In close relation to the cases of infection with animal or plant parasites which have been discussed, there are certain well-established instances of poisoning by substances that have been generated in food while it is still outside of the body. This is the common type of food poisoning in popular estimation, but in point of fact the proved cases of this class are much less frequent than the instances of true infection with bacteria of the paratyphoid-enteritidis group ([chapter vi]). Thus far the best-known examples of poisoning by the products of micro-organisms are botulism and ergotism.
ERGOTISM
Ergotism or ergot poisoning is due to the use of rye that has become diseased through the attack of a fungus, Claviceps purpurea. It occurred frequently in the Middle Ages when in times of famine the ergot or spurred rye (O.Fr. argot, "a cock's spur") was often used in default of better food. In Limoges in 922 it is said that forty thousand persons perished from this cause. Improvement in the facilities for transportation of food into regions where crops have failed, and the use of special methods for separating the diseased grain from the wholesome have greatly reduced the prevalence of ergotism. In Western Europe poisoning from this cause has practically ceased, although Hirsch recorded some twenty-eight outbreaks in the nineteenth century; in parts of Russia the disease is said still to occur in years of bad harvest.[95]
The poison ergot itself has long been used as a drug in obstetrics, but its composition is complex and is still not completely understood. Several constituents of ergot have been extracted, and these have been shown to possess different physiological effects.[96] The symptoms observed in the outbreaks of ergotism of mediaeval times are not wholly reproduced experimentally by the drug and are thought to have been in part due to the semi-starvation engendered by the use of rye from which the nutritious portions had been largely removed by the growth of the fungus.
BOTULISM
The best established case of poisoning by means of bacterial products taken in with the food is the serious malady known somewhat inappropriately as botulism (botulus, sausage).[97] This kind of food poisoning, which has a characteristic set of symptoms, seems to have been first recognized and described in 1820 by the German poet and medical writer Justinus Kerner. In two articles (1820-22) he enumerates 174 cases with 71 deaths occurring in Württemberg between 1793 and 1822 and apparently in most cases connected with the use of insufficiently smoked sausage. Mayer[98] tabulates about 600 additional cases observed in various parts of Germany down to the end of 1908, the total mortality in the 800 cases being about 25 per cent. In France botulism is said to be very rare.[99] In Great Britain Savage[100] declares that he has been unable to trace the occurrence of a single outbreak. In the United States several instances of botulism poisoning are on record (Sheppard,[101] 1907, 3 cases, 3 deaths, canned pork and beans; Peck,[102] 1910, 12 cases, 11 deaths; Wilbur and Ophüls,[103] 1914, canned string beans, 12 cases, 1 death; Frost,[104] 1915, 3 cases, 3 deaths). Professor Stiles[105] has given a graphic description of his own attack of probable botulism due in all likelihood to minced chicken.
Fig. 10.—Claviceps purpurea: 1, ergot on rye-grass; 2, ergot on rye; 3, section of a portion of the conidial form of fruit, ×300; 4, a sclerotium or ergot; 5, head of ascigerous form of fruit; 6, an ascus, ×300; 7, a single spore, ×300. (After Massee, Plant Diseases, by courtesy of the Macmillan Company.)
Symptoms.—The description of a case seen by Wilbur and Ophüls,[106] is so typical that it may be cited: