Infectious and Epidemic Disease in History

Department of History
University of California, Irvine
 Instructor:    Dr. Barbara J. Becker

Week 8.  Contact?

excerpts from
On the Mode of Communication of Cholera (1855)
by John Snow, M.D. (1813-1858)

History of Cholera
The existence of Asiatic Cholera cannot be distinctly traced back further than the year 1769.  Previous to that time the greater part of India was unknown to European medical men; and this is probably the reason why the history of cholera does not extend to a more remote period.  It has been proved by various documents ... that cholera was prevalent at Madras in the year above mentioned, and that it carried off many thousands of persons in the peninsula of India from that time to 1790.  From this period we have very little account of the disease till 1814, although, of course, it might exist in many parts of Asia without coming under the notice of Europeans.

In June 1814, the cholera appeared with great severity in the first battalion, ninth regiment, N.I., on its march from Jaulnah to Trichinopoly; while another battalion, which accompanied it, did not suffer, although it had been exposed to exactly the same circumstances, with one exception....

In 1817, the cholera prevailed with unusual virulence at several places in the Delta of the Ganges; and, as it had not been previously seen by the medical men practicing in that part of India, it was thought by them to be a new disease.  At this time the cholera began to spread to an extent not before known; and, in the course of seven years, it reached, eastward, to China and the Philippine Islands; southward, to the Mauritius and Bourbon; and to the northwest, as far as Persia and Turkey.  Its approach towards our own country, after it entered Europe, was watched with more intense anxiety than its progress in other directions....

There are certain circumstances ... connected with the progress of cholera, which may be stated in a general way.  It travels along the great tracks of human intercourse, never going faster than people travel, and generally much more slowly.  In extending to a fresh island or continent, it always appears first at a seaport.  It never attacks the crews of ships going from a country free from cholera, to one where the disease is prevailing, till they have entered a port, or had intercourse with the shore.  Its exact progress from town to town cannot always be traced; but it has never appeared except where there has been ample opportunity for it to be conveyed by human intercourse.

There are also innumerable instances which prove the communication of cholera, by individual cases of the disease, in the most convincing manner....

Cases Proving Person to Person Transmission
The first case of decided Asiatic cholera in London, in the autumn of 1848, was that of a seaman named John Harnold, who had newly arrived by the Elbe steamer from Hamburgh, where the disease was prevailing.  He left the vessel, and went to live at No. 8, New Lane, Gainsford Street, Horsleydown.  He was seized with cholera on the 22nd of September, and died in a few hours....

Now the next case of cholera, in London, occurred in the very room in which the above patient died.  A man named Blenkinsopp came to lodge in the same room.  He was attacked with cholera on the 30th September....

[Snow then cites several attending physicians' reports on the cholera victims they have personally observed and treated.]

It would be easy, by going through the medical journals and works which have been published on cholera, to quote as many cases similar to the above as would fill a large volume.  But the above instances are quite sufficient to show that cholera can be communicated from the sick to the healthy; for it is quite impossible that even a tenth part of these cases of consecutive illness could have followed each other by mere coincidence, without being connected as cause and effect.

Not Communicated by Means of Effluvia
It used to be generally assumed, that if cholera were a catching or communicable disease, it must spread by effluvia given off from the patient into the surrounding air, and inhaled by others into the lungs.  This assumption led to very conflicting opinions respecting the disease.  A little reflection shows, however, that we have no right thus to limit the way in which a disease may be propagated, for the communicable diseases of which we have a correct knowledge spread in very different manners.  The itch, and certain other diseases of the skin, are propagated in one way; syphilis, in another way; and intestinal worms in a third way, quite distinct from either of the others.

Pathology Indicates Manner of Communication
A consideration of the pathology of cholera is capable of indicating to us the manner in which the disease is communicated.  If it were ushered in by fever, or any other general constitutional disorder, then we should be furnished with no clue to the way in which the morbid poison enters the system; whether, for instance, by the alimentary canal, by the lungs, or in some other manner, but should be left to determine this point by circumstances unconnected with the pathology of the disease.  But from all that I have been able to learn of cholera, both from my own observations and the descriptions of others, I conclude that cholera invariably commences with the affection of the alimentary canal.

The disease often proceeds with so little feeling of general illness, that the patient does not consider himself in danger, or even apply for advice, till the malady is far advanced.  In a few cases, indeed, there are dizziness, faintness, and a feeling of sinking, before discharges from the stomach or bowels actually take place; but there can be no doubt that these symptoms depend on the exudation from the mucous membrane, which is soon afterwards copiously evacuated....  In all the cases of cholera that I have attended, the loss of fluid from the stomach and bowels has been sufficient to account for the collapse, when the previous condition of the patient was taken into account, together with the suddenness of the loss, and the circumstance that the process of absorption appears to be suspended....

Propagated by Morbid Poison Entering the Alimentary Canal
Diseases which are communicated from person to person are caused by some material which passes from the sick to the healthy, and which has the property of increasing and multiplying in the systems of the persons it attacks.  In syphilis, smallpox, and vaccinia, we have physical proof of the increase of the morbid material, and in other communicable diseases the evidence of this increase, derived from the fact of their extension, is equally conclusive.

