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"On the pathology and mode of communication of cholera"

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(13 October 1849)

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"Westminster Medical Society," Lancet 2 (20 October 1849): 431-33.

[The minutes include Snow's remarks, plus some discussion (including remarks of Dr. Swayne from Bristol, one of the proponents of the cholera-fungus theory) before the debate was adjourned until the next meeting of the Society.]

Megan Anderson and Cori Heacock made the following transcription.

Westminster Medical Society.

Saturday, October 13, 1849.

Mr. Hird, President.

The interest regarding the discussion on cholera continues unabated. The rooms of the Society, this evening, were crowded to excess. Dr. Swayne, of Bristol, was among the visitors. Seventeen new fellows were elected; and a great number of new ones proposed. The discussion on Dr. Webster's paper was postponed, by consent, until Dr. Snow had read his paper

"On the pathology and mode of communication of cholera."

He said that he had been led, contrary to the usual opinion, to consider cholera as being, in the first instance at least, a local affection of the mucous membrane of the alimentary canal, and not an affection of the whole system, depending on a poison in the blood. In diseases caused by a special poison absorbed into the blood, general illness of a febrile character preceded any local symptoms which might arise; but this was not the case in cholera. The loss of the watery part of the blood, in all the cases he had seen, was sufficient to account for the collapse and all the general symptoms; and when cholera commenced gradually, it could often be checked, and prevented from proceeding beyond the stage of diarrhœa, by remedies adapted to act merely on the mucous membrane. The recent discovery of peculiar microscopic cells, believed to be of a vegetable character, in great abundance, in the cholera discharges, tended to confirm this view of the nature of cholera. An attentive examination of the history of cholera, as an epidemic, showed that it was communicable by human intercourse; and although there were many facts opposed to the theory of cholera being contagious, in the same way that the eruptive fevers were believed to be, yet, in the sequel, these facts would afford the strongest evidence of the communication of the disease. If the alimentary canal were the seat of cholera, and the disease were communicable, it was clear that it must be conveyed by something which passed from the mucous membrane of the stomach and intestines of one patient to that of another, which it could only do by being swallowed; and as the disease grows in a community by what it feeds upon, attacking a few people in a town first, and then becoming more prevalent, the cholera poison must multiply itself by a kind of growth, like every other morbid poison. The instances in which minute quantities of the ejections and dejections of cholera patients must be swallowed were sufficiently numerous to account for the spread of the disease; and it spread most where the facilities of this mode of communication were greatest. [431/432]

The bed-linen nearly always became wetted by the cholera evacuations, which were almost without colour and odour; and the hands of persons waiting on the patient became soiled without their noticing it; consequently, unless they were very cleanly in their habits, and also had opportunity for washing their hands, they would be liable to swallow some of the excretion, and leave portions on the food they handled or prepared, which had to be eaten by the rest of the family, who, amongst the working classes, had to eat their meals generally in the sick room; hence the thousands of instances in which, in this class of the population, a case of cholera in one member of the family was followed by other cases; whilst medical men and others who merely visited the patient, without taking food, generally escaped. The mining population of this country had suffered more from cholera than any other; there were no privies in the mines, and as the workmen usually stayed down for eight hours at a time, they took food with them, which they ate with unwashed hands; hence, in the event of one workman getting the cholera, the others were very liable to contract the disease, and take it to their families. One important medium of the conveyance of the cholera poison from one patient to another was the drinking-water, when it became contaminated by the evacuations, either by their permeating the ground and getting into wells, or by their being conveyed by sewers into a river. Since he (Dr. Snow) first published his views on this point, Dr. William Budd had found the microscopic bodies before alluded to in such drinking-water of cholera districts as received the contents of sewers. Dr. Snow then related a number of instances where, as in Albion-terrace, Wandsworth-road, there was a very high mortality from cholera in connexion with the contamination of the water with discharges from the patients. He attributed the high mortality on the south side of the Thames to three causes--viz., the drinking from certain tidal ditches, which prevails to so great extent in Rotherhithe and Bermondsey; the water supplied by the water-works in this part of London, which is generally procured from the Thames in the midst of sewers; and to the contamination of a number of the wells by the contents of the cesspools, which are often as deep as the wells. The low elevation of the ground had no connexion with cholera, except when combined with infected water. Westminster had the same elevation as the Borough, and yet the mortality from cholera was not half so great. Bethlem Hospital and the Queen's Prison had all but escaped cholera, situated in a low level, but having pure water of their own. The Brixton district was chiefly on elevated ground, and yet the mortality there had been high, as a great part of the district was supplied with water got out of the Thames near the Hungerford Suspension Bridge, by the Lambeth Waterworks. In Exeter, in 1832, the greater part of the people were supplied with water, into which, as he had learnt from Dr. Shapter, one of the chief sewers emptied itself. This sewer brought the sewage from the street in which two of the first cases of cholera introduced from Plymouth occurred; the disease was in a few days scattered through the town, and was very fatal. Since that time, Exeter had been copiously supplied with water quite free from the sewage of the town, and this year there have been but a few cases of cholera, and those chiefly of strangers just arrived from places in which it was prevailing. Hull had also got a new and more plentiful supply of water since 1832, at which time it was scantily supplied with water conveyed from some springs. The new supply was from the river Hull, which received half the sewage of the town, and which is washed up by the tide past the waterworks, as he had learnt from Dr. Horner. In 1832, cholera in Hull was confined to the poor, of whom it carried off 300; this year it had assailed all classes, and about six times that number had died, although eight or ten thousand people had left the town to escape from the disease. Certain towns, as Birmingham, Bath, Cheltenham, and Leicester, had almost escaped cholera both in 1832 and the present year. These towns were supplied with water quite uncontaminated by the sewers. He gave some recommendations for the prevention of cholera, the chief of which were, extreme cleanliness in those waiting on the sick, and the avoidance of tainted water, or at least having it well boiled before it was used. Dr. Brittan had found microscopic bodies in the atmosphere, which he considered to be the same as those existing in the alimentary canal. He (Dr. Snow) understood that others had not succeeded in finding them in the air, and he was of opinion, that if they should be generally found in the atmosphere, even of infected districts, they could not be the real causes of cholera, for all the evidence he had collected was opposed to the idea that the cause of cholera existed in the air.

Dr. Swayne said, that he felt quite disposed to agree with the remarks which had been made by Dr. Snow in his paper respecting the probability of cholera being primarily a disease of the alimentary canal and not of the blood. The rapidity with which the disease, when in a incipient stage, may be arrested by appropriate treatment, would seem to show this; and the fact also, that certain cells of a very peculiar character had been detected, whilst undergoing their various stages of development, in the alimentary canal, would appear to strengthen such a belief. These bodies, which he would now describe, were first observed by Dr. Brittan and himself whilst engaged as members of a sub-committee of the Bristol Medico-Chirurgical Society, in a microscopical investigation of the evacuations of cholera. During the course of this investigation they had examined specimens from nearly sixty patients, and had failed to detect the bodies in question in only five or six cases. These, it is true, were unusually severe, but this did not, he thought, invalidate their conclusions, for in such cases it had been possible to obtain only one evacuation before death; and it had happened in other cases, where these bodies had been found in abundance in subsequent evacuations, that they were wanting in the first motion. The peculiar bodies alluded to were usually found in the matters rejected from the stomach and first portions of the alimentary canal to be very small, and in an early stage of development, and much resembling those which had been subsequently detected by Dr. Brittan in the atmosphere. In the discharges from the lower portions of the intestinal tube they were much larger and more fully developed, although occasionally the smaller cells were also met with in considerable abundance. Most of the larger cells thus observed were broken and fissured in certain parts of their circumference, and flattened, as if either from rupture or exosmosis of their fluid contents; so that it was uncommon to meet with such cells in a perfect condition. Dr. Swayne said, however, that he had lately had an opportunity of observing cells of this kind in a very perfect state, and of tracing in the same specimen the gradations from this to the imperfect form; and he referred to a diagram he had made, which exhibited their peculiar structure. Their walls appeared to be thick, and studded externally with buds, some of which could be seen to be partially, and others to be completely detached from the parent cell. The cells contained within them a mass of granular matter, which did not always completely fill its cavity, but sometimes left a space around it, which appeared to be occupied by a transparent fluid. When crushed by pressure, these cells gave exit to a number of granules and very minute cells, resembling the smallest-sized cells detected in the atmosphere. Dr. Swayne then made some remarks with respect to the mode of propagation of cholera, and alluded to a circumstance which had been noticed to him by one of the district surgeons in Bristol, and which his own experience had confirmed- viz., the frequency with which the disease attacked washerwomen and others who had had much to do with the discharges of cholera patients. Dr. Carpenter had also mentioned to him that he had been informed by an American friend that this was particularly noticed at Philadelphia, when the proportion of washerwomen among the cholera patients was such as strongly to attract attention. Dr. Swayne then related a circumstance which occurred to himself- viz., that he was attacked one day with headach and nausea whilst in the act of emptying several bottles of cholera evacuations which he had been examining. This was followed by fever and restlessness during the night, and the ensuing morning by violent diarrhea. Dr. Swayne also alluded to the large quantities of crystalline and amorphous matters usually found in the urine, which are present in the evacuations of cholera, and stated that he had examined the dejections in several well-marked cases of diarrhea from other causes, without detecting the peculiar cellular bodies which he had described.

