Source:  Snow, John. Med. Times and Gazette, n. s. vol. 10, May 12, 1855, pp. 457-458. [ltr. to ed., April 1855]

On the chief cause of the recent sickness and mortality in the Crimea

By John Snow, M.D.

The diseases which have been most prevalent and fatal in the Crimea have been Cholera, Dysentery, Diarrhœa, and Fever. The fever, according to what I can learn respecting it, has been typhoid, accompanied with ulceration of the small intestines, and consequently the whole of the diseases prevalent in the Crimea have consisted mainly of affections of the alimentary canal.

The communications which I made to the Medical Times and Gazette in September and October last, respecting the influence of the water-supply on the prevalence of cholera in the south districts of London, showed very clearly that this disease may be propagated by water containing the evacuations of cholera patients. The conditions were remarkably favourable for the inquiry I undertook; the circumstances and situation of a very large population were exactly the same in every particular, except that a part received a water supply containing the sewage of London, and another part, intimately mixed with it, had a water-supply quite free from such contamination. Whilst the former part of the population suffered excessively from cholera, the latter suffered no more than the population of London on the north of the Thames. The inquiries of the Registrar-General, taken up at the point at which I left off, and continued to the end of the epidemic, entirely confirmed these results.

That the water produces its effects by conveying the cholera poison, and not by its general impurity acting as an accessory or a predisposing cause, can be proved by a number of facts. In the first place the water may be very impure in time of cholera without influencing the disease, if it does not contain what comes from cholera patients. The impure water of many pump-wells and of neglected cisterns affords numerous proofs of this, and I may also mention that Dr. Glover states, as quoted by Dr. Sutherland,* that the water from the Kent Waterworks was very similar in its chemical characters to that supplied by the Southwark and Vauxhall Company, (*Report on Cholera in 1854, p. 47.) yet my inquiries and the reports of the Registrar-General show that whilst the population supplied with the latter water suffered excessively from cholera, that supplied from the Kent Waterworks suffered but very little, except in two streets at Deptford, where the water received a local contamination, which I described in the Medical Times and Gazette in September last. Now there is this great difference between the Southwark and Vauxhall water and that of the Kent Water Company–-the former is taken from the Thames, which receives the sewage of all London and the refuse of the shipping, while the latter is taken from the river Ravensbourne, which is contaminated only by the drainage of some parts of Lewisham, Eltham and Lea, where hardly any cholera existed. Another circumstance, which shows that impure water cannot be a mere predisposing cause of cholera is, that I met with several instances in the South Districts of London, in which persons were attacked by this disease within eight and forty hours after arriving from parts of the country not affected with cholera; these persons drank the water of the Southwark and Vauxhall Company after their arrival. Lastly, the fact of a number of persons being attacked at one time, after one or two cases of cholera have occurred amongst those whose evacuations habitually contaminate the ditch or pump-well from which they drink, shows that the water contains the real and efficient cause of the malady; for if the excess of cases was merely occasioned by the ordinary impurity of the water always present, it would be distributed over the whole time of the epidemic, instead of occurring in one sudden and intense outbreak.

The proof of the communication of cholera through the medium of water, of course completely confirms the fact of its propagation in a more direct way, by swallowing the morbid poison without the water, in the crowded dwellings of the poor, in coal pits, and other situations.

The proof of the manner of communication of the other diseases which have been prevalent in the Crimea is not so conclusive as that which regards cholera, but the evidence which can be collected on the subject tends to show that they are propagated in the same way as cholera. Dysentery has often been noticed to be occasioned, or kept up, by the use of water containing human excrement. This was observed by Mr. Bell, of Cork, in the old barracks at that town.* (*Dr. Cheyne on Dysentery, Dublin Hospital Reports. Vol III.) The prevalence of dysentery among the crews of ships stationed in the great rivers of India and China has been noticed by nearly all writers on the diseases which prevail in tropical climates, and Dr. Bryson has related a number of instances in which both dysentery and fever seemed to be occasioned by drinking the water of the Yang-tse-Kiang, the Canton river, and other rivers of China.† (†Statistical Reports on the Health of the Navy. Part II. 1853.) Along with other impurities the great rivers of India and China contain the fæces of a large population, amongst whom dysentery always prevails more or less. One circumstance worthy of remark is, that Dr. Bryson and several other writers have alluded to the great frequency of intestinal worms, chiefly lumbrici, in the cases of dysentery and fever in the above situations. I do not, of course, consider there is any connexion between the other diseases and the worms, but the existence of these creatures proves that the patients have been exposed to swallow matters which have come from the bowels of other persons; as the worms can only arise from the ova of their own species, produced by the animal in its proper habitat. In the Medical Times of March 31, p. 318, Mr. Prentice relates how he contracted dysentery by drinking the water of a pool in the half-formed course of a stream in Australia. That colony was once, like California and many new countries, famous for the healthiness of the new settlers, which was erroneously attributed to the climate. Its reputation for health has been gradually dispelled as one fresh disease after another has been imported, and the diggings are infested with some of the bowel complaints which infest camps and other places where persons reside together in great numbers, without the appliances for drainage and water-supply which usually exist in a town.

The production of diarrhœa by water containing sewage matters is well known. I have been informed by many persons that they were attacked with diarrhœa on first going to live in some of the southern suburbs of London, and drinking the impure water of the Thames, supplied to them by the Southwark and Vauxhall Company. Sailors often suffer in the same way, from drinking the Thames water before it has spontaneously purified itself; and I was lately informed by a Medical man, who has lived in St. Petersburg, that strangers are nearly always attacked with diarrhœa and colic on first drinking the water of the Neva, which receives the sewage of the town. In the autumn of 1853 diarrhœa was very prevalent in Croydon, and Mr. Carpenter, Surgeon, of that town, found that it was caused by the impure water of the pump-wells. Nine-tenths of the people of Croydon were drinking the new water supplied by the Board of Health; but, out of thirty-two patients with diarrhœa who came under the care of Mr. Carpenter, twenty-five were drinking well-water entirely; five drank water from both sources, and the other two could not say decidedly that they had not drunk well-water.‡ (‡Association Journal, Oct 6, 1854.)

Mr. Carpenter has also traced the great epidemic of typhoid fever which prevailed in Croydon in the previous year, to contamination of the water of the pump wells, occasioned by [457/458] the disturbance of the ground and of many old cesspools in the new drainage operations which preceded that outbreak.* (*Loc, cit.) The stoppage of many of the porcelain pipes, and the consequent leakage from them into the ground soon after they were laid down, must have greatly assisted in the propagation of the disease through the pump water. Dr. Flint of America relates an instance occurring at North Boston, Erie County, New York, in which typhoid fever was apparently communicated to a number of families by the contamination of the water of a pump-well which they were using,† and Ihave been informed of some other instances of the same kind. (†Clinical Reports of Continued Fevers. Buffalo. 1852.)

The diseases which have prevailed among the troops in the Crimea were all present, with the exception of scurvy, before they left Varna, as soldiers ill of cholera, dysentery, and diarrhœa were sent from the latter place to the Bosphorus at the time the expedition sailed to the Crimea. The French when at Varna suffered from cholera much more then the English, but after the allied armies removed to the Crimea the sickness and mortality from cholera and other diseases was much greater amongst the British troops than the French. The chief cause of this circumstance probably is that the French, soon after sitting down before Sebastopol, laid down iron pipes to convey water to the army from the hills above the camp, whilst the English adopted no such measure.

I find from a leading article in the Medical Times and Gazette of March 10, that "the water which many of them (the soldiers) drank was impregnated with the most disgusting filth, for it seems that almost the only water used for drinking in the vicinity of Balaklava is that of a small stream which flows from the adjacent mountains, and in its whole course receives the remains of dead horses, the offal of the slaughtered oxen, and even sometimes bodies of dead men." This stream must also have received the excrement of the troops, for any measures which would have defended it from this latter kind of pollution would also have saved it from those which are mentioned above.

There are some springs which supply water to part of the British army before Sebastopol. The ground, however, consists of limestone and clay, neither of which has the property which is possessed by sandstone and gravel of oxidizing and destroying organic matter. It is extremely probable, therefore, that the springs are also contaminated with the excreta of the troops. A proper examination of the situation of the springs and of the nature of the water might help to decide this, for though neither chemistry nor the microscope can do anything towards detecting morbid poisons, they may be used to determine whether or not the animal matters which percolate the soil are entirely changed into nitrates and other mineral substances before they reach the water.

The distribution of rum to the army has probably been a great cause of the propagation of disease through the medium of polluted water. Malt liquors do not require to be diluted, and tea, coffee, and cocoa are always prepared with boiled water; whilst on the other hand distilled spirits require to be diluted with water, which generally is not boiled.

It is quite obvious that every disease which can be communicated through the medium of water may also be communicated by swallowing the morbid matter without the water. It is, therefore, probable that the want of water for washing the hands must have assisted in the propagation of the various maladies amongst the soldiers, several of whom live together in a small tent. This is most likely one of the reasons why the common soldiers have suffered a greater mortality from disease than the officers; another reason probably is that the officers would be more particular about the water they drank; I have been informed of some who sent their servants a great distance for it, as early as four o’clock in the morning, before the horses should come to drink and render the stream muddy. As the officers suffered less from fatigue and exposure to the weather than the soldiers, they would also be in a better condition to recover from any disease with which they might be attacked.

Since all the chief diseases which have been so fatal in the Crimea were present in the army before it left Varna, we do not require to look for their causes in the former place, but only for the means of their propagation, which appear to have been abundant enough, as I have endeavoured to show above. The overwork, the exposure to cold, and the occasional privation which the men have suffered would lessen chances of recovery from the diseases with which they were attacked. These circumstances could not produce a case of specific disease, like cholera or fever; it is very doubtful whether they could produce dysentery, and the only one out of the four chief diseases which have prevailed in the Crimea that might be caused by any of the above circumstances is diarrhœa. The indigestible food sometimes served out, and the extreme exposure to the weather might cause this latter complaint, but that extreme labour, cold, and privation do not of themselves occasion epidemic diseases is shown in the history of the expeditions to the Arctic regions, where the adventurers die only from accident or absolute starvation.

At a time when the chemistry of gaseous substances did not exist, and when certain fevers, dysentery, and some other diseases were attributed to a putrefaction of the fluids of the living body, these diseases were supposed to be occasioned by the effluvia given off during ordinary putrefaction. These opinions have still a certain number of adherents, even in official quarters, and it is worthy of the attention of those individuals that the greatest mortality in the Crimea took place at a time when the temperature was too low for putrefaction to go on, and when it was especially noticed that though many dead horses were lying about they emitted no smell.

The chief means of preserving the health of troops in a camp is to have water conveyed in pipes or otherwise from some place where it is out of the reach of contamination, and until such a measure can be taken no water should be drunk that has not first been boiled. As regards the drainage at a camp, it should be borne in mind that it is chiefly useful in preventing the pollution of the water. When this rule is not considered, drainage may become a source of the propagation of disease, as recently at Croydon, Sandgate, and other places, instead of being its prevention. The advice of Sir John Pringle that the men should be compelled to make use of the camp privies on all occasions ought to be attended to, and the privies should be so constructed and kept that the hands would not be liable to get soiled by them.

Sir John Pringle insisted more than a hundred years ago on the advantage of having a number of small hospitals instead of one of greater extent, in order to check as much as possible the spread of disease by contagion. Our Allies have acted on this advice in preparing a number of small hospitals along the shores of the Bosphorus; but the authorities of Sir John Pringle’s own country have totally disregarded it in forming an hospital of gigantic dimensions at Scutari, with a result that is too well known to require comment. Official persons in this country have generally acted of late years as if there were no such thing as the communication of disease; but the great mortality amongst Medical men and nurses at Scutari ought to convince them of their error.

18, Sackville-street, April, 1855.

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