Category Archives: Public Health

Infographic: Pregnancy Rates & Age of Consent Across the Globe [via Daily Infographic]

Source: Tim ____, Pregnancy Rates & Age of Consent Across the Globe [Infographic], Daily Infographic, December 26, 2014,

At a quick glance, a lower age of consent for sex seems to correlates somewhat with lower teen pregnancy rates. A close look at the developed parts of the world will show that it is actually sex education and access to contraception which attributes to lowered pregnancy rates. The first-world-countries with lower ages of consent usually have a more rigorous standard for healthy sex education and contraception access.

Looking at countries like China and India throws us for a loop though. With similar populations and geographic placement their pregnancy rates couldn’t be more different. China has had stringent one-child-policies for a while now. This lead to the unfortunate increase in abortions of female fetuses. China’s policies and attitudes are changing for the better now – and they’re able to keep teen pregnancy at bay as well. India on the other-hand has had extreme population booms the last few decades much attributed to the lack of sex education and contraception for small village populations.

The USA isn’t much better – our age of consent varies state by state. Sometimes as low as 14 years of age, other 18. Our sex education and contraception access also varies drastically across state lines. Some states have almost outright abandoned abortion access, and supply no help for young women on contraception costs.

What today’s infographic does tell us is that teen pregnancy is a health hazard for both mother and child. Access to education and medicine are crucial to keep women healthy no matter their county’s poverty level.

DataViz History: The Ghost Map: Myth-Making and Evolution of the Ghost Map

The Earliest Spot Map of All

Dr. John Snow did not draw a map until December, 1854; the first spot map was produced in September of that year by Edmund Cooper, an engineer for the Metropolitan Commission of Sewers (see map below). Cooper’s investigation resulted from public complaints linking the sewers to the cholera outbreak. Rumors held sway that sewer works had disturbed the soil of an ancient pit where bodies had been buried during the plague of 1665. Many feared that this process had freed or generated noxious gases that caused the cholera. Some alleged further that cholera deaths had been especially numerous in houses next to gully-holes, the openings through which sewer gases were vented to the surface.[SOURCE]

In response, on Sept 26, 1854, the Commission held a special “court” in Greek Street, Soho, as The Times of London duly recorded the next day: “Mr Cooper had prepared a plan which accompanied his report, and on the plan a distinguishing mark was affixed, showing the houses in which death had occurred.” From his study of this map, and of the sewers themselves, Cooper concluded that the houses nearest the gully-holes had no greater number of deaths than houses not so situated. The sewers of the area where most of the deaths were clustered were in reasonable condition. The drains of the houses of the region were in generally bad condition — with many cesspools and deteriorating brickwork — and most of the houses had not taken advantage of the opportunity to connect their drains to the recently constructed sewers. Broad Street was served by two non-connecting sewers, a new one and an old one; but the numbers of deaths appeared to be equally divided between the parts of the street served by the two different sewers. Few deaths had occurred near the old plague-pit. The sewers that drained the plague-pit area flowed northward to Regent Street, where there had been few, if any, cases of cholera.

The chairman of the commission accordingly concluded, as reported by The Times of London, that “the sewers were not the cause of the cholera; that they were not in any way connected with the disease; but that the real cause of the calamitous occurrences in the locality … was the filthy and undrained state of the houses.” The commissioners expressed their hopes that these facts would be widely circulated to allay public fears.

In his report, Cooper added: “Since the outbreak, six men have been employed in these lines of sewers getting up information on this subject, all of whom, I am glad to state, are quite healthy, and entirely free from disease.” Thus, he suggested, sewer gases were unlikely to spread cholera.

Cooper’s plan appears to be the first cholera-death spot map of the Broad Street area. Moreover, his plan accounted for 316 deaths (all those recorded in the registrar general’s weekly returns to Sept 9), far more than the 83 deaths that Snow had investigated during the first week of September. It also appears from Cooper’s report that he, unlike Snow, used his map as an analytical investigative tool. Until Cooper had constructed and examined his map, he could not know whether or not more deaths had occurred close to the sewer gully holes. Indeed, he may have been the first 19th century cartographer to have used a disease map in this fashion.

