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Biology LibreTexts

15.19B: Aflatoxin Poisoning

  • Page ID
    12313
  • Aflatoxin poisoning is a result of ingestion of aflatoxins produced by Aspergillus that have contaminated a food source.

    Learning Objectives

    • Summarize the causes and effects of alfatoxin poisoning

    Key Points

    • Aspergillus flavus and Aspergillus parasiticus are two commonly known species of Aspergillus that can aflatoxin poisoning.
    • Aflatoxin poisoning can result in either acute aflatoxicosis, which is a result of moderate to high level ingestion; or chronic aflatoxicosis, which results from ingestion of low to moderate levels of aflatoxins.
    • Aspergillus species which cause aflatoxin poisoning are often found in crops in underdeveloped countries, due to lack of detection techniques and inadequate harvesting and storage.

    Key Terms

    • mycotoxins: a substance produced by a mold or fungus.

    Aflatoxins are categorized as mycotoxins that are typically produced by species of Aspergillus. Aflatoxins, although only synthesized by a few Aspergillus species, are considered to be one of the most important mycotoxins identified to date. Both Aspergillus flavus and Aspergillus parasiticus are well known for their production of aflatoxins. Aflatoxins are most commonly transmitted to humans through the diet. Aflatoxins grow on whole grains and contaminate food supplies during processing, storage, or transport when there are favorable conditions for mold growth, specifically for the Aspergillus species.

    image
    Figure: Aspergillus flavus: A species of Aspergillus that causes aflatoxin poisoning.

    Aflatoxin poisoning, or aflatoxicosis, occurs when there is ingestion of aflatoxin contaminated foods. Upon ingestion or exposure to aflatoxin, it is common to see injury to the liver. Aflatoxicosis is a primarily hepatic disease, as the liver is the target organ for this toxin in mammals. Although the liver demonstrates the ability to metabolize the ingested aflatoxins, the intermediate formed is a reactive epoxide or a less harmful hydroxylated form referred to as M1. There have been various studies stating that metabolic activation of aflatoxins is required for the aflatoxin to exert its carcinogenic effects. These metabolites are harmful to the liver and have been implicated in liver cancer development. The aflatoxins produced by these Aspergillus species have been show to produce adducts (altered forms of DNA). These adducts are now used as a diagnostic factor to test for aflatoxin exposure by testing blood and urine.

    Aflatoxin poisoning or aflatoxicosis is rarely diagnosed in developed countries but continues to be an issue in underdeveloped countries. In developed countries, commercial crops are screened for the presence of aflatoxins. However, in underdeveloped or developing countries, screening methods are lacking, or are in the process of being introduced. Interestingly, a rise in homegrown food has been correlated with a slight increase in aflatoxin exposure via diet.

    Aflatoxin poisoning can be diagnosed as either acute or chronic. In cases of acute aflatoxicosis, an individual has been exposed to moderate to high levels of aflatoxins. Acute aflatoxicosis is characterized by symptoms such as hemorrhaging; acute liver damage and issues with digestion; and absorption and metabolism of nutrients. In cases of chronic aflatoxicosis, an individual has been exposed to low to moderate levels of aflatoxins. Chronic aflatoxicosis is characterized by symptoms such as dysfunctional food conversion and slow growth rates.