As cholera commences with an affection of the alimentary canal, and ... the blood is not under the influence of any poison in the early stages of this disease, it follows that the morbid material producing cholera must be introduced into the alimentary canal must, in fact, be swallowed accidentally, for persons would not take it intentionally; and the increase of the morbid material, or cholera poison, must take place in the interior of the stomach and bowels.

It would seem that the cholera poison, when reproduced in sufficient quantity, acts as an irritant on the surface of the stomach and intestines, or, what is still more probable, it withdraws fluid from the blood circulating in the capillaries, by a power analogous to that by which the epithelial cells of the various organs abstract the different secretions in the healthy body.  For the morbid matter of cholera having the property of reproducing its own kind, must necessarily have some sort of structure, most likely that of a cell.  It is no objection to this view that the structure of the cholera poison cannot be recognized by the microscope, for the matter of smallpox and of chancre can only be recognized by their effects, and not by their physical properties.

The period which intervenes between the time when a morbid poison enters the system, and the commencement of the illness which follows, is called the period of incubation.  It is, in reality, a period of reproduction, as regards the morbid matter; and the disease is due to the crop or progeny resulting from the small quantity of poison first introduced.  In cholera, this period of incubation or reproduction is much shorter than in most other epidemic or communicable diseases.  From the cases previously detailed, it is shown to be in general only from twenty-four to forty-eight hours.  It is owing to this shortness of the period of incubation, and to the quantity of the morbid poison thrown off in the evacuations, that cholera sometimes spreads with a rapidity unknown in other diseases....

The instances in which minute quantities of the ejections and defections of cholera patients must be swallowed are sufficiently numerous to account for the spread of the disease; and on examination it is found to spread most where the facilities for this mode of communication are greatest.

Nothing has been found to favour the extension of cholera more than want of personal cleanliness, whether arising from habit or scarcity of water, although the circumstance till lately remained unexplained.  The bed linen nearly always becomes wetted by the cholera evacuations, and as these are devoid of the usual colour and odour, the hands of persons waiting on the patient become soiled without their knowing it; and unless these persons are scrupulously cleanly in their habits, and wash their hands before taking food, they must accidentally swallow some of the excretion, and leave some on the food they handle or prepare, which has to be eaten by the rest of the family, who, amongst the working classes, often have to take their meals in the sick room:  hence the thousands of instances in which, amongst this class of the population, a case of cholera in one member of the family is followed by other cases; whilst medical men and others, who merely visit the patients, generally escape....


[Snow relates several instances of the communication of cholera through the medium of polluted water.]

Instances of the Communication of Cholera through the Medium of Polluted Water in the Neighborhood of Broad Street, Golden Square [1 on the map below]
The most terrible outbreak of cholera which ever occurred in this kingdom, is probably that which took place in Broad Street, Golden Square, and the adjoining streets, a few weeks ago.  Within two hundred and fifty yards of the spot where Cambridge Street joins Broad Street [2 on the map below], there were upwards of five hundred fatal attacks of cholera in ten days.  The mortality in this limited area probably equals any that was ever caused in this country, even by the plague; and it was much more sudden, as the greater number of cases terminated in a few hours.

The mortality would undoubtedly have been much greater had it not been for the flight of the population.  Persons in furnished lodgings left first, then other lodgers went away, leaving their furniture to be sent for when they could meet with a place to put it in.  Many houses were closed altogether, owing to the death of the proprietors; and, in a great number of instances, the tradesmen who remained had sent away their families: so that in less than six days from the commencement of the outbreak, the most afflicted streets were deserted by more than three-quarters of their inhabitants....

As soon as I became acquainted with the situation and extent of this irruption of cholera, I suspected some contamination of the water of the much-frequented street-pump in Broad Street, near the end of Cambridge Street [2 on the map below]; but on examining the water, on the evening of the 3rd September, I found so little impurity in it of an organic nature, that I hesitated to come to a conclusion.

Further inquiry, however, showed me that there was no other circumstance or agent common to the circumscribed locality in which this sudden increase of cholera occurred, and not extending beyond it, except the water of the above mentioned pump....

On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the pump.  There were only ten deaths in houses situated decidedly nearer to another street pump.  In five of these cases the families of the deceased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pump which was nearer.  In three other cases, the deceased were children who went to school near the pump in Broad Street.  Two of them were known to drink the water; and the parents of the third think it probable that it did so.  The other two deaths, beyond the district which this pump supplies, represent only the amount of mortality from cholera that was occurring before the irruption took place.

With regard to the deaths occurring in the locality belonging to the pump, there were sixty-one instances in which I was informed that the deceased persons used to drink the pump-water from Broad Street, either constantly, or occasionally.  In six instances I could get no information, owing to the death or departure of every one connected with the deceased individuals; and in six cases I was informed that the deceased persons did not drink the pump-water before their illness.