Just as Snow had an agenda in drawing his maps (to implicate a contaminated pump), the sewer commission also had an agenda — to clear the gully holes and sewer excavations of suspicion. The sewers, they were happy to report, had done nothing to increase mortality in this fearful epidemic. Cooper called attention to the number of deaths in Broad Street, but apparently neither Cooper nor any of the other commissioners noticed any peculiar concentration of spots around the corner of Broad and Cambridge Streets (where the now-famous pump was located). Simply plotting deaths on a map did not lead the commission to Snow’s interpretation of the facts.

Edmund Cooper's Map

(Above) Edmund Cooper’s map of the Broad Street cholera epidemic made for the Metropolitan Commission of Sewers, September 1854. Inset: the Broad Street pump and surrounding addresses. Cooper designated each affected house by a large solid bar, and the cholera deaths occurring in each house by thin lines.

Snow’s investigation

The officials of St James’s parish (where in Golden Square is located) were aware that their locality had suffered a cholera outbreak of unusual intensity, about 500 deaths having occurred in the 10 days from Aug 31 to Sept 9, 1854, in an area of only a few square blocks. In November of that year, they appointed a cholera inquiry committee to examine the event, and asked Snow to join them. One of his tasks was to write a report on the local water supply, which he submitted on Dec 12, 1854. About a month later, Snow published a detailed monograph on the mode of communication of cholera, which included a discussion of the Broad Street outbreak.  Internal evidence suggests that Snow completed the account in his monograph before he wrote his report to the parish committee. In any event, the two accounts of his methods parallel are very similar, and accord with his brief, earlier account, published in Sept 23, 1854.

Snow had observed cholera first-hand in 1831 as an apprentice surgeon-apothecary, but he seems not to have questioned prevailing theories of cholera pathology and transmission until 1848-49, when he formulated a theory quite at odds with the then-dominant views. Snow argued that cholera was a localized disease of the gut, and that its symptoms were entirely the result of fluid loss. The causal agent, he reasoned, must enter by mouth, multiply within the gut, and then spread to others by the fecal-oral route. In his 1855 monograph he suggested that the structure of the unknown agent was that of a cell but, in the absence of microscopic evidence, he avoided speculation on its exact nature. While direct contact with contaminated bedclothes, for example, could explain cholera’s spread within a household and other confined spaces, Snow deduced that the transmission of the disease across greater distances was due to drinking water contaminated with raw sewage containing the specific cholera poison. Snow described two local outbreaks of cholera in south London in 1849 that seemed to suggest strongly a water-borne route.

When epidemic cholera next arrived in England in 1853-54, Snow realized that he had an opportunity to test his hypothesis on a grand scale. Two competing water companies had laid pipes up the same streets in several south London districts. In the 1848-49 epidemic, both companies had drawn upon water from the River Thames that had been contaminated by sewage. By 1853, one company (Southwark and Vauxhall) still supplied contaminated water, while the other company (Lambeth) had moved its intake source upstream to a fairly clean section of the river. When Snow learned of his change in the water supply, he realized that this arrangement constituted a superb natural experiment.  He undertook door-to-door investigations to relate cholera mortality to the source of water and found greater mortality among those drinking the water supplied by the Southwark and Vauxhall company, and made these data the centerpiece of the 1855 edition of his monograph. It was this investigation in south London that Snow suspended for several days at the beginning of September to investigate the severe localized outbreak near Golden Square.

Because he already had a hypothesis, Snow immediately investigated the water supply. The piped water was supplied by a company that drew its water from an unpolluted section of the Thames; and he knew from his own experience of living in the area that most residents preferred pump water. Moreover, his study of earlier outbreaks led him to conclude that a sharp localized outbreak pointed to a contaminated pump or well rather than a problem with the general water supply.

He turned his attention to the five pumps near Golden Square, finding that most of them contained impurities visible to the naked eye. By contrast, when Snow inspected the Broad Street pump water, on Sept 3, it looked clear; but a local resident reported that its water had smelled offensive just the day before. On Sept 5, Snow obtained from the General Register Office a list of the 83 deaths ascribed to cholera in the Golden Square area since Aug 31. In his own words:

On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the [Broad Street] pump. There were only ten deaths in houses situated decidedly nearer to another street-pump. In five of these cases the families of the decreased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pumps which were nearer. In three other cases, the deceased were children who went to school near the pump in Broad Street …

With regard to the deaths occurring in the locality belonging to the pump, there were 61 instances in which I was informed that the deceased persons used to drink the pump water from Broad Street, either constantly or occasionally …

The result of the inquiry, then, is, that there was been no particular outbreak or prevalence 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 the 7th inst [Sept 7], and represented the above circumstances to them. In consequence of what I said, the handle of the pump was removed on the following day.

