Niemeyer,10 in common with most German and some French authors, considers cholera morbus to be a variety of gastro-intestinal catarrh. Leube11 thinks it a variety of gastric catarrh with simultaneous inflammation of the intestines and running a peculiar course. It is certainly not identical with the specific Asiatic disease, although in some cases the symptoms and morbid anatomy are exactly similar, and any differentiation is impossible. By some it is believed that cholera morbus is due to surviving germs implanted by previous epidemics of Asiatic cholera.
10 Pract. Med., 1879, vol. i. p. 480.
11 Ziemssen's Cyclopædia, New York, 1876, vol. vii. p. 146.
The slight changes found in some fatal cases would lead to the belief that the effect of the exciting cause is something more than a mechanical irritation of the gastro-intestinal mucous membrane.
The sudden onset, rapid development of symptoms, and dangerous collapse justify the theory that there must be some previous change in the individual or some peculiar result of food-decomposition. The nervous system may be so enfeebled by prolonged heat that an irritant quickly destroys its equilibrium and brings about vaso-motor paralysis of the intestinal vessels and abundant serum transudation. Or the irritation may be specific, depending upon the development of poison germs in food which has been subjected to heat influences. There is a close relationship between cholera morbus and cholera infantum in their etiology, symptoms, and pathology.
ETIOLOGY.—Predisposing Causes.—The disease is more common in the tropics, but is not confined to any climate. In temperate latitudes it is more likely to occur in July and August, when the variation of temperature between day and night is great, although the other months of summer and autumn are not entirely exempt. It is said to be more frequent and fatal in Southern Europe than in the northern and temperate climates. In periods immediately preceding and following epidemics of Asiatic cholera many persons are attacked, although there is great liability to errors in diagnosis at these times.
It occurs more frequently in youth and adolescence than in advanced life, and males seem to be more liable to attacks than females, but difference in occupation may assist in this predisposition. Persons endowed with an extreme sensibility of the nervous system and who are subject to frequent attacks of intestinal catarrh are much more liable to the disease. The exhaustion of the nervous system by heat, which is the probable explanation of the phenomena of cholera infantum, has no doubt much to do with the development of cholera morbus. Mental anxiety or overwork in summer increases this nerve-exhaustion and renders the termini of nerves and the centres very susceptible to peculiar irritation.
Exciting Causes.—It is probable that the cause of most attacks is a septic material generated in the fermentation and decomposition of food. This poison acts as an irritant upon the gastric and intestinal nerves and gives rise to excessive peristaltic movements and vomiting. Hence the quality of the food is an element of more importance in the causation than the mere quantity ingested; and herein may reside the chief difference between cholera morbus and Asiatic cholera, the latter being due to a specific, imported, or acclimated poison which invariably produces the same specific form in those exposed to its action.12 Unripe fruits, partially cooked or decaying meats and vegetables, shellfish and fish some time from the water, may produce the disease in those predisposed to it. The intemperate use of ice-water and other cold drinks after a full meal or when the body is exhausted by heat and fatigue, exposure to showers at the close of a hot day, or passing from a heated room into damp cellars and outbuildings, are frequent exciting causes.
12 "Bias the pugilist, naturally a great eater, had a sudden choleraic attack after having eaten of succulent food" (Hippocrates, lib. v. p. 247, ed. Littré).
At times there exists a certain condition of inactivity of the digestive organs when the gastric juice is not secreted in sufficient quantity, and perfectly sound food may undergo fermentation and set up an attack.