Commentary: Behind the Broad Street pump: aetiology, epidemiology and prevention of cholera in mid-19th century Britain

Introductory epidemiology text books and courses generally contain little epidemiological history, but an exception is made for the story of John Snow, the water-born transmission of cholera, and the handle of the Broad Street pump.1–5 Snow’s 1855 book, On The Mode Of Communication Of Cholera,6 is indeed a beautiful demonstration of ‘the epidemiological imagination’7 in action, and continues to provide example and inspiration to people entering the discipline. However, it appeared amidst a veritable spate of speculation, experiment, investigation and recommendations regarding cholera, and some of these less celebrated (at least now) contributions remain instructive. Therefore, in the current issue of the International Journal of Epidemiology we reprint a section of Dr John Sutherland’s report for the General Board of Health on the 1848–1849 British cholera epidemic (Figure 1), together with a series of commentaries.8–10 The extracts from Sutherland’s report include his investigation of the effect of water source on cholera risk in Salford, Manchester, which was briefly referred to by Snow6 and has occasionally been recognized as a seminal investigation.11,12 The discussion by Sutherland of the implications of his finding are clearly at variance with those of Snow, who more strongly emphasized the necessary transmissible element in generating cholera (and thus in triggering epidemics), but Sutherland’s utilization of quantitative data is striking. As with (virtually) all scientific advances, Snow’s work did not emerge from a vacuum, and this background has been explored from various perspectives.13–23 The proto-epidemiological approaches to cholera in the mid-19th century have continuing implications for epidemiological theory and practice, and this does not only apply to the investigations now seen to have contributed to us reaching the correct conclusions. The efforts of many of Snow’s predecessors and contemporaries were seen, at the time, as of at least (and often greater) importance than those of Snow.13,14,24,25 The contributions of those who are now excluded from potted histories of epidemiology are certainly worth revisiting. Cholera first reached Britain from continental Europe in October 1831 and during the subsequent year resulted in over 30 000 deaths.26 The disease had probably been endemic in India27 and from 1817 onwards spread inexorably towards Britain. The Lancet devoted 44 pages of its 19 November 1831 issue to the arrival of cholera in Britain.27 Regarding the origin of cholera, the Lancet concluded that: We can only suppose the existence of a poison which progresses independently of the wind, of the soil, of all conditions of the air, and of the barrier of the sea; in short, one that makes mankind the chief agent for its dissemination.27 (Box 1) PROOFS OF COMMUNICATION OF CHOLERA BY MAN We shall classify our proofs of communication under the following heads of: The coincidence between the irruption of the disease in previously-uninfected places, with the arrival of ships, of caravans of fugitives or pilgrims, of individuals, and with the progress of armies. Examples of the coincidence between the occurrence of cholera in individuals, and their contact with others actually labouring under the disease. Examples of immunity afforded by seclusion in the midst of an unhealthy district. The Lancet, 19 November 1831.27 Others pointed out that cholera in India followed the pathsof rivers. After indicating that they were using contagion and infection synonymously (because some authorities used these terms to designate distinct transmission modes13), the Lancet also discussed evidence against the contagious nature of cholera, but they dismissed this and advocated quarantine and sanitary measures. The viewpoint of the Lancet was not one widely shared in the medical and related professions, and a variety of non-contagious aetiologies—generally glossed as ‘miasma theories’—were advanced.13,26,27 Several studies of local outbreaks were carried out, and while some hinted at both contagion and transmission by water, of that the disease was non-contagious and the cholera in a the of between and and that the did not the disease to at all contagious and only it to The little by the of these and was a that the disease was indeed was in local to the of cholera they people to the cholera were and the to the or in water from the quarantine were in both the and Britain with recommendations for the of and in with approaches to as the of and to the the of cholera in in the of the local Board of Health was also the of a in which cholera was referred to as a contagious and quarantine were Dr who the first of the and who in The of the Cholera in in (Figure that many medical the disease was from to by the communication of a of which we also the nature the cholera an and but under and of from to a all the of cholera in in and John from regarding and water which to provide evidence of the nature of the epidemiological and approaches to cholera were in the of some of the contagious nature of some in and but with little of the century that was but one in the was widely The for epidemic cholera was as its and it was the arrival of cholera actually with an in or between of an in for this The of were often discussed in terms of and were as or and The were those which the to towards a as the seen as to cholera to in the of agent and by the the under the of the The clearly a theory of the of cholera, in some to the of conditions as disease in However, of a did not an of for some it was that to a of to which resulted in the necessary of a a was a necessary of disease. followed from or in a than the one we John Sutherland some that water the poison