The result of the inquiry then was, that there had been no particular outbreak or increase of cholera, in this part of London, except among the persons who were in the habit of drinking the water of the above-mentioned pump-well.

I had an interview with the Board of Guardians of St. James's parish, on the evening of Thursday, 7th September, and represented the above circumstances to them.  In consequence of what I said, the handle of the pump was removed on the following day....

There are certain circumstances bearing on the subject of this outbreak of cholera which require to be mentioned.  The Workhouse [3 on the map below] in Poland Street is more than three-fourths surrounded by houses in which deaths from cholera occurred, yet out of five hundred and thirty-five inmates only five died of cholera, the other deaths which took place being those of persons admitted after they were attacked.  The workhouse has a pump-well on the premises, in addition to the supply from the Grand Junction Water Works, and the inmates never sent to Broad Street for water....

There is a Brewery [4 on the map below] in Broad Street, near to the pump, and on perceiving that no brewer's men were registered as having died of cholera, I called on Mr. Huggins, the proprietor.... The men are allowed a certain quantity of malt liquor, and Mr. Huggins believes they do not drink water at all; and he is quite certain that the workmen never obtained water from the pump in the street....

At the percussion-cap manufactory, [38] Broad Street, [5 on the map below] where ... about two hundred workpeople were employed, two tubs were kept on the premises always supplied with water from the pump in the street, for those to drink who wished; and eighteen of these workpeople died of cholera at their own homes....

In the "Weekly Return of Births and Deaths" of September 9th, the following death is recorded as occurring in the Hampstead district:  "At West End, on 2nd September, the widow of a percussion-cap maker, aged 59 years...."

I was informed by this lady's son that she had not been in the neighborhood of Broad Street for many months.  A cart went from Broad Street to West End every day, and it was the custom to take out a large bottle of the water from the pump in Broad Street, as she preferred it.  The water was taken on Thursday, 31st August, and she drank of it in the evening, and also on Friday.  She was seized with cholera on the evening of the latter day, and died on Saturday, as the above quotation from the register shows.

A niece, who was on a visit to this lady, also drank of the water; she returned to her residence, in a high and healthy part of Islington, was attacked with cholera, and died also.  There was no cholera at the time, either at West End or in the neighborhood where the niece died.  Besides these two persons, only one servant partook of the water at Hampstead West End, and she did not suffer, or, at least, not severely....

The deaths which occurred during this fatal outbreak of cholera are indicated in the accompanying map, as far as I could ascertain them.

Map Showing the Situation of the Deaths in and around Broad Street, Golden Square
["Spot" map displayed by John Snow at a meeting of the Epidemiological Society of London on Dec 4, 1854]

...All the deaths from cholera which were registered in the six weeks from 19th August to 30th September [1854] within this locality ... are shown in the map by a black line in the situation of the house in which it occurred, or in which the fatal attack was contracted....

It requires to be stated that the water of the pump in Marlborough Street, at the end of Carnaby Street [6 on the map above], was so impure that many people avoided using it.  And I found that the persons who died near this pump in the beginning of September, had water from the Broad Street pump.  With regard to the pump in Rupert Street [7 on the map above], it will be noticed that some streets which are near to it on the map, are in fact a good way removed, on account of the circuitous road to it.  These circumstances being taken into account, it will be observed that the deaths either very much diminished, or ceased altogether, at every point where it becomes decidedly nearer to send to another pump than to the one in Broad Street....

In some of the instances, where the deaths are scattered a little further from the rest on the map, the malady was probably contracted at a nearer point to the pump.  A cabinet-maker, who ... worked in Broad Street.  A boy also who ... went to the National school at the end of Broad Street, and having to pass the pump, probably drank of the water.  A tailor, who ... spent most of his time in Broad Street.  A woman [who] had been nursing a person who died of cholera in Marshall Street.  A little girl, who died in Ham Yard, and another who died in Angel Court ... went to the school in Dufour's Place, Broad Street, and were in the habit of drinking the pump-water, as were also a child from Naylor's Yard, and several others, who went to this and other schools near the pump in Broad Street.  A woman who ... had been occupied for two days preceding her illness at the public washhouses near the pump, and used to drink a good deal of water whilst at her work; the water drank there being sometimes from the pump and sometimes from the cistern....

The following table exhibits the chronological features of this terrible outbreak of cholera.


...The greatest number of attacks in any one day occurred on the 1st of September, immediately after the outbreak commenced.  The following day the attacks fell from one hundred and forty-three to one hundred and sixteen, and the day afterwards to fifty-four.  A glance at the above table will show that the fresh attacks continued to become less-numerous every day.  On September the 8th -- the day when the handle of the pump was removed -- there were twelve attacks....

There is no doubt that the mortality was much diminished, as I said before, by the flight of the population, which commenced soon after the outbreak; but the attacks had so far diminished before the use of the water was stopped, that it is impossible to decide whether the well still contained the cholera poison in an active state, or whether, from some cause, the water had become free from it....

