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. 2011 Jan 4;5(1):e925.
doi: 10.1371/journal.pntd.0000925.

Ecology and geography of plague transmission areas in northeastern Brazil

John Giles  1 , A Townsend Peterson, Alzira Almeida
Affiliations

Ecology and geography of plague transmission areas in northeastern Brazil

John Giles et al. PLoS Negl Trop Dis. .

Abstract

Plague in Brazil is poorly known and now rarely seen, so studies of its ecology are difficult. We used ecological niche models of historical (1966-present) records of human plague cases across northeastern Brazil to assess hypotheses regarding environmental correlates of plague occurrences across the region. Results indicate that the apparently focal distribution of plague in northeastern Brazil is indeed discontinuous, and that the causes of the discontinuity are not necessarily only related to elevation-rather, a diversity of environmental dimensions correlate to presence of plague foci in the region. Perhaps most interesting is that suitable areas for plague show marked seasonal variation in photosynthetic mass, with peaks in April and May, suggesting links to particular land cover types. Next steps in this line of research will require more detailed and specific examination of reservoir ecology and natural history.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Overview of the area of analysis in northeastern Brazil.
Inset shows geographic location. Map shows the five plague foci in the region and known plague occurrences (black dots), each with its respective 50 km and 200 km testing regions (see Methods). Shading indicates elevation, as follows: white  = <200 m, light gray = 200–500 m, medium gray = 500–800 m, and dark gray = >800 m.
Figure 2
Figure 2. Example of model predictions for plague suitability in northeastern Brazil.
The maps show the results of using occurrence data from four plague foci to predict the distribution of cases in the southwest focus, based on climate data and AVHRR NDVI greenness index data, with and without elevation data. 50 km and 200 km testing extents are shown. Shading indicates the number of best-subset models (see Methods) that predict suitability- light gray = any (1–5), pink = most (6–9), and red = all (10).
Figure 3
Figure 3. Visualization of year-round trends in AVHRR NDVI greenness index for plague-suitable and unsuitable areas.
Areas predicted as suitable (i.e., suitability value of 10) versus unsuitable (i.e., suitability value of 0) for plague transmission are contrasted.
Figure 4
Figure 4. Projection of models based on all available occurrence data from northeastern Brazil across eastern Brazil.
The green star represents the approximate location of the Serra dos Orgãos plague focus. Shading indicates the number of best-subset models (see Methods) that predict suitability- light gray = any (1–5), pink = most (6–9), and red = all (10).
See this image and copyright information in PMC

References

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