The Cholera Epidemic of 1855-56

Here is the movement of the first terrible cholera epidemic in Brazil as it spread in 1855 and 1856.  This is the first map of its kind for Brazil and up to now, no one has given us a full picture of where cholera struck and how fast it spread [red indicates confirmed areas of disease presence, red lines indicate sporadic cases, red points are areas where cholera was probably infecting people, but this was not confirmed by the presidential reports]. In the handful of regional studies of this epidemic or references to the disease in Brazilian history, it is easy to get the impression that it infected Brazilians throughout the country during these years. This was not the case, as these illustrations make clear. There were some other discoveries that I will discuss in more detail when I write this chapter: 1) rivers facilitated the spread of cholera; 2) it did not cross mountain ranges; 3) it always struck larger urban population centers on the coast before spreading inward; and 4) the Brazilian North and Northeast were affected much more than the southern and south-central parts of Brazil. One of my goals is to measure the economic consequences of epidemics and disease like cholera, and I have an unproven hunch that the Northeast suffered in economic terms much more from these disasters than other regions.  A set of larger (.pdf) maps are available here.

Update on Saturday, November 29, 2008 at 8:06AM by Ian Read

A friend of mine, who studies the colonial history of the Amazon, asked me how it was possible that large areas of largely uninhabited and forested lands could have had cholera infections.  She pointed out that diseases followed the river routes during the colonial period and so this seemed very plausible for the cholera epidemic.  But when we look closely at Pará or Amazonas, riverine infections are not well represented.  This is a good point and it speaks to the limits of our historical sources.  The main source of information for these maps were the sections on public health and epidemics in the Provincial Presidential Reports.  The presidents often gave rich information, but usually limited their discussion to the level of the comarca.  A comarca was one jurisdictional level above a municipio ("county" or "township") and one below the province.  There were between four and 20 comarcas in each province and they usually included large areas of rural and sometimes unpopulated land.  When a president reported that there was cholera is a certain comarca, it is usually impossible to know what places within that jurisdictional area had the most or least cases.  Often, the presidents themselves had little idea.  Other presidents had better information.  For example in Pará and Alagoas, I have information on the municipal level that I plan to represent cartographically.  While the maps above tell a great story at the national level, I will focus on one or two provinces to give a history of how cholera spread at a provincial level.