A Survey has been developed to document and compare GIS utilization in the workplace. This survey assesses GIS availability and utilization in both academic and non-academic work settings. The purpose is to document the need for GIS experience as an occupational skill. GIS is currently being underutilized by most companies. Spatial Technician and Analyst activities and a few managerial activities requiring GIS knowledge or background are reviewed.
This survey, which takes about 20-25 mins to complete (’tis a bit long), can be accessed at
Feb 2013 NEWS!!!
International Journal of Epidemiology has scheduled for publication in their March 2013 issue my review of Lea’s map and its place in medical geography and epidemiological history.
John Lea’s Geological Theory for Cholera
John Lea, Esq. of Cincinnati. 1850. Art. III.–Cholera-the Geological theory. Western Lancet (Cincinnati, Ohio), vol. 12, pp. 89- 97
John Lea, Esq. of Cincinnati. 1850. Art. III.–Cholera-Mistakes Corrected–the Geological theory. Western Lancet (Cincinnati, Ohio), vol. 12, pp. 217-221.
John Lea published his pamphlet with this map in April 1850. Over the next few months it stirred up quite a controversy. By 1851, his map made popular his revival of an old theory for cholera, which he stated as follows:
“It will be found that all those extensive regions of primary and arenaceous formations, where no calcaro-magnesian water is used, have again escaped the much dreaded epidemic, as they did heretofore; and that no well attested fatal case occurred among those who used rain water exclusively; and I may add boiled water, though it is of less purity than rain water, and therefore not so entirely to be relied on when taken alone”
One of the common beliefs about disease during the first half of the nineteenth century was that there was a chemical reason for some of these forms of “miasma” or “contagion”. The suspected cause for many of the ailments for the time, in particular dysentery and several diarrhea cases, had something to do with the chemistry of the ground. This was noted as a geological line of reasoning by most medical writers for the time. Focused on medical topography, many came to be known as medical geologists once strata layering, age, and chemistry became a part of the scientific argument for their ability to cause the various diseases. Others like the followers of Max von Pettenkoffer would argue that it was the soil itself that was responsible for epidemics, which contributed not only due to its chemistry, but also due to its behavior when exposed to water and its ability to expand and contract, flushing out contaminated gases or air masses locked within the more sponge-like strata.
Both geologists and pedologists shared chemistry a common feature of their philosophy for the development of the disease-causing gases. The cause for these gases could easily be argued as the carbonate content of the soils and/or rock formations. These arguments focused on the alkaline make up of these rockforms and the soils they helped to generate. This alkaline nature in combination with a high degree of solubility of the rock or soil articulates in water demonstrate reasons, at least within the lab setting, as to how certain combined geologic and topographic settings could be significant in determining whether or not disease-causing gases would be produced and expelled. Thus the ongoing debate about what specifically was the definition for “miasma” or contagion at the medical geographical level. Further supporting some parts of these arguments was the come common nature of gases produced from specific rock formations and minerals. The ability to produce carbon dioxide gases was a finding very supporting of the argument that ‘miasma’ and ‘contagion’ was very much against the life-sustaining principle, or vital force, a concept still popular at the time of these initial observations and related lines of reasoning.
Old Gases or Alkalinity?
It is not unusual to find different lines of reasoning for the same conclusion published within the various medical articles on this medical geography topic. The earliest of these articles in United States published journals appear some time around 1800; as the chemical understanding of rock formations became better understood, so too did the related medical geology disease theories which resulted. Most of these theories for ‘miasma’ or ‘contagion’ focused on the idea that calcium-rich rock formations consisting of limestone, montmorillonite and the like had the ability to produce this disease-causing ”miasma”, which simply remained imbedded within the earth and soil between packed layers, and/or were occasionally released en masse resulting in epidemics or endemics depending on their regularity in relation to local seasonal changes and temperatures. Just how this miasma could be responsible for disease was still a matter of dispute amongst physicians. For many, the simple production of carbon dioxide gas alone, a form of effluvium, did not suffice as an explanation. A more enticing theory receiving much support at the time was the notion that this gas emission aided in the dispersal of other miasmatic gases or effluvia as well, something already embedded within the soil, gases which were more noxious in nature due to their associations with swamps, rotting plant debris, and even food remains and partially buried dead animal materials. With time, this meant that as the ability for the soil to hold gases became better defined, so too did Pettenkoffer’s theory for disease. It took these scientists about 15 years to realize and propose that these older gases harbored within soil could be forced outward from the soil due to the soil’s own physical behaviors related to water availability and content, i.e. when certain soils swell due to absorbing water they can squeeze out these gases normally resting between soil particulates, thereby exposing locals to this natural source of contagion.
