yellowfever

The Yellow Fever Epidemic of New Orleans, 1878

The yellow fever epidemic of 1878 is one of the most geographically interesting contagions in United States history. The epidemic was thoroughly documented in New Orleans by the Board of Health for Louisiana, with both written description and mortality roles including victim’s residence. These data were used to create a GIS of the epidemic to investigate the spatial structure and diffusion of the disease. This paper presents a spatial overview of the epidemic, with a concentration on the entry point of the disease, before considering two specific questions. One, was the steamboat Emily B Souder the culprit vessel that first brought the disease into the city, as described in contemporary accounts such as the 1878 Louisiana Board of Health Report? Although the steamboat fits the pattern of the likely entry of the disease into the city, it cannot be conclusively stated this was the origin. Second, yellow fever is transmitted by Aedes aegypti, an urban mosquito species with limited dispersal, which has been the confirmed vector in other recent epidemiological studies. Knowing this, did individual residences play an integral role in the spatial structure of the epidemic? Two epidemiological models were constructed within the GIS, the Gi* which has previously been used for mosquito-borne diseases, and a Basic Reproduction Number (BRN) algorithm were used to test this second question. Both models found elevated cluster levels for single buildings. The highest BRN value, which connected the number of sicknesses attributed to a first case introduction, was estimated at 195.

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The location of the hypothesized first two cases of yellow fever in the city and the location of port for the Emily B. Souder.

The mortality pyramid for the 1878 epidemic.

The locations of individual index cases identified by the BRN algorithm. Red symbols indicate locations of index cases identified using the most conservative rule set, while yellow symbols indicate index cases identified using a relaxed criteria.

Click the image (above) to watch a day-by-day Cartographic Animation of the dispersion of 1878 yellow fever epidemic across the city of New Orleans.

Animation credits: Andrew Curtis, Tim Joyner, Jason Blackburn, John Anderson

Current research is focused on the application of the G statistic to investigate the geographic scale of yellow fever hotspots throughout the city during the epidemic and the development of a Spatial R₀.