Dr. O. Ward remarked that among several young ladies' schools which he attended, neither diarrhea nor cholera had occurred. This made him think that diarrhea was the common disease, and cholera only the exception. He mentioned that he had noticed that in places where there was much stagnant water, and where small-pox and scarlet fever had been prevalent, the cholera had been rife. Parts, also, which in 1832 had been much infected with cholera, had, during the late epidemic, escaped, owing to better drainage and improvement in the supply of water. He stated, with respect to miners, that the wells in the neighborhood of miners were dried up, and that the work-people obtained their water from the mine itself, the water from which, being pumped up from the pit, ran down into reservoirs, and was thence obtained for use. This might explain the cause of [432/433] cholera being so prevalent in mining districts. Birmingham and Leicester were so hilly that the drainage was good; hence their immunity from the disease.

Mr. Walshe explained why, in districts where the water in open tidal ditches was too offensive to use in any way, cholera was less prevalent than where that fluid was somewhat more pure; for in one the people refrained from drinking it, while in the other, as about "Jacob's Island," in Rotherhithe, it was no uncommon thing to see people making use of the necessaries over the stream from which they fetched their supply of water. He spoke of the value of house-to-house visitation as likely to forma supply of valuable materials respecting the cause of the disease and its mode of propagation.

Dr. Willshire could not agree with Drs. Swayne and Snow that the cholera was at first a merely local disease, and that it was occasionally arrested by the use of chalk mixture &C. Often did we see cholera patients in a state of collapse, and half dead before the "local" affection of the alimentary canal presented itself; the remedies in question were then of no use whatever; was it to be said, that those cases of diarrhea which chalk mixture &c. cure were really cases of cholera? Did not, on the contrary, the treatment usually found most successful in cholera- the saline treatment of Stevens- militate against the opinion of the local nature of the disease? He did not regard the condition of the water in certain localities as the cause of cholera; if it were, why had we been free from the disease since 1832, since which time the cause in question had existed. The water bore a mere contingent relation to the disease, nothing more.

Dr. Copeland said that he considered cholera to be an affection of the whole system, but directing its chief virulence on the alimentary canal. He was greatly interested in the discovery of the microscopic bodies. He had long been of opinion that the decomposing effluvia given off in infectious diseases might take on special organized forms peculiar to each disease, and had recommended this subject to the notice of histologists some years ago.

Dr. Stewart alluded to an experiment performed by some French physicians, at Warsaw, in 1831, of swallowing some portion of the cholera stools, and said, that as that was followed by no ill effects, it was opposed to the opinion of Dr. Snow. He considered, also, that Dr. Snow's hypotheses did not explain certain great and sudden outbreaks of cholera that had happened in India.

The debate was adjourned until Saturday, October 20th.

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