What Are Toxin-Mediated Diseases?

Patient Presentation
A pediatrician’s daughter was talking at dinner about her biology class. “The teacher said different germs can make toxins. I thought that toxins were things like cleaning supplies and chemicals,” she said. “Once the germ like a bacteria gets into your body, how do you think it can make you sick?” her father asked. He explained different ways that organisms can enter the body and affect it, including using her previous knowledge of intracellular structure. “Do you remember the endoplasmic reticulum? It makes the cell’s proteins. It manufactures them. If a toxin stops the manufacturing then the cell dies and the whole organism could die too. I’d have to look it up but I think that is how Shiga toxin works,” he explained.

A poison is a generic term for “a substance with an inherent property that tends to destroy life or impair health.” A toxin is more specific and is “any poison produced by an organism, characterized by antigenicity in certain animals and high molecular weight, and including the bacterial toxins that are the causative agents of tetanus, diphtheria, etc., and such plant and animal toxins as ricin and snake venom.” A toxin does not include those substances that are made synthetically produced. Venom is also a toxin that is used by animals and insects for predation or defense which can cause disease in humans such as snake venom, bee venom, etc.

Toxins can be cell associated (i.e. endotoxin) or secreted (i.e. exotoxin). Other terminology describes the action of the toxin such as leukocidin, enterotoxin or neurotoxin. Some toxins enter cells directly or some are receptor-mediated. Exposure to a toxin does not necessarily cause disease as the exposure may not allow penetration into the body, the concentration of the toxin is not high enough, or the body’s defense systems counteract/neutralize the threat. Vaccines can help the immune system prevent some toxin-mediated diseases.

Learning Point
Common toxin-mediated diseases in humans include:

  • Bacteria
    • Anthrax – Bacillus anthracis, enters body through inhalation, disrupts cellular defense
    • Bacillus fragilis – is part of gut microbiome, enters through gut, can cause sepsis or other organ damage
    • Clostridium
      • Botulism – Clostridium botulinum, caused by eating contaminated food or wounds, causes muscle paralysis
      • Clostridium difficile – caused usually by bacterial overgrowth after antibiotics, causes diarrhea and colitis
      • Clostridium perfingens – makes Shiga toxin, caused by eating contaminated food, causes vomiting and diarrhea
      • Tetanus – Clostridium tetani – caused by contaminated wounds, causes paralysis
    • Diphtheria – Corynebacterium diphtheriae, caused by inhalation and wounds, causes respiratory problems, heart failure, paralysis
    • Escherichia – Escherichia coli O157:H7 or non O157:H7, makes Shiga toxin (i.e. STEC or Shiga toxin E. coli), caused by eating contaminated food, causes vomiting and diarrhea, hemolytic uremia syndrome
    • Pertussis – Bordetella pertussis, enters body through inhalation, causes whooping cough
    • Pseudomonas – Pseudomonas aeroginosa, enters through inhalation or contact with contaminated soil or water, causes severe pneumonia
    • Staphylococcus – Staphylococcus aureus caused by eating contaminated food, wounds, and inhalation, can cause toxic shock syndrome, osteomyelitis, endocarditis, other organ system disease
    • Shigella – Shigella dysenteriae makes Shiga toxin, caused by eating contaminated food or water, severe vomiting and diarrhea
    • Vibriosis – Vibrio cholerae strains O1 and O139 make toxin, caused by eating contaminated food or water, causes severe vomiting, diarrhea, liver disease, sepsis
  • Fungi and Algae
    • Aflatoxin – Aspergillus fungus, contaminates corn but also peanuts, causes acute and chronic liver damage or liver cancer
    • Amanitin – Amanita phalloides, caused by eating this harmful mushroom, causes kidney and liver failure
    • Mycotoxins – various types that affect grain supply
    • Neosaxitoxin and Saxitoxin – cyanobacteria, caused by eating contaminated shellfish
  • Plants
    • Abrin – rosary pea seeds, caused by eating contaminated food, causes cellular protein production malfunction
    • Ricin – castor beans, caused by eating contaminated food, causes cellular protein production malfunction

Questions for Further Discussion
1. What are common poisonings?
2. List other toxins?
3. How common are toxin-mediated diseases in your practice and during what time of year?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews.

Information prescriptions for patients can be found at MedlinePlus for these topics: Botulism and C. diff infections.

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

To view videos related to this topic check YouTube Videos.

Definition of poison, Dictionary.com. http://www.dictionary.com. Accessed January 19, 2021. https://www.dictionary.com/browse/poison

Definition of toxin, Dictionary.com. http://www.dictionary.com. Accessed January 19, 2021. https://www.dictionary.com/browse/toxin

Bacterial Protein Toxins. Accessed January 19, 2021. http://textbookofbacteriology.net/proteintoxins.html

Toxins, National Biomonitoring Program, CDC. Published April 3, 2019. Accessed January 19, 2021. https://www.cdc.gov/biomonitoring/toxins.html

Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa