Various depressing or debilitating causes, such as lowness of spirits, home-sickness, mental or bodily strain, over-eating, drinking alcohol, the action of excessive cold or heat, checking perspiration, etc., have been enumerated as causes of this disease. It is unnecessary to dwell upon such gratuitous assumptions. All of these influences are constant, but epidemic meningitis is the rarest of epidemic diseases, and the agencies referred to have no further operation than to lessen the resistance of the body to morbid influences of every description. If there be one peculiarity about this disease which is more surprising and inexplicable than another, it is that its peculiar victims are not the feeble and delicate, but the vigorous and active—not the old and decaying, but the young and stalwart.
No one of authority has claimed that this disease can be propagated by contagion. All of its early American historians are of the same opinion upon this question, and nearly all European authorities are in perfect accord with them. The apparent exceptions to this all but universal judgment are so insignificant in number and weight as not in the least to diminish its validity. A case has been published in which a pregnant woman at full term died of the disease after giving birth to an apparently healthy child. "Two hours later the infant presented symptoms of meningitis, followed rapidly by death."14 Supposing the concluding statement to be accurate, the case only shows that the cause of the disease which destroyed the mother's life infected the system of the child also. If there is one point in the history of the disease established by the concurring testimony of American and European writers, it is the extreme rarity of its attacking either the physicians and nurses in attendance upon patients affected with it, or those laboring under other diseases and occupying beds adjacent to persons ill with epidemic meningitis. That, nevertheless, there is a material morbific principle which inheres in certain localities, so that those who occupy them successively are liable to suffer from this disease, and that also this principle may be carried from place to place so as to render certain houses (barracks) infectious, seems to be demonstrated by the history of the disease in the French army. Between 1837 and 1850, when the disease prevailed in various parts of France, it did so not indiscriminately, but it usually followed the ordinary routes of communication, and especially the movements of the military in their transfers from one post to another, and the course of navigable streams. Strangely, also, it attacked soldiers much oftener than civilians. The most curious fact of all is one already referred to—viz. that although the disease prevailed in almost every part of the provinces, and although then as ever an incessant stream from them was flowing into the capital, neither its civil nor its military population was generally affected, nor, indeed, at all so, until near the close of the period mentioned. Meanwhile, however, the disease extended to several countries conterminous with France or in close and frequent intercourse with it—to Italy (1839-45), Algeria (1839-47), England, Ireland, and Denmark (1845-48). These events seem to point to a certain transmissibility of the disease until we examine the negative facts that bear upon the question. They are such as these: The epidemic did not spread at all from France into two of the adjacent countries, Belgium and Switzerland, with which the first-named country maintained an incessant intercourse by travel and traffic, but, on the other hand, it broke out at an early date within the period mentioned at places very remote and absolutely independent of all influence emanating from France or any other European source—in the south-western portions of the United States. It is by numerous facts of this description that we are compelled to remove the disease from the category of endemic and even epidemic diseases, and relegate it, along with influenza, to that of pandemic affections.
14 Med. Record, xxii. 547.
There seems to be some reason for thinking that the epidemic cause of this disease may affect the lower animals as well as man. It was stated by Gallup in 1811 that during the epidemic of meningitis in Vermont "even the foxes seemed to be affected, so that they were killed in numbers near the dwellings of the inhabitants;" and of the epidemic in 1871 in New York, Dr. Smith relates that "it was common and fatal in the large stables of the city car and stage lines, while among the people the epidemic did not properly commence until January, 1872." It would be desirable to learn more precisely the characters of these vulpine and equine epidemics before associating them with the disease we are studying, the more so that we have been unable to discover a similar relation between any epizoötic and other epidemics of meningitis. In this connection may be recalled the statement of Dr. Law of Dublin, that while he was attending a lady suffering from cerebro-spinal meningitis "nine rabbits, out of eleven which her son had, died, all in the same way: their limbs seemed to fail them, they fell on their side, and then worked in convulsions, and died." On examination of the bodies of several of them congestion of the vessels of the base of the brain was found, and also "vascularity of the membranes of the spinal marrow, indicating inflammation."15