Thus, Snow’s initial suspicion of the Broad Street pump was a deduction based on his intensive earlier study of similar cholera outbreaks, not an induction arrived at primarily from the geographical facts of the case. While Snow was clearly thinking in topographical terms (visualizing the location of houses where deaths occurred in relation to the placement of pumps), in the case that he presented to the parish officials he neither said nor alluded to the idea that a map had been instrumental in the discovery of the source of the outbreak.

Snow first exhibited a cholera spot map (see below) (with small black bars indicating deaths) of the Broad Street area at a meeting of the Epidemiological Society of London on Dec 4, 1854, nearly 3 months after his first investigation. He had in the interim made two more local inquiries in the Broad Street area, though one was hampered by the large number of local residents who had fled the region. By December, Snow had gathered data on 616 deaths, but because he did not know the exact address of some residents of St James’s parish who had died outside the district, his map had only 574 bars.

Snow may have realized that a spot map would be a useful illustration for his report to the parish committee and for his own book. The first edition of On the mode of communication of cholera, published in 1849, contained no maps and only one table.  By 1854 Snow had seen the excellent map in Shapter’s work on the cholera in Exeter, which Shapter included as a frontispiece but hardly discussed in his text.  Shapter’s book, which Snow cited in the second edition of his own work, may have persuaded Snow of the value of a map as an illustration.

Snow published two slightly different versions of his map, of which the map published in his cholera monograph appears to be the earlier. By the time the parish report was published 6 months later, Snow had made a few revisions. The most important was the addition of a dotted line enclosing the area that was closer to the Broad Street pump (in walking distance) than to any other street pump (see below). Such an equidistance line dividing a map into regions is called a Voronoi diagram, and Snow’s second map has been credited with being the earliest use of this device. The map with the Voronoi diagram most closely mirrors Snow’s narrative account of his investigation on the spot; and the text of his report to the parish committee is altered from the version that appeared in the monograph to refer to this new feature of the map.  This variation between Snow’s two maps lends further support to the hypothesis that he compiled them for illustrative rather than investigative purposes.  As a result of his two later investigations on the spot, Snow had amassed even more data to show that most people who died of cholera, but who lived outside the Voronoi area, had nonetheless drunk water from the Broad Street pump.

Besides the Voronoi diagram, Snow made an apparently small change that later proved important. In his first map, Snow had located the Broad Street pump in the wrong place, in front of the Newcastle Arms, the public house on the corner (still there in what is now Broadwick Street but today named after John Snow) rather than adjacent to the house next door at number 40. If Snow ever saw the more accurate government maps that we will describe below, he would have discovered that the spot at which he showed the pump was actually occupied by a sewer grating. When he revised his map, he moved the pump 24 feet to the west, to its correct location.

Snow also modified the map in the parish report in several minor ways. He altered the political boundary lines to better show the area within which deaths had occurred, and added subdistrict division lines. He included one distant pump that had not been shown on his first map, raising the total number of pumps depicted from 13 to 14. He missed a more distant pump, in Nag’s Head Yard, that was shown on the other maps we will discuss below.

Because Snow was preoccupied with his more important south London study, his initial investigation in Broad Street was brief. Another member of the parish inquiry committee, Rev Henry Whitehead, eventually discovered the probable cause of the contamination in the water of the pump. In April, 1855, Whitehead learned that a child at 40 Broad Street had become ill with “diarrhea” at the end of August, and died on Sept 2. Her mother had washed the soiled nappies and disposed of the water through the house drains — drains that were later shown to run a few feet from the well of the pump. An earlier excavation of the Broad Street pump well, in the autumn of 1854, had found the brick lining apparently intact. But, in late April, 1855, a more careful excavation showed that both the house drain and the pump well had decayed brickwork that permitted percolation of fluid from the former to the latter. Snow, unaware of the death of this child, drew only four bars at number 40. Later maps incorporated Whitehead’s data and showed five bars.

MSU Snows Map

(Above) Snow’s spot map of the Golden Square outbreak, 1854.

