The ecological niche of reported rabies cases in Canada is similar to Alaska

Abstract

The ecology of rabies in the circumpolar North is still not well understood. We use machine learning, a geographic information system and data explicit in time and space obtained for reported rabies cases and predictors in Canada to develop an ecological niche model for the distribution of reported rabies cases in the American north (Alaska and Canada). The ecological niche model based on reported rabies cases in Canada predicted reported rabies cases in Alaska, suggesting a rather robust inference and even similar drivers on a continental scale. As found in Alaska, proximity to human infrastructure-specifically along the coast-was a strong predictor in the detection of rabies cases in Canada. Also, this finding highlights the need for a more systematic landscape sampling for rabies infection model predictions to better understand and tackle the ecology of this important zoonotic disease on a landscape scale at some distance from human infrastructure in wilderness areas.

Keywords: Alaska; Canada; Machine Learning; Rabies; geographic information system.

FIGURE 1

Distribution of reported rabies cases in Canada 2007–2016 included in subsequent data mining and machine learning modelling

FIGURE 2

Predicted relative index of occurrence (RIO) of reported rabies for Canada and Alaska based on reported rabies cases in Canada. Red indicates high RIO, green indicates low RIO

FIGURE 3

Relative index of occurrence (RIO) of reported rabies cases as a function of human population density in the model output from model based on reported rabies cases in Canada. RIO is related to human populations although heavily biased sampling for possible human exposure has to be considered when interpreting this association

FIGURE 4

Relative index of occurrence as a function of distance to coast in the model output from model based on reported rabies cases in Canada. The data show that reported cases are distributed in a biphasic distribution in relation to distance to coast

FIGURE 5

Overlay of ecological niche model, based on Canadian cases, onto Alaska. Grey area indicates +0.025 relative index of occurrence (RIO) from Figure 2 for binary display purposes. Blue dots indicate reported rabies cases (Huettmann et al., 2017)