The water at the time of the cholera contained impurities of an organic nature, in the form of minute whitish flocculi visible on close inspection to the naked eye, as I before stated.  Dr. Hassall, who was good enough to examine some of this water with the microscope, informed me that these particles had no organized structure, and that he thought they probably resulted from decomposition of other matter.  He found a great number of very minute oval animalcules in the water, which are of no importance, except as an additional proof that the water contained organic matter on which they lived....

Vibrio cholerae

Whether the impurities of the water were derived from the sewers, the drains, or the cesspools, of which latter there are a number in the neighborhood, I cannot tell....  A very important point in respect to this pump-well is that the water passed with almost everybody as being perfectly pure, and it did in fact contain a less quantity of impurity than the water of some other pumps in the same parish, which had no share in the propagation of cholera. We must conclude from this outbreak that the quantity of morbid matter which is sufficient to produce cholera is inconceivably small, and that the shallow pump-wells in a town cannot be looked on with too much suspicion, whatever their local reputation may be....

Communication of Cholera by Means of the Water of Rivers Which Receive the Contents of The Sewers
All the instances of communication of cholera through the medium of water ... have resulted from the contamination of a pump-well, or some other limited supply of water; and the outbreaks of cholera connected with the contamination, though sudden and intense, have been limited also; but when the water of a river becomes infected with the cholera evacuations emptied from on board ship, or passing down drains and sewers, the communication of the disease, though generally less sudden and violent, is much more widely extended; more especially when the river water is distributed by the steam engine and pipes connected with water-works.

Cholera may linger in the courts and alleys crowded with the poor..., but I know of no instance in which it has been generally spread through a town or neighbourhood, amongst all classes of the community, in which the drinking water has not been the medium of its diffusion.  Each epidemic of cholera in London has borne a strict relation to the nature of the water-supply of its different districts, being modified only by poverty, and the crowding and want of cleanliness which always attend it.


This table [TABLE II] shows that in the greater part of Southwark, which was supplied with worse water than any other part of the metropolis, the mortality from cholera was also much higher than anywhere else.  The other south districts, supplied with water obtained at points higher up the Thames, and containing consequently less impurity, were less affected....

Influence of the Water Supply on the Epidemic of 1849, in London
Between 1839 and 1849 many changes took place in the water-supply of London. The Southwark Water Company united with the South London Water Company, to form a new Company under the name of the Southwark and Vauxhall Company. The water works at London Bridge were abolished, and the united company derived their supply from the Thames at Battersea Fields, about half-a-mile above Vauxhall Bridge. The Lambeth Water Company continued to obtain their supply opposite to Hungerford Market; but they had established a small reservoir at Brixton.

But whilst these changes had been made by the water companies, changes still greater had taken place in the river, partly from the increase of population, but much more from the abolition of cesspools and the almost universal adoption of waterclosets in their stead.  The Thames in 1849 was more impure at Battersea Fields than it had been in 1839.

A glance at the table shows that in every district to which the supply of the Southwark and Vauxhall, or the Lambeth Water Company extends, the cholera was more fatal than in any other district whatever.  The only other water company deriving a supply from the Thames, in a situation where it is much contaminated with the contents of the sewers, was the Chelsea Company.  But this company, which supplies some of the most fashionable parts of London, took great pains to filter the water before its distribution, and in so doing no doubt separated, amongst other matters, the greater portion of that which causes cholera.  On the other hand, although the Southwark and Vauxhall and the Lambeth Water Companies professed to filter the water, they supplied it in a most impure condition....

New Water Supply of the Lambeth Company
London was without cholera from the latter part of 1849 to August 1853.  During this interval an important change had taken place in the water supply of several of the south districts of London.  The Lambeth Company removed their water works, in 1852, from opposite Hungerford Market to Thames Ditton; thus obtaining a supply of water quite free from the sewage of London.

The districts supplied by the Lambeth Company are, however, also supplied, to a certain extent, by the Southwark and Vauxhall Company, the pipes of both companies going down every street, in the places where the supply is mixed....  In consequence of this intermixing of the water supply, the effect of the alteration made by the Lambeth Company on the progress of cholera was not so evident, to a cursory observer, as it would otherwise have been....


Intimate Mixture of the Water Supply of the Lambeth with That of the Southwark and Vauxhall Company
[T]he intermixing of the water supply of the Southwark and Vauxhall Company with that of the Lambeth Company, over an extensive part of London, admitted of the subject being sifted in such a way as to yield the most incontrovertible proof on one side or the other....

The pipes of each Company go down all the streets, and into nearly all the courts and alleys.  A few houses are supplied by one Company and a few by the other, according to the decision of the owner or occupier at that time when the Water Companies were in active competition.  In many cases a single house has a supply different from that on either side.  Each company supplies both rich and poor, both large houses and small; there is no difference either in the condition or occupation of the persons receiving the water of the different Companies.

Now it must be evident that, if the diminution of cholera, in the districts partly supplied with the improved water, depended on this supply, the houses receiving it would be the houses enjoying the whole benefit of the diminution of the malady, whilst the houses supplied with the water from Battersea Fields would suffer the same mortality as they would if the improved supply did not exist at all.

