SEER Lab PhD student Alassane Barro will defend his doctoral dissertation on 27 April 2016 at 4:30 PM in the Emerging Pathogens Institute. His dissertation is entitled “Integrating geographical information systems and the ecological niche modeling framework to characterize the spatial ecology of anthrax in Australia”. The defense is open to the public and all are invited!
This dissertation explores the spatial ecology of Bacillus anthracis, the causative agent of anthrax, to assess the risk of anthrax disease in Australia. Anthrax is a zoonotic disease that primarily affects herbivores, and incidentally humans and all warmed-blooded mammals. Previous efforts to estimate the spatial extent of the risk of anthrax disease did not consider the role of environmental conditions in the distribution of B. anthracis. Here, the genetic algorithm for rule-set prediction model system (GARP) was used with historical anthrax outbreaks for the period 1996-2013, and environmental data to define the ecological niche of B. anthracis and predict its geographic distribution in the continental Australia. Potential changes in the geographic space of the pathogen were also evaluated using four climate scenarios, the representative concentrative pathways (RCPs), reflecting the environmental conditions by the year 2050. At the local scale, the normalized difference vegetation index (NDVI) data was used as surrogates for climatic variables to investigate potential relationships between climate and anthrax outbreaks. The results of the GARP models revealed that the niche of B. anthracis in Australia is characterized by a narrow range of ecological conditions concentrated in two disjunct corridors: an eastern corridor running from north Victoria to central east Queensland through the center of New South Wales, and a western corridor in southwest Western Australia. Future climate scenarios agreed on a major reduction of the geographic space of B. anthracis in Western Australia and Queensland, and lower latitudinal southeastward shifts. The results of the NDVI-anthrax seasonality study suggest that higher mortality are associated with early summer green-up following prolonged hot and dry spring periods. Collectively, this work contributes to a better understanding of the spatial ecology of B. anthracis and anthrax disease on the landscape of Australia, and provides quantitative tools indispensable for developing intelligent anthrax surveillance programs.