MSU Snows Spot Map

(Above) Detail from Snow’s spot map of the Golden Square outbreak showing area enclosed within the Voronoi network diagram. Snow’s original dotted line to denote equidistance between the Broad Street pump and the nearest alternative pump for procuring water has been replaced by a solid line for legibility. Fold lines and tear in original (adapted from CIC, between 106 and 07).

Snow's Spot Map - Detail

(Above left) Snow’s spot map, detail of area around the Broad Street pump (from  MCC2). (Above right) Snow’s spot map, detail of area around the Broad Street pump. The finely dotted Voronoi line is in the lower half; the symbol for the Broad Street pump-circle around black dot-has been repositioned to its correct location opposite no. 40 Broad Street (from CIC, between 106 and 107).

The Later “Government” Maps

The Committee on Scientific Inquiries of the General Board of Health, the national body charged with investigating the cholera epidemic, also supervised the drawing of a spot map of the Broad Street area. This was printed both in the St James’s parish report and in the more voluminous central government report. The precise relation between this map and Cooper’s earlier map is unknown; the Parish report refers to their map as “constructed on the authority of the one published in Mr Cooper’s Report”, but it is unclear whether this refers to the map as a whole, or only to the diagram of the sewers.

The later government maps were (like Cooper’s map) more detailed than Snow’s. For example, clusters of bars depicting many deaths in the same house were better drawn, compared with Snow’s map where some of the bars appeared to be at quite a distance from the actual location of the house. The houses were numbered, making comparisons between the map and other data easier. The government investigators also had the advantage of Whitehead’s discovery of the “index case” of the infant at number 40, Broad Street — that house shows five bars on the government map (see below), compared with four bars on Snow’s two maps (see above).

But having a better map to work from assured neither adoption of Snow’s theory nor agreement among those who studied the map. The parish committee, as we have seen, supported Snow’s claim that the Broad Street pump was the source of contamination, even though they held back from endorsing Snow’s entire theory of the pathophysiology of cholera. By publishing the government map, they thought they were providing additional evidence in Snow’s favor. By contrast, the Committee on Scientific Inquiries of the General Board of Health flatly rejected the pump theory and insisted that some concentrated noxious atmospheric influence, no doubt emanating from putrefying organic matter, was the cause of the Golden Square outbreak. The committee’s thinking paralleled that of another highly respected cholera authority, Edmund A Parkes:

“On examining map given by Dr Snow, it would clearly appear that the center of the outburst was a spot in Broad-street, close to which is the accused pump; and that cases were scattered all round this nearly in a circle, becoming less numerous as the exterior of the circle is approached. This certainly looks more like the effect of an atmospheric cause than any other; if it were owing to the water, why should not the cholera have prevailed equally everywhere where the water was drunk? Dr Snow anticipates this by supposing that those nearest the pump made most use of it; but persons who lived at a greater distance, though they came farther for the water, would still take as much of it … There are, indeed, so many pumps in this district, that wherever the outbreak had taken place, it would most probably have had one pump or another in its vicinity.”

It was not unusual at that time to see spot maps invoked in defense of a miasmatist theory of disease transmission. As early as 1798, Seaman used two spot maps to illustrate a report on deaths from yellow fever in New York [16], and these maps were later used by both contagionists and anti-contagionists to advance their respective causes.

Cooper marked with a thick bar each house in which death from cholera had occurred, and indicated only by thin lines how many deaths had occurred in each house. Thus households that had suffered one and ten deaths, respectively, appeared similar on quick inspection. For Cooper, the cause of cholera was obviously a generalized environmental influence, and so what mattered were the locations at which deaths had occurred. By contrast, Snow’s theory required the unit of analysis to be the individual, since in any house, some might have drunk the pump water and some not. Nonetheless, the Board of Health adopted Snow’s method of marking the frequency of individual deaths (which was the standard method of the day), but without accepting Snow’s theory.

The different conclusions drawn by the two official investigations in Broad Street are reflected in the one change that the parish committee made in the government map. The Board of Health, in constructing their map, saw no reason to focus on the Broad Street pump. By contrast, on the otherwise identical map included in the parish report, a circle was drawn, of a radius of 210 yards, with the Broad Street pump at the center. This circle defined the “cholera area”, within which the mortality was greatest. The parish committee apparently did not realize that by depicting the high-risk zone as circular, they were inviting a rebuttal such as Parkes’, that the diffusion of an impure atmospheric influence would best explain the distribution of deaths. By contrast, Snow in drawing his irregularly-shaped area based on walking distance to the nearest pump, neatly turned aside such a criticism.

The government map-makers disagreed among themselves in one other way. The local inspectors appointed by the General Board of Health to investigate the Broad Street outbreak, Drs Fraser, Ludlow, and Hughes, found themselves walking the pavements at the same time that Cooper was making his survey of the sewers, and the two groups exchanged information on at least one occasion. But, while Cooper thought that his own map conclusively proved that the sewers were not to blame for the epidemic, the Board inspectors stated in their report that the gully-holes and their bad smells had been a major source of the cholera.  Neither Cooper nor the Board inspectors offered any sort of numerical analysis in defense of their respective interpretations.

MSU Whitehead Map

(Above) The General Board of Health map used by CIC, with Whitehead’s “cholera area” indicated by a circle (CIC, between 96 and 97).


It appears that John Snow thought geographically, but did not use a map to discover the likely source of the Broad Street outbreak. Snow’s map of the epidemic area was simply the visual representation of a deduction from a theory of transmission developed earlier, which in turn was grounded in a theory of the pathology of cholera as primarily a disorder of the gastrointestinal tract. But, since 1902, when reproductions of his maps began to appear in textbooks of hygiene and public health, our fascination with the map has tended to distort our understanding of his methods. As our survey of the government Broad Street maps has shown, the mere act of seeing data arranged graphically in space yields no new understanding without the support of a pathological theory.

One sees an echo of Snow the mapmaker, without the corresponding appreciation of Snow the thinker, in today’s “desktop mapping revolution” among public-health investigators, both lay and professional. Geographic information systems (GIS) are in vogue to show the geographical distribution of individual or aggregate morbidity or mortality. GIS and spatioanalytical research in general has great potential when used to test specific biologically plausible hypotheses about causes of disease. But these same methods can be dangerously misleading when used merely to generate information about geographical and epidemiological associations. Associative data, plotted in the form of a highly sophisticated and accurate map, may easily seduce us into concluding that we have learned something about the cause of disease. Resulting claims about disease “hot spots” may create unjustified worry and distract attention from solid but less visually appealing lines of research. If the methodological assumptions underlying these uses of GIS are correct, Edmund Cooper and not John Snow would have been credited with unraveling the Broad Street cholera outbreak.

As the tale of the Broad Street pump has been transformed into an anecdote resembling an urban legend, a recurring theme represents Snow as a clear-eyed modern thinker who saw the facts, and was opposed by defenders of ancient preconceived theories. But it misrepresents history, and does Snow an injustice, to imagine that he was not guided every bit as much by his own theory as his opponents were by theirs.

DataViz History: The Ghost Map: Building a Case and The Pump Handle

pump2Dr. John Snow is credited with taking bold action when he sensed that contaminated water from the public pump on Broad Street was the cause of deadly cholera during the 1854 outbreak in London. Here is what he wrote of his legendary action on September 7, 1854. [SOURCE]


“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.”

– John Snow in his 1855 book

So who was the parish Board of Guardians and why did they respond as they did to Dr. Snow’s recommendation?


In England, the parish is the fundamental tier of local government. Saint James’s parish encompassed the region serviced by the Broad Street pump. The Board of Guardians was elected by local citizens, but only those who owned property, thereby excluding many ordinary people. The voters were usually small tradesmen or shopkeepers who were concerned with public safety and order. The Board of Guardians was responsible, among other concerns, for maintaining public health, but relied on the advice of medical practitioners such as Dr. Snow.

There were several views of what happened on September 7, 1854 when Dr. John Snow spoke to the Board of Guardians at the Vestry Hall near his home and the impact thereafter on the Broad Street outbreak.


Snow’s good friend, Dr. Benjamin Richardson, wrote years later in 1858 of the September 7th meeting.