The alternative theory at this time was that the alkaline nature of particular soil types made them more conducive to producing the chemical requirements of diseases trying to develop within a natural environment. Evidence for this take on the soil-borne disease theory was strongly suggested and supported by the behavior of the Asiatic cholera epidemics that struck the United States in 1832, followed by 1849-1852. The association of Asiatic cholera with alkaline soils and waters had its strongest followings during the 1849 on epidemics, the time this article with its map was published. To amateur geologists, the appearance of the diarrhea discharges produced by cholera even added to this theory for this particular disease type. Unlike most severe diarrhea epidemics, Asiatic cholera resulted in the production of white, watery, unpacked granular stools. It often became fatal in just 2 or 3 days. This white appearance even led to the theory that this severe form of diarrhea had something to do with the consumption of contaminated rice grains. To the geologist, this whitish stool-like appearance suggested even more that perhaps certain rockforms could be the responsible for the disease.
Applying this philosophy to Lea’s writings, Lea blames the disease in Cincinnati on the relationships of wells to the local river. He writes
“it is worthy of the special attention of those who live on plantations at a distance from that river, where well water is used (usually procured from wells of ten to thirty feet deep), that wells passing through strata of marl, produce unwholesome water; this can perhaps be remedies by going deeper, or shallower, as the case may require, for it has been observed . . . that the people on one farm would be very sickly, while on one adjoining they were quite healthy . . .”
Lea concluded that water contaminated with some form of contagion, found at a specific level within the local soil, referred to as marl, was the cause for this epidemic. The marl Lea refers to is a layer of hardpack or rock layer consisting mostly of lime and calcium carbonate-rich materials. Referred to in some forms as limestone, this rock and its breakdown products can be in multiple forms ranging from chalk cliffs, to white terraces, to fossil-rich shell deposits, to highly exposed, hardpack of crumbly land masses. In modern terms, Lea had successfully determined the chemical needs for the organism responsible for Asiatic cholera, vibrio cholerae. This organism survives better in alkaline waters, which in marl settings would be a consequence of water-filled pockets, holes and air spaces formed within calcium-carbonate rich soil and rock beds due to the solubility of these hardpacks to the ample amounts of water passing alongside and through these layers.
John Snow versus John Lea
John Snow’s first edition on Cholera was published late in 1849, and was a reflection of the the ongoing theory for cholera at the time due to this epidemic’s behavior in England the years before. Snow’s work focused on the condition of a local water supply and the lack of cleanliness that people within heavily population urban settings were suffering. But it did little to satisfy the curiosity of those seeing cholera strike in non-urban settings, people often unable to distinguish the endemic version of cholera or severe diarrhea that often struck over the years, from this new more fatal form of disease that was taking so many lives.
Medical topography in general had helped helped medical topographers formulate their own new hypotheses about water itself as a potential cause for diseases like Asiatic cholera outside the urban settings, where population and sanitation appeared to be less of a problem, or at least a problem with causes atypical or urban locations (i.e. farm and livestock related filth). At first, due to its timing and local origins, Lea’s work received more respect than Snow’s theory due to a seemingly broader applicability for cases of “cholera” within non-urban settings. But it was the lack of sufficient knowledge about the difference between what is today considered true asiatic cholera and the other forms of choleras for the time referred to as choleriac diseases by some, that in general led to this problem in communication of knowledge both inside and outside of the medical profession.