of cholera, while some that water as a of the in the as the or to Others that the at the of the The of of and certainly that of of on the of an of the of cholera a variety of on (Box together with for and from the Board of in and and from water, and all from and have it less than and in the of not or in a of As out, the of the disease also that was only that and to a in its As with from the to the and disease was seen to an of cholera, with the of a many authorities followed in that ‘the of in the cholera than our approaches to and an in were for its As the of the of in a has been that a and as from a those who are with it less to and discussion of the and of cholera in to the of the disease. of on the in October was by of and who concluded of the against the of its contagious was a and cholera on the with was by the to of cholera on the during the concluded that the and of was to the that the disease is The of epidemic cholera to Britain in and the in in the disease for and also for the evidence related to the spread of cholera towards Europe and the this in November that of and by to the of contagious The the the is the of that agent which with the disease. the only in his which can we to effect with and cholera, which in was in is in at and now the of from the of cholera who was and who was during the and was not the of (and the as but the only that are now celebrated are the by John and the a of the as to the was the of and of for the cholera together with and of outbreaks which only by the transmission of an agent of disease. from cholera by and to the in and which to in water an in concluded that is not that all the in were by the water, but that the of in short, it was the of the cholera the water which the disease to spread its discussed the first of cholera in during which more than people in one while in were that element have been shared between these places, the water that was was and one ‘the poison to have been the of the who the in the water they was a is now as of his regarding the of cholera is in Mode of and its to the the of cholera is a of distinct this to by the of the and by the which is of the and of these in the and the they are the of the which is of and with its and the disease. the are only in the these are in the air, in the of in contact with of and and in the of are between the of and that water was not in all the of cholera, did not the of transmission in the while for this as a but less of and more that had the agent of element in the water, which and others in the water from the of the first (Figure The theory and various a of to the which to work concluded his by that had not evidence to his but of a to his that Snow’s on cholera while these were for and that Snow, had The with the that in Snow’s that is and in with the that the of the of the and the of its were all that was to his a the of the agent of cholera the element in its of and thus The of and were widely with as to the transmission and of in The in November as that cholera by water from an water is the which this poison its the it the water theory was with and of The of that the theory was referred to as Snow’s was with a example a in the Lancet in that a had the theory to that had his but that not made the in the of but as cholera were with and to the of more it a not to the of to from by a Others were by for his for in the and both and epidemiological data to their of the evidence they to the of the risk with water that to in report from the General Board of Health which and were in the evidence from Sutherland’s which we in this issue of the International Journal of and that in by were with water from a which and the of Of the of these that one of the of cholera a Dr of with was seen to with and that of who did not a all from the while of who used the were the investigation of John in his report as an for the General Board of was a between water and the occurrence of a but less with water Sutherland concluded that with to water from which the of or had the by the of water is the of in a report of in which many and were and the importance of water was not in the to the the investigations were carried John that the of water or water, than water, people against cholera, and his to the British in in water and cholera, a of cholera and the water of a of Of used water from a and used the using water were while in the using water were people to an of out of 30 for the people using water and out of for those using water, an a investigation by in during which cholera in using water from a while were seen in not using the these people to to a cholera of people using the on to of the in Broad the Board of Health had the from those to provide water to was to an in the of the but with the Broad Street handle this was of an epidemic (Figure is his by to a in the October issue of The from which Sutherland’s Street that water was a against cholera than against The of water was the element it to cholera or After his John on cholera, at least to the had to the data had from Dr regarding the of cholera in in and to John Sutherland’s investigation of the data from this to the General Board of not to John but Sutherland by for a transmission for also discussed the work of John the which has between cholera and the water is it probably of a than the one has The cholera in John to the investigations by in this issue of the International Journal of The background to these were the studies discussed which cholera to water a water and had John Snow’s investigations of a and with than the work they and clearly their as of century data in the General under the of to the between water and cholera indeed in John Sutherland’s report on the cholera epidemic these data are referred to as by the (Box John Sutherland’s report on the cholera epidemic in as the by the they certainly