“When the Vestry (the term used for a committee of members elected to administer the temporal affairs of a parish) men were in solemn deliberation they were called to consider a new suggestion. A stranger had asked in a modest speech for a brief hearing. Dr. Snow, the stranger, was admitted, and in a few words explained his view of the ‘head and front of the offending’. He had fixed his attention on the Broad Street pump as the source and center of the calamity. He advised the removal of the pump handle as the grand prescription. The Vestry was incredulous but had the good sense to carry out the advice. The pump handle was removed and the plague was stayed. There arose, hereupon, much discussion among the learned… but it matters little for the plague was stayed.”


lankester1862In 1866, twelve years after the event, Dr. Edwin Lankester wrote further of the pump handle incident. He was a member of a local group that looked into the causes of the Broad Street outbreak, and was later to become the first medical officer of health for the St. James’s district (the area where the outbreak occurred.

“The Board of Guardians met to consult as to what ought to be done. Of that meeting, the late Dr. Snow demanded an audience. He was admitted and gave it as his opinion that the pump in Broad Street, and that pump alone, was the cause of all the pestilence. He was not believed — not a member of his own profession, not an individual in the parish believed that Snow was right. But the pump was closed nevertheless and the plague was stayed.”


At the time of the Broad Street pump outbreak, Reverend Henry Whitehead was a 29-year-old cleric at a church in the Broad Street area. He became interested in the epidemic and conducted his own investigation, independent of Dr. Snow.

The Index Case?

mother_infantRev. Whitehead may have discovered the origin of the Broad Street pump outbreak, which started on August 30, 1854. An infant girl at 40 Broad Street near the pump had an attack of diarrhea on August 28-29 that lead to her death on September 2nd. The mother described to Rev. Whitehead how, during her baby’s illness, she had steeped its soiled napkins in pails of water and had emptied some of these into the cesspool at the front of the house. Whitehead was struck by the dangerous proximity of the cesspool to the pump well and convinced a government engineer to examine the area. This examination revealed the seepage of fecal matter through the decayed brickwork of the 40broadstreet_smallcesspool to the well which was less than three feet away. If the child had died of cholera (which Whitehead supposed), then this likely would have been the index case that started the Broad Street pump outbreak.

For more on the index case at 40 Broad Street, click here.

Reverend Whitehead’s views on the effects of the Board of Guardians removing the pump handle were presented in 1867, thirteen years after the outbreak had occurred.

“It is commonly supposed and sometimes asserted even at meetings of Medical Societies that the Broad Street outbreak of cholera in 1854 was arrested in mid-career by the closing of the pump in that street. That this is a mistake is sufficiently shown by the following table which, though incomplete, proves that the outbreak had already reached its climax, and had been steadily on the decline for several days before the pump-handle was removed.”

The table he presented showed how the number of fatal cholera attacks had diminished from 142 on September 1st, to 14 on September 8th, the day on which the pump was closed. Thereafter the new fatal cholera cases fell to single figures and slowly dwindled away.

Whitehead went on in his presentation.

“I must not omit to mention that if the removal of the pump-handle had nothing to do with checking the outbreak which had already run its course, it had probably everything to do with preventing a new outbreak, for the father of the infant, who slept in the same kitchen, was attacked with cholera on the very day (September 8th) on which the pump-handle was removed. There can be no doubt that his discharges found their way into the cesspool and thence to the well. But, thanks to Dr. Snow, the handle was then gone.”


A month after the September 8th removal of the pump handle, Dr. Snow spoke of his views on cholera before the Medical Society of London on October 14, 1854. An account of his talk appeared in the October 21st issue of the The Lancet.


Was his action important, based on sound logic and understanding of the local situation? Or did John Snow and the Board of Guardians over-react?

Contemporary epidemiologists view removing the pump handle as appropriate, and honor Snow’s action to safeguard the public, even in the face of biological and epidemiological uncertainty.

Next: Myth-Making and Evolution of the Ghost Map


Brody H et al. The Pharos 62(1), 2-8, 1999.

Chave, SPW. Medical History 11(2), 92-109, 1958.

English MP. Victorian Values — The Live and Times of Dr. Edwin Lankester, 1990.

Rivett, G. The Development of the London Hospital System, 1986.

The Lancet 67, 339-41, 1854.

