Land-use as a Factor in the Re-emergence of Rabies Virus in Latin America Open Access

Jones, Christie (Spring 2022)

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Canine vaccination campaigns have substantially reduced rabies cases worldwide. However, in Latin America, dog vaccination has failed to eliminate endemic rabies as the zoonotic virus has persisted in a vampire bat-cattle cycle that appears enhanced by forest conversion for livestock. To improve the understanding of this dynamic, I analyzed spatial autocorrelation of documented bovine rabies outbreaks from 1985 to 2020 (n=109) in Costa Rica. Logistic modeling of known outbreaks with land-use indicators extracted from national spatial data throughout the study period was used to evaluate the impact of anthropogenic activity on rabies incidence. Such analysis showed positive spatial autocorrelation among outbreaks (Moran’s I=0.038, P < 0.05), but no temporal relationship was discovered. Modeling showed an inverse association between elevation and outbreak probability (P < 0.01) and deforestation represented a potential predictor for bovine rabies outbreak (P = 0.05). The effects of land-use on vampire bat (Desmodus rotundus) foraging patterns and diet were also evaluated using stable isotope analyses of tissue samples (n=227) from 12 caves throughout Costa Rica. Principal component analysis (PCA) was used to determine the variance and effect of correlated land-use predictors. Multivariate modeling of PCs revealed significant differences in δ15C between caves and highlighted land-use areas (forest, agriculture, urban), proximities (distance to town, distance to road), and population densities (cattle, human, farm) in the 10km surrounding each cave as significant predictors of vampire bat δ13C values and, consequently, prey preference. PC1 and 2 variables described the intensity and/or proximity of/to agricultural and human development at each cave and were associated with feeding choices of D. rotundus and predicted higher δ13C values, indicating feeding on livestock (GLMM, PC1: Estimate = 0.52, P < 0.001; PC2: Estimate = 0.21, P = 0.38). Overall, these findings demonstrate a connection between human land-use and changing vampire bat ecology, with implications for rabies transmission.

Table of Contents

Introduction 1

Materials and Methods 5

Results 11

Discussion 14

References 18

Figures 21

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