some which are thus that water from from cholera in the that the water from it was from cholera in the The in the by that have cholera had only been as as it was in the that their water from The were probably in some but is to that of is referred to that the thus that the in a of by the and with the in the of by the as to it is that the sanitary of the does not in the of the water by the it is to this evidence of the effect of the water, and of the of which has from its to on cholera by source of water and data to his celebrated on the a in which water was related to cholera risk that were and by was that have been which more the effect of water on the progress of cholera than epidemiology that: his in the from these water were was less of from the various water that water to the various of have been a less to the effect of the water many from one to the in which the of the and and those of the were that was little between those who water from one or the from the water of his was the in which to the The on to data from of Snow’s 1855 book, an many in those water from the and than those it from the The of the that in to but that it was not as As a the on first we that the referred to only in the with the and that this was the to the on a by Dr on the and its we that these had in all by the or this we the can for the to a a on while the and the of the and in to the that the and the and of the of had that those of which had in the the cholera epidemic to have from cholera during the and this to which the risk of both cholera and of also that the of the was related to cholera and a this with the of by data on the water for all cholera that in which were by both together with the of in the from which the his less it is to that the were a of during the first of the epidemic those water from the and to those water from the the is only to an from both to a of as in his 1855 the of water all of that to a the of the have the epidemiological of the of General Board of Health report a between water and cholera risk than which to the that the Board of Health to source of water The century cholera on to with the various studies discussed this that an of disease was for the of John in his report on the epidemic those water from and with those water from the with to the over water was a or of cholera that ‘the of water is to the the of its is of at least for John to indicating that those Sutherland who water as a but not one a cholera in a is to to some as as the of to the but to that we to disease we have a correct of its Sutherland for his of the and the of his action, that a in the of the was than the to the the is to now seen as or approaches to disease to the of of their regarding the of cholera, or the contagious nature of in the of Britain in and disease from the century that were by in their to the of the was now of disease the of British in the from the century to is not to from current of the of to the of at together with a of to in and in the of water and advocated the of water which not now seen as a The century the of cholera were often it to the that more was at than the of medical one of the of his and a of was by as with to regarding were contagious or the which it to some to their on all the has with are in and John The of contagion in various has often been discussed with a of that is in medical or scientific The of the of that has been in probably been to the is the in the on of its with The that on the or nature of disease on the of or of was a in the of the to these and was in an by the medical in of his than the of his that a between of and that the to the of epidemic and that the people their by quarantine and to the of and as and they were in the as they were and of in the The in this and thus the of the of an viewpoint during the first of the century can seen as an of the in and of this on century epidemiology (and its implications for and century have to the and of disease a of over the of from their and has to a of that were the of those from their of the between and is with many of both on and disease were that were contagious on than a from the to of disease. as of disease that a and were not between or that did not with the generally nature of a with to have of the many who have this are and but that in one of their they have from the makes it that at the on cholera and on the were a less some and were clearly in on in that his cholera and at by that not with or that approaches to contagious disease and of Snow’s 1855 to a of the British the and to the of the that the of and did not disease. was to that his theory of disease transmission not the of this issue and data from the to that the those in the were actually than those of the these data with a discussion of with his one from as of the as a a from the the of the that effect was seen in this for that also the of in is now ‘the of to and the the in the of a than the is probably they are less to and less to than following many and as a they not a his work on in the that evidence to were not or from their a century and a it was Snow’s on the of disease his as a that: it is to the of the of by the and of that for the of and not to the efforts of the of the as a was not in his on the of a it was to for a section on this in the report from which we extracts in this issue of the International Journal of were and indeed the of cholera in to the that they only John on the clearly had to his at the of his who a in as of cholera Sutherland that had of the contagion and had that quarantine was but a of local to against the his The water had a in in the of the water in in from water during the a of a water carried out a his water, while in the evidence that all the cholera in by a the have been for cholera, than As the of is not water to its by the has had the of it scientific have been