From the turn of the 19th century, social cartography was centred on mapping contagious disease – the most urgent problem of rapidly growing cities around the world. The examples which feature in my forthcoming book, Mapping Society range from Yellow Fever in New York, 1798, followed by a large number of maps of cholera, ranging across France, Germany and the United Kingdom. Before the creation of epidemiology as a science in its own right, it was the combined efforts of physicians and medical officers (namely public health officials, many of whom themselves had medical training) that contributed the effort of understanding the spatial distribution of disease.
In the UK, it was John Snow who famously hypothesised in the 1850s that cholera was caused by a germ spread through contaminated water, in contrast with the prevalent miasma theory of contagion through bad air (though evidently there were scientists in Italy and Germany working on isolating the bacterium several years previously). The two theories were debated vigorously, but Snow’s ground-breaking studies of the 1853–5 epidemic resulted in his being considered the father of epidemiology, due not only to his well-reasoned statistics but to his maps, which illustrated to a lay audience the evidence of a cluster of cholera cases amongst people living close to a single water pump on Broad Street and, hence, that contaminated water was the source of the disease.
Nevertheless, both in Europe and much farther afield in New Zealand, the evidence for cholera and typhoid being water-borne continued to be debated, with the Wellington medical officer William Chapple’s mapping the incidence of typhoid across the city, to see if he could find where blocked pipes were causing sewer vapours to back up into houses (see image below[i]).
Chapple’s map identifies a cluster of typhoid cases in the Holland Street area of the city, where he had found that the street’s sewer was leaking had contaminated the surrounding soil. Coupled to empirical fieldwork, which found overcrowded housing in the street, the maps were able to highlight (with graphic emphasis of the leaking sewer), the spatial association between housing quality, urban situation and disease.
While the map is quite late for the sequence of disease maps reported in Mapping Society, Ben Schrader has pointed out that the ‘miasma theory’ that disease such as cholera or typhoid were air borne, continued to persist in the country, despite the discovery in 1885 of Salmonella typhi by a US veterinary pathologist Daniel Elmer Salmon[ii] (almost simultaneously with the discovery in 1884 of the cholera bacillus, Vibrio cholerae by the German scientist, Robert Koch.)
Although the fact that the disease was likely to have been the result of contamination of drinking water by leaking cesspits was not yet accepted at this stage, the subsequent construction of municipal water and sewer schemes seems to have had the desired result of a drop in mortality from water-borne diseases in urban New Zealand by the turn of the 20th century.
[i] I am grateful to Matthew Plummer, who brought the map to my attention via Twitter. A downloadable version of the map can be found here: https://teara.govt.nz/en/zoomify/24425/typhoid-map-wellington
The featured image is of a butcher’s shop in Wellington, New Zealand, from: https://teara.govt.nz/en/photograph/23024/19th-century-butchers-shop.