As there is no difference whatever, either in the houses or the people receiving the supply of the two Water Companies, or in any of the physical conditions with which they are surrounded, it is obvious that no experiment could have been devised which would more thoroughly test the effect of water supply on the progress of cholera than this, which circumstances placed ready made before the observer.

Opportunity Thus Afforded of Gaining Conclusive Evidence of the Effect of the Water Supply on the Mortality from Cholera
The experiment, too, was on the grandest scale.  No fewer than three hundred thousand people of both sexes, of every age and occupation, and of every rank and station, from gentlefolks down to the very poor, were divided into two groups without their choice, and, in most cases, without their knowledge; one group being supplied with water containing the sewage of London, and, amongst it, whatever might have come from the cholera patients, the other group having water quite free from such impurity.

To turn this grand experiment to account, all that was required was to learn the supply of water to each individual house where a fatal attack of cholera might occur....

I commenced my inquiry about the middle of August with two sub-districts of Lambeth, called Kennington, first part, and Kennington, second part.  There were forty-four deaths in these sub-districts down to 12th August, and I found that thirty-eight of the houses in which these deaths occurred were supplied with water by the Southwark and Vauxhall Company, four houses were supplied by the Lambeth Company, and two had pump-wells on the premises and no supply from either of the Companies.

Account of the Inquiry for Obtaining This Evidence
...I pursued my inquiry over the various other sub-districts of Lambeth, Southwark, and Newington, where the supply of the two Water Companies is intermixed, with a result very similar to that already given....

The inquiry was necessarily attended with a good deal of trouble. There were very few instances in which I could at once get the information I required.  Even when the water-rates are paid by the residents, they can seldom remember the name of the Water Company till they have looked for the receipt.  In the case of working people who pay weekly rents, the rates are invariably paid by the landlord or his agent, who often lives at a distance, and the residents know nothing about the matter.  It would, indeed, have been almost impossible for me to complete the inquiry, if I had not found that I could distinguish the water of the two companies with perfect certainty by a chemical test....

Result of the Inquiry as Regards the First Four Weeks of the Epidemic of 1854
...There were three hundred and thirty-four deaths from cholera in these four weeks, in the districts to which the water supply of the Southwark and Vauxhall and the Lambeth Company extends.  Of these it was ascertained, that in two hundred and eighty-six cases the house where the fatal attack of cholera took place was supplied with water by the Southwark and Vauxhall Company, and in only fourteen cases was the house supplied with the Lambeth Company's water; in twenty-two cases the water was obtained by dipping a pail directly into the Thames, in four instances it was obtained from pump-wells, in four instances from ditches, and in four cases the source of supply was not ascertained, owing to the person being taken ill whilst traveling, or from some similar cause....

It is extremely worthy of remark, that whilst only five hundred and sixty-three deaths from cholera occurred in the whole of the metropolis, in the four weeks ending 5th August, more than one half of them took place amongst the customers of the Southwark and Vauxhall Company, and a great portion of the remaining deaths were those of mariners and persons employed amongst the shipping in the Thames, who almost invariably draw their drinking water direct from the river.

It may, indeed, be confidently asserted, that if the Southwark and Vauxhall Water Company had been able to use the same expedition as the Lambeth Company in completing their new works, and obtaining water free from the contents of sewers, the late epidemic of cholera would have been confined in a great measure to persons employed among the shipping, and to poor people who get water by pailsful direct from the Thames or tidal ditches....

Result of the Inquiry ss Regards the First Seven Weeks of the Epidemic of 1854
As the epidemic advanced, the disproportion between the number of cases in houses supplied by the Southwark and Vauxhall Company and those supplied by the Lambeth Company, became not quite so great, although it continued very striking....

The following is the proportion of deaths to 10,000 houses, during the first seven weeks of the epidemic, in the population supplied by the Southwark and Vauxhall Company, in that supplied by the Lambeth Company, and in the rest of London.


The mortality in the houses supplied by the Southwark and Vauxhall Company was therefore between eight and nine times as great as in the houses supplied by the Lambeth Company; and it will be remarked that the customers of the Lambeth Company continued to enjoy an immunity from cholera greater than the rest of London which is not mixed up as they are with the houses supplied by the Southwark and Vauxhall Company....

Assent of the Medical Profession to the Influence of Polluted Water on the Mortality from Cholera
After the Registrar-General alluded, in the "Weekly Return" of 14th October last, to the very conclusive investigation of the effects of polluted water in the south districts of London, there was a leading article, in nearly all the medical periodicals, fully admitting the influence of the water on the mortality from cholera.  It may therefore be safely concluded that this influence is pretty generally admitted by the profession.

It must not be disguised, however, that medical men are not yet generally convinced that the disease is actually communicated from person to person by the morbid matter being swallowed in the drinking water, or otherwise.

It used to be the custom of medical authors to speak of three kinds of causes of a disease, viz. predisposing, exciting, and proximate causes.  The proximate causes have been given up, as being the diseases themselves; but authors still divide causes into predisposing and exciting ones.  It may be remarked, however, that in treating of certain communicable diseases, the cause of which is thoroughly understood, as syphilis and the itch, predisposing causes are never mentioned; and that they are rarely alluded to in treating of smallpox, measles, and scarlet fever, whilst they continue to be appealed to in explanation of the various continued fevers.