DataViz History: The Ghost Map: Index Case at 40 Broad Street

40broadstreet_smallDid the index (or first) case of the Broad Street Pump outbreak live at 40 Broad Street, close to the pump? Reverend Henry Whitehead thought so after a detailed investigation of cholera cases in 1854 following the outbreak. [SOURCE]

The woman living at 40 Broad Street (Sarah Lewis, wife of police constable Thomas Lewis) lost both her five-month old child, Frances, and husband to cholera. In the four to five-day interval between her child’s onset of diarrhea on August 28-29, 1854 and subsequent death on September 2, 1854, Mrs. Lewis had soaked the diarrhea-soiled diapers in pails of water. Thereafter she emptied the pails in the cesspool opening in front of her house.

Likely baby Lewis had Vibrio cholerae which contaminated the napkin used to absorb diarrhea. Reverend Whitehead conveyed his suspicion concerning the possible index case to the Medical Committee of the Board of Guardians responsible for the public health of the area. The Board sent a surveyor to assess the situation. He created a diagram of the home and cesspool and reported that decayed brickwork in the cesspool resulted in seepage of fecal debris to the Broad Street pump which was about three feet away (see picture).

house40aThe death certificate for baby Frances was filled out by Dr. William Rogers, a local physician. doctor who had attended baby Frances at 40 Broad Street opined in a detailed letter to Reverend Whitehead that the cause of death was acute diarrhea, not cholera, an opinion that he repeated at a meeting of the London Epidemiological Society. Since Vibrio cholerae was not discovered until 1884, it is doubtful that Dr. Rogers could have accurately distinguished by signs and symptoms alone non-cholera acute diarrhea and cholera diarrhea. Thus Whitehead’s theory is certainly plausible that the infant at 40 Broad Street was the index case.

Thomas Lewis, the baby’s father, came down with a fatal attack of cholera on September 8, 1854, the same day that the Board of Guardians had the Broad Street pump handle removed. Assuming wife Sarah Lewis poured water from his soiled garments into the household cesspool, it is likely that water of the Broad Street pump would have remain a source of further infection, if the handle had not been removed.


Why was the cesspool at 40 Broad Street not maintained? Such neglect was increasingly common in London, due in part to economic circumstances. At the time of the Broad Street pump outbreak, London had about two hundred thousand cesspools. For many years, the contents of the cesspools were sold as agricultural manure to be used as fertilizer in the many farms that surrounded London. The money earned from manure sales would then be used to maintain the cesspools. Yet during the nineteenth century as London’s population grew ever more rapidly, farms were forced to move further from the central city. Transportation costs increased, adding to the expense of acquiring cesspool-based manure. Starting in 1847, another change took place that undercut the sale of cesspool manure. Solidified bird droppings (or guano) were brought in as fertilizer from South America at a price far below cesspool manure.

With no economic incentive to sell their feces, poor people would empty human wastes into the streets, or directly into the London waterways. Most lacked public health understanding of how disease was spread, as did many medical and health officials of the times. In the absence of manure sales, cesspools became expensive to clean. As a result, they were poorly maintained and infrequently emptied. Over time this neglect lead to cracks and crevices, which offered opportunities for the spread of enteric pathogens. Such spread of Vibrio cholerae probably occurred at 40 Broad Street.

Given the diarrhea symptoms of the young infant and the assessment of the cesspool by the surveyor, Reverend Whitehead likely determined the index case that started the infamous Broad Street pump outbreak.


Boylan, D. Personal Communication, 2009.

Brody H et al. The Pharos 62(1), 2-8, 1999.

Chave, SPW. Medical History 11(2), 92-109, 1958.

Halliday, S. The Great Stink of London: Sir Joseph Bazalgette and the Cleansing of the Victorian Metropolis, 1999.

Paneth N. et al. American Journal of Public Health 88(10), 1545-1553, October 1998.

Vinten-Johansen, P et al. Cholera, Chloroform, and the Science of Medicine. A life of John Snow, 2003.

How To Take a Steam Bath: Victorian Visual Health Guides

The history of health is peppered with gorgeous anatomical flap-ups, strange medical art, and vibrant vintage illustrations, with a side of beautifully illustrated pseudoscience. But few come close to these vintage gems from the early 1900s, found in a French edition of Friedrich Eduard Bilz’s 1888 naturopathic medicine guide Das Neue Naturheilverfahren (The New Natural Healing (public library). Charmingly illustrated in the familiar style of early twentieth-century medical art, they offer visual directions to various methods of curing disease, from steam baths to massage to swimming. [SOURCE]







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