrooms), others can be quite toxic.
Fungi that produce toxins that poison food are numerous. One that has made recent headlines is a toxin produce by the genus Aspergillus that can cause "aflatoxicosis". Aflatoxicosis has been shown to cause liver cancer.
Other non-infectious toxins
There are a number of other non-infectious toxins that can cause food poisoning. Lead and other heavy metals are examples.
Mercury and heavy metal poisoning are commonly associated by the public as being in seafood. However, other foods can be contaminated and it's not limited to fresh foods. For example, in August of 2012, a brand of black licorice was recalled for lead poisoning!
The Latest 2012 Recalls
Updated October 10, 2012
Over 200 brands of peanut butter and nut butters have been recalled due to possible Salmonella contamination. These brands were manufactured in a Sunland, Inc. plant that dates back to as early as March 1, 2010.
Food recalls in 2012 and updates
The number of food recalls 2012 is staggering. For those interested, a comprehensive list of recalls can be found through the Food Safety News.
As I write this, a quick peek at the list reveals that there are at least 16 recalls so far for August 2012 in the United States alone.
Some of the foods include:
Smoked Salmon, salad dressings, ready-to-eat meat, poultry, cantaloupe, honeydew, ground beef, cheese, grape tomatoes, raw oysters, apples, cilantro, turkey jerky, bagged mixed greens, romaine lettuce, and mushrooms.
The foods above were recalled most commonly for the potential of the following bacterial contaminaton:
- E. coli
One additional note: Recalls are associated with either the origin of certain foods (contamination that started on a particular farm) or during the processing of foods (contamination occurred in the food processing or specific packaging plant). Therefore, recalls are focused on a subset or brand of food.
Detection of pathogens in food
Recent advances in biotechnology and genome research is making it possible to detect and identify pathogens more readily.
A company called Agilent Technologies, Inc. is collaborating with the University of California (UC Davis campus), the FDA (Food and Drug Administration), and the CDC to establish a database of over 100,000 foodborne pathogen genomes (genomes = DNA sequences or genetic code).
Identifying the genetic code of over 100,000 pathogens responsible for food poisoning and making that information readily available as a public database will speed up the identification of potential pathogens at various points including farms, food processing, and food preparation.
Quicker identification will lead to fewer contaminated foods going to market!