Now many medical men, whilst they admit the influence of polluted water on the prevalence of cholera, believe that it acts by predisposing or preparing the system to be acted on by some unknown cause of the disease existing in the atmosphere or elsewhere.  The following amongst other reasons prove, however, that opinion cannot long halt here, and that, if the effect of contaminated water be admitted, it must lead to the conclusion that it acts by containing the true and specific cause of the malady....

Answers to Certain Objections
There are one or two objections to the mode of communication of cholera which I am endeavouring to establish, that deserve to be noticed.

Messrs. Pearse and Marston state, in their account of the cases of cholera treated at the Newcastle Dispensary in 1853, that one of the dispensers drank by mistake some rice-water evacuation without any effect whatever.

In rejoinder to this negative incident, it may be remarked, that several conditions may be requisite to the communication of cholera with which we are as yet unacquainted....  Syphilis we know is only communicable in its primary stage, and vaccine lymph must be removed at a particular time to produce its proper effects.  In the incident above mentioned, the large quantity of the evacuation taken might even prevent its action.  It must be remembered that the effects of a morbid poison are never due to what first enters the system, but to the crop or progeny produced from this during a period of reproduction, termed the period of incubation; and if a whole sack of grain, or seed of any kind, were put into a hole in the ground, it is very doubtful whether any crop whatever would be produced....
An objection that has repeatedly been made to the propagation of cholera through the medium of water, is, that every one who drinks of the water ought to have the disease at once.
This objection arises from mistaking the department of science to which the communication of cholera belongs, and looking on it as a question of chemistry, instead of one of natural history, as it undoubtedly is.

It cannot be supposed that a morbid poison, which has the property, under suitable circumstances, of reproducing its kind, should be capable of being diluted indefinitely in water, like a chemical salt; and therefore it is not to be presumed that the cholera-poison would be equally diffused through every particle of the water.  The eggs of the tape-worm must undoubtedly pass down the sewers into the Thames, but it by no means follows that everybody who drinks a glass of the water should swallow one of the eggs....

It is not necessary to oppose any other theories in order to establish the principles I am endeavouring to explain, for the field I have entered on was almost unoccupied.  The best attempt at explaining the phenomena of cholera, which previously existed, was probably that which supposed that the disease was communicated by effluvia given off from the patient into the surrounding air, and inhaled by others into the lungs; but this view required its advocates to draw very largely on what is called predisposition, in order to account for the numbers who approach near to the patient without being affected, whilst others acquire the disease without any near approach.  It also failed entirely to account for the sudden and violent outbreaks of the disease, such as that which occurred in the, neighbourhood of Golden Square.

Another view having a certain number of advocates is, that cholera depends on an unknown something in the atmosphere which becomes localized, and has its effects increased by the gases given off from decomposing animal and vegetable matters.  This hypothesis is, however, rendered impossible by the motion of the atmosphere, and, even in the absence of wind, by the laws which govern the diffusion of aeriform bodies; moreover, the connection between cholera and offensive effluvia is by no means such as to indicate cause and effect; even in London, as was before mentioned, many places where offensive effluvia are very abundant have been visited very lightly by cholera, whilst ... comparatively open and cleanly districts ... have suffered severely....

Mr. John Lea, of Cincinnati, has advanced what he calls a geological theory of cholera.  He supposes that the cholera poison, which he believes to exist in the air about the sick, requires the existence of calcareous or magnesian salts in the drinking-water to give it effect.  This view is not consistent with what we know of cholera, but there are certain circumstances related by Mr. Lea which deserve attention.  He says that, in the western districts of the United States, the cholera ... attacked with deadly effect those who use ... calcareous water, while it passed by those who used sandstone or soft water.  He gives many instances of towns suffering severely when river water was used, whilst others, having only soft spring water or rain water, escaped almost entirely; and he states that there has been scarcely a case of cholera in families who used only rain water.

The rivers, it is evident, might be contaminated with the evacuations, whilst it is equally evident that the rain water could not be so polluted.  As regards sand and all sandstone formations, they are well known to have the effect of oxidizing and thus destroying organic matters; whilst the limestone might not have that effect, although I have no experience on that point.  The connection which Mr. Lea has observed between cholera and the water is highly interesting, although it probably admits of a very different explanation from the one he has given.....

The Effect of Season on the Prevalence of Cholera
Each time when cholera has been introduced into England in the autumn, it has made but little progress, and has lingered rather than flourished during the winter and spring, to increase gradually during the following summer, reach its climax at the latter part of summer, and decline somewhat rapidly as the cool days of autumn set in. In most parts of Scotland, on the contrary, cholera has each time run through its course in the winter immediately following its introduction.

I have now to offer what I consider an explanation, to a great extent, of these peculiarities in the progress of cholera.  The English people, as a general rule, do not drink much unboiled water, except in warm weather.  They generally take tea, coffee, malt liquor, or some other artificial beverage at their meals, and do not require to drink between meals, except when the weather is warm.