In spite of this public interpretation of the disease and how much the doctors knew, or didn’t know due to its high and unpredictable mortality rates, we can tell that doctors had a better handle on its behavior than commonly thought, as indicated by articles published in the medical journals for this time. Doctors had a much better understanding of its behavior than the public was aware of. This lack of understanding the doctor’s views on this disease is what enabled others, like Lea, who were not physicians as Lea to create and hypothesize with their own hypotheses. Anyone with a broad knowledge base could develop his or her own theory to help to explain all of the the numerous exceptions that arose with their logic. Such behaviors allowed Lea to maintain a following which could convince the community at large about the proof that existed for his speculated causes.
The same was true for other writers as well. There were physicians and non-physicians who had the knowledge base and experience needed to contrive their own hypotheses, most of whom promoted such theories in and out of the press during the early 1850s. The best examples of this are those theories that defined the extraterrestrial causes for cholera like solar cycles, the effects of gravity upon the tides, meteors and comets. Then there were those writers who blamed cholera on the effects of the earth’s crust, terrain and topographic features, ranging from theories that focused just on solar aspects (the angle of the sun on the face of a mountain) and the earth’s magnetic influences and abberancies. Then there were those theories focused on the effects of viruses and animalcules. Viruses were still likened more to chemical substances linked to the term “miasma” than they were to being a kind of living organism; viruses were were very much still theoretical in nature during this time, not at all visible. Their counterparts, the animalcules, offered more substantive proof for this theory, with new ones being discovered and documented on a very regular basis. Then there were those individuals who claimed that the various aspects of natural drainage and percolation behaviors that are defined by soil and rock types could be a cause, precedents of the famous German geographer Max Pettenkoffer, who made claims that gases contained between soil particles could be forced out from the soil below, due to water from rain seeping into these spaces.
Lea’s theory for Asiatic Cholera was applicable to both the non-urban and urban environments. Its focus on rocks, soil and water, not people and their filthy living habits, made it attractive to many. John Snow’s theory and many others being published in the medical journals implied the role of people in the cause for this disease, and the theoretically non-potable water that providers were supplying low income communities with. Lea’s theory could be applied to settings where Snow’s theory could not be true–communities with well water, not company developed water sources. In the midwest and most rural parts of the United States, Lea’s theory prevailed.
Ironically, there had already been the discovery needed of the actual organism responsible for this disease, vibrio cholera. But it would take a few more decades to convince physicians and scientists that such a finding was correct. This discovery had already taken place in Europe, a few years prior to the time that Lea’s and Snow’s articles were published. But the credibility of this discovery of the animalcule was questioned for decades to come, providing both Lea and Snow the chance each needed to refine and further promote their claims. It is not at all unusual for a single discovery and/or technique developed in medicine to take several routes of application, development and analysis before the best of these become the standards for most of the profession. In the long run, Lea and Snow made equally valid and truthful discoveries, but only Snow’s received ongoing international acclaim ever since. It is important to realize that at the times each of these medical geographers made their discoveries, Lea’s findings were more in tradition with the ongoing philosophies and more applicable on a day-to-day, place-to-place basis than Snow’s. It would take Snow’s work another epidemic or two to convince the public that there were some values to his work.
Lea’s hypothesis for disease epidemics demonstrated more support in the years to come in the popular press than Snow’s hypothesis. The reason for this related to the ability of physician to interpret Lea’s findings within his own cholera epidemic settings. Whereas Snow’s findings indicated that something less apparent to scientists could be the cause for the differences in water types related to cholera outbreaks, Lea’s findings suggested that prior beliefs in some miasma, contagion or effluvial cause for cholera remained the cause for these recurring disease patterns. With time, other geologists and topographers found still more natural features that tended to support Lea’s hypothesis. The most commonly cited of these hypotheses was the belief that alluvial fans found along old mountain bases feeding into local streams and the gravel-rich terrains typical of floodplains and river edges were primarily responsible for Asiatic cholera evolution and development. According to medical topographers, these types of topographic settings served as niduses for the eruption of new local outbreaks for which no other human-related or geochemical cause could be attributed.
But evidence for Lea’s failing theory remained common in the popular and professional press for only the next four years, following his first publication of his theory in April 1850, and the publication of the second edition of John Snow’s treatise on cholera.
(More on all of this in my to-be-published article in March/April 2014, International Journal of Epidemiology.)