The ascomycete Claviceps purpurea is the causative agent of ergotism. It grows chiefly on rye. Another twenty or so gramineous species (cereals and grasses) can also be infected. Nowadays, rye is cultivated on a much smaller scale than wheat. Some years ago, rye (Secale cereale) was successfully crossed with wheat (Tricicum sp.), creating a new crop called triticale. These hexaploid and octaploid hybrids are robust and have a high yield. The susceptibility of these new plants to ergot is not well-known.

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In earlier years there would sometimes be a widespread ergot problem, while at other times it was virtually nonexistent. Warm, wet springs and summers stimulate the growth of Claviceps purpurea. The influence of weather conditions can be explained by examination of the different life stages of the fungus. The fungus grows into a rye kernel and subsequently appears as a thin, purple-black, cock’s spur-like spikelet protruding from the mature head of rye (Fr. ergot = cock’s spur). This structure is a sclerotium. When the rye ripens, sclerotia from the infected crop fall on the soil and absorb moisture. The fungus survives through the winter in this form. The following spring, the sclerotia present on the soil surface produce a mass of fine, threadlike filaments with a round club-like tip (Claviceps; Lat. clava = key; ceps = club). Numerous asci – minute saclike structures each containing eight ascospores formed following sexual reproduction – develop in the tip. These spores – one million per sclerotium – are dispersed by the wind. Dry windy weather helps in the dispersion of the spores. Rye is only susceptible to infection during the first few days of flowering. When the spores come into contact with the style of the tiny rye flower and if moisture is present (dew, mist, raindrops) a mycelium develops within a week, accompanied by the formation of asexual conidiospores. This is called the sphacelia stage. The fungus produces a sticky exudate (a kind of ‘honey dew’) that attracts insects such as flies and beetles. As they visit each plant they carry the conidiospores to other rye flowers, causing new infections with each visit.

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Human disease can occur when rye contains 1% ergot. An ergot content of 2% can result in epidemics and at 7% there is a high (dose dependent) mortality rate.

In medieval times, ergotism is known to have occurred on a large scale in some regions of Europe. In 857, for example, there was an epidemic in Germany characterized by necrosis of limbs and culminating in death. In 944, some 40,000 people in the south of France died from ergot poisoning. The so-called ‘Plague of Fire’ in Paris (945) was almost certainly caused by ergot. The symptoms were also called Holy Fire, St. Anthony's Fire and St. Vitus’ dance. Between 837 and 1347, some fifty epidemics were recorded in Central Europe. Hospitals dedicated to St. Anthony took care of the patients afflicted with ergotism, many of whom recovered after rye bread was removed from their diet. It was a common belief that the symptoms were caused by witchcraft. The main crop and staple cereal in the witchcraft areas was rye. In some years, there were abnormally high numbers of witchcraft trials, persecution and executions. In years when many witch persecution trials were held, the price of rye was high (poor growing conditions for rye but good conditions for Claviceps). In the Salem witchcraft trial of 1692-1693 (USA), entire communities in and around Salem Village had symptoms of ergotism (including some of the animals). Extreme convulsions, hallucinations and a burning skin sensation were the most obvious symptoms. In 1670, a French physician, Dr Thuillier, suggested that food could play a role in this disorder. He noticed that there were fewer outbreaks of ergotism in the towns than in the countryside. There were considerably fewer cases among the rich. Sometimes only one member of the family fell ill, while in other households everyone was afflicted. The disease did not spread to neighbouring families. People who had lived in isolation for months (and who therefore ran little risk of infection) could likewise suddenly become ill. He suspected that Claviceps was the causative agent but he was never able to provide formal proof. Later, others showed that when ergot was fed to animals, they died. In August 1951, in the small French town of Pont St-Esprit on the banks of the River Rhône (Provence) more than a hundred people were poisoned and several died as a result. The local doctor first saw two patients with intense pain in their lower abdomen, low body temperatures and cold fingertips, incoherent babbling and hallucinations. The next day there was a third patient and after contacting his colleagues, twenty similar cases were discovered. Two days later there were even more cases. Patients had to be tied to their beds. Rumours soon spread that witchcraft was involved, but subsequent investigation showed that the symptoms had been caused by ergotism. All the victims had eaten rye bread. Analysis in Marseilles revealed that the rye meal contained twenty different alkaloids. Organophosphates that might have been implicated were also found.

