Phenomena in epidemiology: Exploring the “natural history” of disease

Idea: Detailed observation (like a naturalist) or detective work–albeit informed by theoretical ideas–may be needed before we can characterize what the phenomenon is we are studying, what questions we need to ask, and what categories we need for subsequent data collection and analysis.

1. The initial motivation for this class was to highlight that epidemiology does not necessarily begin with data sets to analyze. There may be exploratory, investigative, detective, anthropological, and naturalist inquiries before phenomena are even noticed, categories are defined, questions are framed. Good examples of this seemed to be provided by John Snow’s work on cholera, Barker’s (1971) research in Uganda, and on “clues from geography” of infant mortality and heart disease (1998), and the three Lancashire towns, and Oxford’s account of the conditions that provided a source for a global pandemic of the 1918 flu. (40 million died from flu, while 8.5m died from war.) Even Barker’s (1999) speculation about anomalous French cardiovascular disease rates looks like someone who is able to connect dots of diverse kinds and that are spread out in time.

2. Brody’s paper, in addition to drawing attention to the role of maps in this exploratory research, makes the Snow story more complicated and interesting. Snow had clear hypotheses that guided his mapping and his advocacy of stopping the water supply from the Broad St pump — he was certainly not simply noticing patterns in the data and hypothesizing about the causes. This account opens up broader questions in philosophy of science. E.g., where do hypotheses that get assessed by research come from in the first place?

(This post continues a series laying out a sequence of basic ideas in thinking like epidemiologists, especially epidemiologists who pay attention to possible social influences on the development and unequal distribution of diseases and behaviors in populations [see first post in series].)


Barker, D. J. P. (1971). “Buruli disease in a district of Uganda.” Journal of Tropical Medicine and Hygiene 74: 260-264.

Barker, D. J. P. (1998). Mothers, Babies, and Health in Later Life. Edinburgh, Churchill Livingstone, pp1-12, 167-172.

Barker, D. J. P. (1999). “Commentary: Intrauterine nutrition may be important.” British Medical Journal 318: 1471-1480. (

Brody, H., M. R. Rip, et al. (2000). “Map-making and myth-making in Broad Street: the London cholera epidemic, 1854.” The Lancet 356: 64-68.

Oxford, J. S., R. Lambkin, et al. (2005). ” A hypothesis: the conjunction of soldiers, gas, pigs, ducks, geese and horses in northern France during the Great War provided the conditions for the emergence of the “Spanish” influenza pandemic of 1918-1919.” Vaccine 23(7): 940-945.

PBS Home Video. (2004). “Killer flu”



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