Fig 1.
Study area and reported snakebite incidence per district, 1990–2007.
Costa Rica is a tropical country in the Central American isthmus. The incidence is shown for the districts where the study species (Bothrops asper) is present. We supposed that in these districts the study species was responsible for all snakebites. Note that highlands and dry northwest plains have no reported incidence of snakebites attributable to this species, whereas the wet lowlands in the central and South Pacific regions have the highest incidence. (Map was produced by using QGIS Geographic Information System, Open Source Geospatial Foundation Project. http://qgis.osgeo.org).
Fig 2.
Study species: Terciopelo pit viper, Bothrops asper.
This species is responsible for most snakebite envenomation throughout its distribution. It is distributed in humid lowlands from southern Mexico to northeastern South America. Photography was taken by Bravo-Vega CA.
Fig 3.
Sampling locations and predicted encounter frequency of Bothrops asper over its distribution.
Each symbol corresponds with a sampling location. Circles are sampling locations in the Pacific versant, while triangles represent locations in the Caribbean versant. Green symbols are lowlands locations (Altitude below 400 m.a.s.l.), brown symbols are midlands locations (Altitude between 400 m.a.s.l and 800 m.a.s.l.), and white symbols are highlands locations (Altitude above 800 m.a.s.l.). Gray areas are places where the environmental niche model predicted absence for the study species. The other map colors show the value of the extrapolated encounter frequency. Encounter frequency was higher in the Pacific versant than in the Caribbean, and it tends to decrease with altitude. Map was produced by using QGIS Geographic Information System, Open Source Geospatial Foundation Project. http://qgis.osgeo.org.
Table 1.
Comparison between different models to estimate snakebite incidence.
Fig 4.
Linear regression for proposed model and reported incidence.
Y-axis corresponds to reported incidence per each district, and x-axis is our estimation of the frequency of encounters with the study species times the rural population for each district. Each point represents the reported incidence and our estimation for each district. The red line indicates the predicted regression, and red shading indicates the 99% confidence interval. The dotted line is the prediction interval. The lineal behavior corresponds with the assumptions of the model, and we found a positive and significant correlation between both variables. Labeled districts are those in which the prediction fell outside of the prediction interval. Figure was produced by using ggplot package in r environment.