Modeling the Environmental Suitability for Bacillus Anthracis Spores Survival in the Qinghai Lake Basin, China

Abstract

Introduction: Bacillus anthracis spores may remain viable for many years in soil. Previous studies have identified East Qinghai and neighbouring Gansu in northwest China as a potential source of anthrax infection. This study was carried out to identify conditions and areas in the Qinghai lake basin that are environmentally suitable for Bacillus anthracis spore survival. Materials and Methods: Anthrax occurrence data from 2005 – 2016 and environmental variables were spatially modeled by a maximum entropy algorithm to evaluate the contribution of the variables to the distribution of the spore. A Principal Component and Variance Inflation Analysis were adopted to limit the number of environmental variables and minimize multicollinearity. Results: The three variables that contributed most to the suitability model for B. anthracis spores are a relatively high annual mean temperature (53%), soil type (35%), and a high human population density (12%). The most significant soil types were cambisols and kastanozems. The resulting distribution map identifies the permanently inhabited rim of the Qinghai Lake as highly suitable for the survival and persistence of the spores. Conclusion: The highly suitable areas for spores could be considered as a risk zone for Anthrax infection by spores of the livestock and the human population. Our environmental suitability map and the identified variables provides the nature reserve managers and animal health authorities readily available information to devise a surveillance strategy in B. anthracis suitable regions to abate future epidemics.