15 Dublin Quarterly Journ., May, 1866, p. 298.
TYPES.—No disease presents a greater variety—and, indeed, dissimilarity—of symptoms than epidemic meningitis. Some of its epidemics are sthenic and even inflammatory in their type, while others have the malignant aspect of rapid blood-poisoning. These contrasts have been exhibited on a large scale, for while upon the continent of Europe the disease for the most part has presented sthenic phenomena, it has been more generally asthenic and adynamic in Ireland. One might be inclined to attribute the latter peculiarity to the permanent prevalence of typhus fever in the latter country, or rather to the special causes producing typhus, were it not that in the United States both types of the disease have been observed at different times and in different places. Such contrasts of type are, however, not unusual in other diseases that occur as epidemics, including not only the eruptive fevers, but inflammations, or affections involving inflammation, such as pneumonia, dysentery, diphtheria, etc. Hence it is evident that certain epidemics, and certain cases in each epidemic, may exhibit on the one hand a predominance of inflammatory, or on the other of adynamic or ataxic, symptoms, and each of them in every conceivable degree and combination. It is this variation of type that has led to such different conceptions of the nature of epidemic meningitis, many physicians regarding it as a fever, and many others as an inflammation, while, as we believe, it is both the one and the other, and acquires from either element, according to its ascendency, the typical character of the particular epidemic under observation.
As illustrative of these statements we may mention in this place the several forms of the disease as they have been seen and interpreted by different observers. Forget classified them as follows: (A) CEREBRO-SPINAL; 1, Explosive (foudroyante); 2, Comatose-convulsive; 3, Inflammatory; 4, Typhoid; 5, Neuralgic; 6, Hectic; 7, Paralytic. (B) CEREBRAL: 1, Cephalalgic; 2, Cephalalgic-delirious; 3, Delirious; 4, Comatose. In the first of these divisions three-sevenths belong to the first and fourth varieties. But "there were slight and severe cases; violent and hectic forms; cerebral symptoms predominant in some and spinal in others, etc."
In his excellent paper on the epidemic of 1848 in New Orleans, Ames arranged his cases in two categories—the Congestive and the Inflammatory, subdividing the former into the Malignant and the Mild. Malignant congestive cases were distinguished by prostration, coma or delirium, or both; opisthotonos; and a pulse varying extremely in its degree of frequency. In mild congestive cases a good degree of strength was preserved; the pulse was below 90; there were marked pain in the head and tenderness of the spine, but no coma, delirium, or stiffness of any muscles besides those of the neck. The purely inflammatory cases were, in general, distinguished by a temperature of the skin above that of health and a full, firm pulse, but the malignant inflammatory were marked by the early occurrence of delirium or coma, great irregularity of pulse, opisthotonos, convulsive spasm, strabismus, and occasional amaurosis, with vomiting and a rapid and fatal course; the grave, by a slighter development of the same symptoms, except coma and delirium; and the mild, by a lower grade of febrile excitement, the preservation of a good degree of strength, a tendency to become chronic, and by the absence of coma, drowsiness, delirium, and a cold stage.
Wunderlich adopted the simple plan of arranging the cases in three categories: 1, the gravest and most rapidly fatal cases; 2, the less grave; and 3, the lightest. The arrangement of Hirsch had more significance, as well as a clinical foundation—viz. 1, the abortive; 2, the explosive (m. siderans, the same as m. foudroyante of Tourdes); 3, the intermittent; 4, the typhoid.
Dr. Bedford Brown,16 who observed the epidemics in North Carolina from 1862 to 1864, arranged the cases under the following heads: 1, the inflammatory form, in which the fever is high, the pain very acute, and the delirium furious, but which is exceedingly rare; 2, the neuralgic form, which is stated to be the most frequent and protracted, with moderate fever and a pulse but slightly accelerated, and giving a favorable prognosis; 3, the ataxic form, in which great nervous depression is associated with a low and busy delirium, and the temperature "is generally much reduced below the natural standard.... This is always a dangerous form;" 4, the paralytic form, in which stupor and insensibility are early and prominent features, with a very slow and feeble pulse, blanched skin, and death by syncope.