From case histories it is known that the toxin is stable as four-month-old pickled quail have been poisonous. Humans vary in their susceptibility; only one in four people who consumed quail soup containing the toxin fell ill. The toxin is apparently fat-soluble as potatoes fried in quail fat have proved poisonous. Coniine from hemlock consumed by quail has been suggested as the cause, though quail resist eating hemlock. Hellebore has also been suggested as the source of the toxin. It has also been asserted that this evidence points to the seeds of the annual woundwort being the causal agent. It has been suggested that Galeopsis ladanum seeds are not responsible.
Epidemiology
Migration routes and season may affect quail risk. Quail are never poisonous outside the migration season nor are the vast majority poisonous while migrating. European common quail migrate along three different flyways each with different poisoning characteristics, at least in 20th century records. The western flyway across Algeria to France is associated with poisonings only on the spring migration and not on the autumn return. The eastern flyway, which funnels down the Nile Valley is the reverse. Poisonings were only reported in the autumn migration before the quail had crossed the Mediterranean. The central flyway across Italy had no associated poisonings. Migrating quail used to be caught and eaten in prodigious numbers but modern farming and droughts in the Sahel have led to a vast reduction in the size of the migrations. Conservation efforts and the availability of farmed quail have also reduced the consumption of these wild birds. Coturnism may well disappear before it is understood.
History
The condition was certainly known by the 4th century BC to ancient Greek, and subsequently Roman, naturalists, physicians and theologians. The Bible mentions an incident where the Israelites became ill after having consumed large amounts of quail in Sinai. Philo gives a more detailed version of the same Biblical story. Early writers used quail as the standard example of an animal that could eat something poisonous to man without ill effects for themselves. Aristotle, Philo, Lucretius, Galen and Sextus Empiricus all make this point. Central to these ancient accounts is the thesis that quail became toxic to humans after consuming seeds from hellebore or henbane. However Sextus Empiricus suggested that quail ate hemlock, an idea revived in the 20th century. Confirmation that the ancients understood the problem, comes from a 10th-century text Geoponica, based on ancient sources. This states, "Quails may graze hellebore putting those who afterwards eat them at risk of convulsions and vertigo....".
