Aflatoxins

Aflatoxicosis is poisoning that results from ingestion of aflatoxins in contaminated food or feed. The aflatoxins are a group of toxic compounds produced by certain strains of the fungi Aspergillus flavus and A. parasiticus . Under favorable conditions of temperature and humidity, these fungi grow on certain foods and feeds, resulting in the production of aflatoxins. The most pronounced contamination has been encountered in tree nuts, peanuts, and other oilseeds, including corn and cottonseed. The major aflatoxins of concern are designated B1, B2, G1, and G2. These toxins are usually found together in various foods and feeds in various proportions; however, aflatoxin B1 is usually predominant and is the most toxic.

In what foods have aflatoxins been found?

In the United States, aflatoxins have been identified in corn and corn products, peanuts and peanut products, cottonseed, milk, and tree nuts such as Brazil nuts, pecans, pistachio nuts, and walnuts. Other grains and nuts are susceptible but less prone to contamination.

What are the symptoms of aflatoxicosis?

The adverse effects of aflatoxins in animals (and presumably in humans) have been categorized in two general forms:

• (Primary) Acute aflatoxicosis is produced when moderate to high levels of aflatoxins are consumed. Specific, acute episodes of disease may include hemorrhage, acute liver damage, edema, alteration in digestion, absorption and/or metabolism of nutrients, and possibly death.
• (Primary) Chronic aflatoxicosis results from ingestion of low to moderate levels of aflatoxins. The effects are usually subclinical and difficult to recognize. Some of the common symptoms are impaired food conversion and slower rates of growth with or without the production of an overt aflatoxin syndrome.

How is aflatoxicosis recognized?

Aflatoxicosis in humans has rarely been reported. However, such cases are not always recognized. Aflatoxicosis may be suspected when a disease outbreak exhibits the following characteristics:

• The cause is not readily identifiable.
• The condition is not transmissible.
• Syndromes may be associated with certain batches of food.
• Treatment with antibiotics or other drugs has little effect.
• The outbreak may be seasonal, i.e., weather conditions may affect mold growth.

How common is aflatoxicosis?

The relative frequency of aflatoxicosis in humans in the United States is not known. No outbreaks have been reported in humans. Sporadic cases have been reported in animals.

Are there complications of aflatoxicosis?

In well-developed countries, aflatoxin contamination rarely occurs in foods at levels that cause acute aflatoxicosis in humans. Studies in Africa and Southeast Asia have revealed an association between cancer incidence and the aflatoxin content of the diet. These studies have not proven a cause-effect relationship, but the evidence suggests an association.

Who is susceptible to aflatoxicosis?

Although humans and animals are susceptible to the effects of acute aflatoxicosis, the chances of human exposure to acute levels of aflatoxin is remote in well-developed countries. In undeveloped countries, human susceptibility can vary with age, health, and level and duration of exposure.