In summer, however, a much greater quantity of drink is required, and it is much more usual to drink water at that season than in cold weather.  Consequently, whilst the cholera is chiefly confined in winter to the crowded families of the poor, and to the mining population, who, as was before explained, eat each other's excrement at all times, it gains access as summer advances to the population of the towns, where there is a river which receives the sewers and supplies the drinking water at the same time; and, where pump-wells and other limited supplies of water happen to be contaminated with the contents of the drains and cesspools, there is a greater opportunity for the disease to spread at a time when unboiled water is more freely used.

In Scotland, on the other hand, unboiled water is somewhat freely used at all times to mix with spirits; I am told that when two or three people enter a tavern in Scotland and ask for a gill of whiskey, a jug of water and tumbler-glasses are brought with it.  Malt liquors are only consumed to a limited extent in Scotland, and when persons drink spirit without water, as they often do, it occasions thirst and obliges them to drink water afterwards.

There may be other causes besides the above which tend to assist the propagation of cholera in warm, more than in cold weather.  It is not unlikely that insects, especially the common houseflies, aid in spreading the disease....

Evidence That Plague, Yellow Fever, Dysentery, and Typhoid Fever Are
Communicated in the Same Way as Cholera
Since the latter part of 1848, when I first arrived at my present conclusions respecting the mode of communication of cholera, I have become more and more convinced that many other diseases are propagated in the same way.

When the plague visited this country, it was most fatal in London, York, Winchester, and certain other towns having a river of fresh water passing through them.  It resembled cholera also in being twice as fatal in the districts on the south of the Thames as in those on the north....

Although some of the lower parts of the City were supplied with water from the Thames, at the latter part of the sixteenth and throughout the seventeenth century, yet the greater part of London north of the Thames was supplied by fountains and conduits, conveying spring water from a distance....

The plague resembles cholera in being much promoted by crowding and want of personal cleanliness....

Yellow fever, which has been clearly proved ... to be a communicable disease, resembles cholera and the plague in flourishing best, as a general rule, on low alluvial soil, and also in spreading greatly where there is a want of personal cleanliness....

It was long ago observed, that dysentery was apparently propagated by the drinking of water containing excrementitious matters.  The frequent appearance of this disease in Millbank prison, when the Thames water was used, is a confirmation of this; and Dr. Bryson has lately related a number of instances where both dysentery and fever seemed to be occasioned by the water of the Yangtse-Kiang, the Canton river, and other rivers of China....

There are many facts which indicate that one at least of the continued fevers--the typhoid fever with ulceration of the small intestines-- is also propagated in the same way as cholera....

Instances in Which Ague  [Malaria]Was Caused by Impure Water
Intermittent fevers are so fixed to particular places that they have deservedly obtained the name of endemics.  They spread occasionally, however, much beyond their ordinary localities, and become epidemic.  Intermittent fevers are undoubtedly often connected with a marshy state of the soil; for draining the land frequently causes their disappearance.  They sometimes, however, exist as endemics, where there is no marshy land or stagnant water within scores of miles.

Towards the end of the seventeenth century, intermittent fevers were... attributed ... to noxious effluvia arising from marshes.  These supposed effluvia, or marsh miasmata, as they were afterwards called, were thought to arise from decomposing vegetable and animal matter; but, as intermittent fevers have prevailed in many places where there was no decomposing vegetable or animal matter, this opinion has been given up in a great measure; still the belief in miasmata or malaria of some kind, as a cause of intermittents, is very general.  It must be acknowledged, however, that there is no direct proof of the existence of malaria or miasmata, much less of their nature.

That preventive of ague, draining the land, must affect the water of a district quite as much as it affects the air, and there is direct evidence to prove that intermittent fever has, at all events in some cases, been caused by drinking the water of marshes....

Whether the unknown cause of ague has been produced in the system of a previous patient, like the pus of smallpox and the eggs of tapeworm, or whether it has been produced externally, there is, at present, no sufficient evidence to show...

The communication of ague from person to person has not been observed, and supposing this disease to be communicable, it may be so only indirectly, for the materies morbi eliminated from one patient may require to undergo a process of development or procreation out of the body before it enters another patient, like certain flukes infesting some of the lower animals, and procreating by alternate generations.

Measures Required for the Prevention of Cholera and Other Diseases Which Are Communicated in the Same Way
The measures which are required for the prevention of cholera, and all diseases which are communicated in the same way as cholera, are of a very simple kind.  They may be divided into those which may be carried out in the presence of an epidemic, and those which, as they require time, should be taken beforehand.

The measures which should be adopted during the presence of cholera may be enumerated as follows:--

1st.  The strictest cleanliness should be observed by those about the sick.  There should be a hand-basin, water, and towel, in every room where there is a cholera patient, and care should be taken that they are frequently used by the nurse and other attendants, more particularly before touching any food.

