On the transmission of anthrax disease in the Arctic region

Recent cases of anthrax disease have severely affected reindeer herds in Siberia. Experts believe that these outbreaks have been caused by the presence of infected carcasses emerged from the thawing permafrost, underlying therefore the emerging character of such disease in the Arctic region due to climate change. Anthrax occurs in nature as a global zoonotic and epizootic disease caused by the sporulating bacterium Bacillus anthracis. It principally affects herbivores and causes high animal mortality. Its transmission occurs mainly via environmental contamination through spores which can remain viable in permafrost for more than 100 years. We propose and analyze a novel epidemiological model for anthrax transmission that is specifically tailored for the Arctic region. In particular, the model investigates the transmission of disease between susceptible and infected animals in the presence of environmental contamination, including also herding practices (e.g. seasonal grazing) and a seasonal environmental forcing caused by the thawing permafrost. We show how the temporal variability of these factors influences the transmission of anthrax disease and how pathogen invasion may be favored as the endemic state of the infection changes. On the basis of our results, further analyses, which may also include spatial dynamics, can establish optimal procedures to prevent uncontrolled diffusion of anthrax infection in herding areas in the Arctic