Ergotism is caused by mycotoxins. Claviceps purpurea contains a cocktail of different toxins: ergotamine, dihydroergotamine, ergonovine, ergocryptine, ergocristine, ergocornine, LSD (lysergic acid diethylamide) and others. They can be divided chemically into an ergotamine group, an ergoxin group and an ergotoxin group. The ergot alkaloids are derived from lysergic acid. These toxins enter the human body through everyday food, such as bread or gruel made from ergot-infected rye that has been milled into flour. The toxins cause smooth muscle contractions with vasoconstriction and uterine tetany. They also have a neurohumoral activity and produce effects on the central nervous system. In 1918, Arthur Stoll isolated ergotamine for the first time. In the period from 1938 to 1943, while conducting research into ergot, Dr Albert Hoffman accidentally discovered the hallucinogenic properties of LSD, a drug that was destined to play a major role in the hippie movement in the years following the end of the Second World War.

There are more than 35 different species within the Claviceps genus. Several of these (e.g. Claviceps paspali) contain ergot toxins. Similar toxins are present in certain plants. The seeds of the Ipomoea tricolor and Rivea corymbosa plant (Morning Glory, also known as ololiuqui; Fam. Convulvulaceae) contain the hallucinogenic LSD. It is structurally related to ergot alkaloids.

People who ingest mycotoxins with their food may develop various symptoms that are dose dependent. The symptoms may be predominantly neurological or vasospastic. There will be mental confusion with vivid hallucinations, for instance seeing brightly coloured, fierce wild animals, or visions of blood running down the walls. The afflicted person has involuntary muscular contractions, evolving into convulsions with extreme opisthotonos characterized by severe arching of the back, with the head thrown backwards, even touching the heels. This was described as St. Vitus’ dance. The victims describe a pronounced burning or itching sensation of the skin (St. Anthony’s Fire) or a tingling like insects crawling under the skin. Vasoconstriction may lead to gangrene, usually of the fingers, hands, toes, feet, ears and/or nose. In serious, non-fatal cases the symptoms may persist for up to two months.

Animals can also be poisoned. Around the roots of many plants there are mycelial threads of the so-called mycorrhizal fungi. They live together in symbiosis with the plants. Less well known are endophytes. In the case of these hidden fungi, the hyphae live inside the leaves and stalks of certain plants. Some of them protect the plant against insects and herbivores. Festuca arundinacea grass, for example, sometimes contains the endophytic ascomycete Sphacelia typhina. This fungus produces the same toxins as ergot. Cattle avoid this grass if an alternative source of feed is available. The grass species Paspalum distichum (Gramineae, knot grass) may also contain ergot alkaloids. If they do eat it, they show signs of poisoning. Cattle become lethargic. There is hypersalivation and fever, reduced milk production and prolonged gestation. They develop dry gangrene of the hooves, legs, tail and ears. Cattle and dogs display different symptoms. Dogs spin around and bite stones, sometimes until their teeth break.

Nowadays, ergotamine is used in the treatment of migraine. The reason for this lies in its ability to constrict dilated blood vessels in the cerebral membranes. Ergometrine is used after childbirth –after expulsion of the placenta– to stimulate uterine contractions and prevent postpartum haemorrhage. Hypertension is a side effect. In earlier times, sclerotia of the ergot fungus were used to induce abortion. However, its efficacy as an abortion agent is controversial because the sensitivity of the uterus is highest during the later stages of pregnancy. Bromocriptine (Parlodel®) is an ergot derivative which is used in the treatment of Parkinson’s disease and in hyperprolactinaemia. This is based on its agonistic activity on D₂-dopamine receptors. Lisuride, pergolide and metergoline are ergot derivatives with a similar activity. Methysergide is another ergot derivative that was used for the prevention of migraine. However, prolonged administration may lead to retroperitoneal fibrosis. Co-dergocrine (Hydergine®) is a mixture of dihydroergocornine, dihydroergocristine and dihydroergocryptine. At one time it had a questionable place in the treatment of dementia and peripheral vascular disorders.

In acute poisoning with a risk of gangrene, treatment consists of vasodilators, anticoagulants and low molecular weight dextrans. If necessary, a sympathetic nerve blockade may be carried out, e.g. brachial plexus blockade. Temporary sedation will be necessary in hallucination (e.g. haloperidol). Diazepam is used for convulsions. There is no specific antidote.

A flotation method can be used to separate the sclerotia from the non-infected grains of rye. The grain is immersed in a 30% KCl solution. The infected grains are lighter and float to the surface. They can then be skimmed off and destroyed. The fields should be deeply ploughed to bury the sclerotia and prevent their germinating on the surface of the soil. There are no ergot-resistant rye varieties currently available. Fungicides may be used.