2nd.  The soiled bed linen and body linen of the patient should be immersed in water as soon as they are removed, until such time as they can be washed, lest the evacuations should become dry, and be wafted about as a fine dust.  Articles of bedding and clothing which cannot be washed, should be exposed for some time to a temperature of 212 degrees or upwards.

3rd.  Care should be taken that the water employed for drinking and preparing food (whether it come from a pump-well, or be conveyed in pipes) is not contaminated with the contents of cesspools, house-drains, or sewers; or, in the event that water free from suspicion cannot be obtained, is should be well boiled, and, if possible, also filtered.

Works are in progress for supplying a great part of London with water from the Thames, obtained, like that of the Lambeth Company, above Teddington Lock.  Although this is not the best possible source for supplying a large town, it is a great improvement on the practice of many of the water companies; and the water, owing to filtration, and especially to its detention in large reservoirs, will probably be quite salubrious:  at all events it will be much safer than that of the shallow pump-wells of London, which are fed from very polluted sources....
4th.  When cholera prevails very much in the neighbourhood, all the provisions which are brought into the house should be well washed with clean water, and exposed to a temperature of 212 degrees Fahrenheit; or at least they should undergo one of these processes, and be purified either by water or by fire.  By being careful to wash the hands, and taking due precautions with regard to food, I consider that a person may spend his time amongst cholera patients without exposing himself to any danger.

5th.  When a case of cholera or other communicable disease appears among persons living in a crowded room, the healthy should be removed to another apartment, where it is practicable, leaving only those who are useful to wait on the sick.

6th.  As it would be impossible to clean out coal-pits, and establish privies and lavatories in them, or even to provide the means of eating a meal with anything like common decency, the time of working should be divided into periods of four hours instead of eight, so that the pit-men might go home to their meals, and be prevented from taking food into the mines.

7th.  The communicability of cholera ought not to be disguised from the people, under the idea that the knowledge of it would cause a panic, or occasion the sick to be deserted.

British people would not desert their friends or relatives in illness, though they should incur danger by attending to them; but the truth is, that to look on cholera as a "catching" disease, which one may avoid by a few simple precautions, is a much less discouraging doctrine than that which supposes it to depend on some mysterious state of the atmosphere in which we are all of us immersed and obliged to breathe.

The measures which can be taken beforehand to provide against cholera and other epidemic diseases, which are communicated in a similar way, are--

8th.  To effect good and perfect drainage.

9th.  To provide an ample supply of water quite free from contamination with the contents of sewers. cesspools, and house-drains, or the refuse of people who navigate the rivers.

10th.  To provide model lodging-houses for the vagrant class, and sufficient house room for the poor generally.

The great benefit of the model lodging-houses arises from the circumstance that the apartments for cooking, eating, and sleeping, are distinct, and that all the proper offices which cleanliness and decency require are provided.  The very poor who choose to avail themselves of these institutions suffer a rate of mortality as low as that of the most opulent classes.  The public wash-houses, which enable poor persons to wash the soiled linen of the sick or the healthy, without doing it in the midst of the plates and dishes and provisions of the family, are well calculated to prevent the spread of disease.
11th.  To inculcate habits of personal and domestic cleanliness among the people everywhere.

12th.  Some attention should undoubtedly be directed to persons, and especially ships, arriving from infected places, in order to segregate the sick from the healthy.  In the instance of cholera, the supervision would generally not require to be of long duration....

The measures which are intended to prevent disease should be founded on a correct knowledge of its causes.  For want of this knowledge, the efforts which have been made to oppose cholera have often had a contrary effect.  In 1849, for instance, the sewers of London were frequently flushed with water,-- a measure which was calculated to increase the disease in two ways:  first, by driving the cholera evacuations into the river before there was time for the poison to be rendered inert by decomposition; and second, by making increased calls on the various companies for water to flush the sewers with,-- so that the water which they sent to their customers remained for a shorter time in the reservoirs before being distributed....

I feel confident, however, that by attending to the above-mentioned precautions, which I consider to be based on a correct knowledge of the cause of cholera, this disease may be rendered extremely rare, if indeed it may not be altogether banished from civilised countries.  And the diminution of mortality ought not to stop with cholera.

The deaths registered under the name of typhus consist chiefly of the typhoid fever mentioned above. Its victims are composed chiefly of persons of adult age, who are taken away from their families and connections.  In 1847 upwards of 20,000 deaths were registered in England from typhus, and in 1848 upwards of 30,000 deaths.  It is probable that seven times as many deaths have taken place from typhus as from cholera, since the latter disease first visited England in 1831; and there is great reason to hope that this mortality may in future be prevented by proper precautions, resulting from a correct knowledge of the mode of communication of the malady.

Go to:
  • "Observations on the Filth of the Thames," a letter to the Times of London (July 7, 1855) by Professor Michael Faraday (1791-1867)
  • "Monster Soup commonly called Thames Water, being a correct representation of that precious stuff doled out to us..." (ca. 1828) by William Heath (1795-1840)
  • News articles from the Chicago Tribune:
    • "They Deal in Death...," August 20, 1893
    • "Caused by Microbes...," November 23, 1893
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