has the has been with the and the of of all while has been and The of mid-19th century against the that cholera is an endemic disease in many of the of to cholera has not been mid-19th century cholera was seen to a disease of the was shared by those who cholera a disease by a and those who it as the of a of was the that cholera the was a to the of the The that the of as from which disease spread to the to a of the and to that to their concluded his it in to their the to to the of the this is one of our first and The we but we the of its of our we are all more related than we are to The of the in together by a of existence the in little that was with his by of or one it is that is with by a which at to a The has with some current on the of in has that of are not with the but with the and in this it is a that for the in the of the as to the more of the the of with of John a example of to by the of a that from was entering their water The an agent who that was but with the the and on at the water and that the with was and a of on a was with the cholera, and on the cholera in his at the to cholera in the mid-19th century the between and approaches has as discussed in the of the century the of cholera was a disease or one by which an was a of the mid-19th century this was less of an disease by water were for cholera, did this a but of John certainly in his 1855 that the theory also apply to and some evidence to these in the of transmission by but in a that now seen as more that was a disease of the as cholera and in the by and are of the that by the and of at the of the of the but these from the of the and their the discussion of the with to cholera in the century has to the who to for the the of Snow’s at least have been this as his and have that epidemiology from the of the of the mid-19th current approaches that and to with of as to the of while and that disease from their background to an epidemiology that to the of disease and in did for the of disease and was of approaches that disease to of the did not only apply to cholera or the of that the disease had generally been to of a as air, of and and a did not as had seen a of in some of the in the of the and the were as as in the of the in was the disease was to a of which the of with the for that the of cholera to was As a that an investigation of carried out between and than between and cholera, and we that has in the the that was and clearly that his example the of Snow’s did the agent from its generally as the who that cholera was of Snow’s discussion of the disease it that also that transmission or his one that water was the of cholera, for not it a at but only a or of the one of the the cholera and people the cholera agent were who and and for and the cholera was on but of than the of people and thus their As pointed out, people cholera to people generally their of cholera more to that of the this the of disease in and the of disease of the and that some and to to while can The element from this viewpoint is the importance of in for a in the in is that the of and to the and as a in as a to of its more from an the element is of is to and a of the and mid-19th century on cholera is was against a contagious nature for the or against water as an of only the who this of The importance of has more been referred to as in between and their in disease is from the of not from The of cholera transmission by John was one in which to disease but the of the this the of disease. this can between discussed and transmission was transmission was of has for for transmission is probably more by of water for and than by water to cholera in the disease can water in Snow’s or The and the of disease spread to transmission is against a background of on and the which and of water can the of cholera and thus the for probably for the outbreaks of cholera in the existence of which evidence in of in the of Snow, and their referred to the that many people who were to the cholera did not the and they this the existence of The to and indeed it was a by those a between and from this is the of that to disease in the of of disease to not the of who the disease a is to a terms is to one and that were of the a many of is a with is a The that of for many to were medical to with the of to the of the by and medical an this is not the was by the who also used to more than the a and were people of their nature in the of the of on disease that had a of by conditions not the is only on was recognized by as referred to his for a on the the not The to of the epidemic of the to approaches to cholera in the mid-19th with a of and as was the of the disease. little to or of or to in of infection as the was with epidemiological investigations that by and also recognized that the of contributions from as as and not the that a in a in with in in with to and of which in have to in in conditions were of to many but this was a of the in which were to those (and are many of conditions in which a variety of were by epidemiological or proto-epidemiological and it is that these were to the a in some of than the century does of that the to these conditions is to the of disease and on is the to finding this out the on did of as a of of cholera than that by John has not of cholera for the people in the that both and of the century as of in at least some of its on on the of cholera which their than on the which that the from in histories of in the century have those were with or the of cholera in the that was least to the is clearly has for approaches to in not us from that and and the for is an which to their in from Snow, from Snow, of The of the Cholera in in of the to cholera, in various of from Cholera in Broad The handle was the epidemic was and to have had the who these that the of the have of the to for with a of John for for and for John and for