Aflatoxin was unmasked by a mystery disease killing English turkeys
In 1960, young turkeys across England were dying of a mystery illness dubbed Turkey X disease. The culprit turned out to be a poison made by a common mould growing on peanut feed. Aflatoxins are now among the most intensively studied fungal toxins in the world, found in everything from maize to spices.
Aflatoxins are cancer-causing, gene-damaging compounds produced mainly by two moulds, Aspergillus flavus, which gave them their name, and Aspergillus parasiticus. These are weedy, widespread fungi living in soil, rotting vegetation, hay and deteriorating grain. They thrive when moisture is at least 7 percent and temperatures sit between 13 and 40 degrees Celsius, best around 27 to 30. The moulds can colonise crops before harvest or in storage, and staples regularly affected include maize, peanuts, rice, wheat, cassava, chillies, cottonseed and tree nuts.
The Turkey X outbreak set off a rapid scientific chase. By 1961 researchers had linked A. flavus to toxic groundnuts, and over the next two years they had identified, isolated and chemically characterised the main B and G compounds. In 1966 related toxins were detected in milk, arising when an animal's liver processes the original poison. Turkeys, it later emerged, are exceptionally vulnerable because their livers convert aflatoxin B1 efficiently into its harmful form while detoxifying it poorly.
No animal is known to be immune to acute poisoning. Adult humans are relatively tolerant and seldom suffer severe aflatoxicosis, but children are hit harder, and the liver is the main target in mammals. Long-term exposure raises cancer risk: toxin fragments bind DNA and seem to favour a particular spot in the p53 gene, a guardian against runaway cell division. A 2004 outbreak in Kenya caused by contaminated maize killed 125 people. There is no specific antidote.
Controls rely on the supply chain: rejecting mouldy grain, testing batches, drying harvests and regulatory limits, first set by the US Food and Drug Administration in 1965. Traditional nixtamalisation, cooking maize in an alkaline solution, sharply lowers the toxin. The most eerie episode came in Poland in 1973, when ten people died after the tomb of King Casimir IV Jagiellon, harbouring aflatoxin-producing moulds, was opened.
Source: Aflatoxin
