There is a group of unicellular fungal species that plays a very important role in human nutrition: yeasts. As soon as these fungi find themselves in conditions of oxygen shortage, they begin to transform sugars into alcohol and carbon dioxide. In this way, these fungi are able to obtain energy even in the absence of oxygen, and humans can produce alcoholic beverages, among which beer in particular, but also wine. As early as over 6,000 years ago, the Sumerians exploited fungi to brew beer.
Half a millennium later, the Assyrians learned how to ferment grape juice to turn it into wine. Around the same period, around 3500 BC, the Egyptians began to take advantage of the spontaneous leavening process of flour doughs left exposed to the air in order to obtain a softer and more fragrant bread.
However, the relationship between cereals and fungi is not always idyllic for humans. Ergot, or ergot of rye, shows how thin the boundary is between intoxicating or medicinal substances and poisonous ones. Ergot is the common name given to an ascomycete called Claviceps purpurea, a parasite of grasses, particularly rye, from which the name “ergot of rye” derives. This species is the most studied and well known for its significant effects in contaminating foods made from cereals attacked by this fungus, with serious consequences for people and animals that consume them. These alkaloids, being vasoconstrictors, impair blood circulation and interact with the central nervous system, acting in particular on serotonin receptors. In the past, consuming bread made from flour contaminated by this parasitic fungus led to terrible consequences due to the disease known as ergotism, a dreadful illness known in the Middle Ages as St. Anthony’s fire, holy fire, or burning sickness. Under this term, herpes zoster was also included, since some of its symptoms overlapped with the effects of ergot poisoning.
Ergotism was often fatal and always had devastating effects on the communities affected by it. This disease could occur in two forms: “Ergotismus convulsivus,” characterized by neuroconvulsive symptoms of an epileptic nature, or “Ergotismus gangraenosus,” characterized by gangrene of the extremities up to their mummification. Among the effects of this intoxication were also hallucinations. This led people to associate the disease with the devil or with evil forces, since the cause of these alterations was unknown at the time. For example, some scholars tend to believe that behind the phenomena of witchcraft recorded in late seventeenth-century Salem in the USA there was dietary consumption of ergot of rye, whose alkaloids are resistant even to the high temperatures of bread-baking ovens.
One possible hypothesis regarding the name “St. Anthony’s Fire” is that in Northern Europe, where bread was made from rye and this disease was frequently contracted due to the fungus infecting the rye, sufferers would go on pilgrimage to the shrines of Saint Anthony in Italy. As they traveled southward, they changed their diet by eating wheat bread, which reduced or eliminated the symptoms of intoxication. This effect was attributed to a miracle performed by Saint Anthony. Recent research has called this initial hypothesis into question. In southern Italian regions, the cereals most commonly used for domestic consumption were rye (Secale cereale and, before the second millennium, Secale strictum), barley, and other secondary cereals, especially in Basilicata, Calabria, and the inland areas of Sicily and Puglia. Wheat was destined for export and for the tables of landowners.
Health, veterinary, and agricultural documents attest to the presence of ergotism among poor and marginalized rural communities, and numerous traces of the disease can be found in folklore and popular religiosity. The Antonine Order, responsible for treating these “epidemics,” was widely and extensively present throughout southern Italy from the 13th century onward. Between the 11th and 15th centuries, according to some estimates, this feared disease caused the death of 100,000 people across Europe. It can be assumed that no other fungus in human history has claimed so many victims. Today, strict control of flours prevents the recurrence of such cases; however, cases of poisoning in animals are not uncommon, since animal feed is less strictly monitored.
