Meeting Abstract
Many organisms experience periods, either seasonally or ontogenetically, of increased vulnerability to disease. We argue here that an unexpectedly large number of emerging epizootics are characterized by an overarching commonality: the host species exhibits complex life histories or life cycles. Among wildlife, examples include White-nose Syndrome (WNS) in bats, sea-star wasting disease (SSWD), coral epizootics, and diverse virulent pathogens afflicting amphibians. For example, WNS is a fungal disease that cycles seasonally in bats, in which hibernation behavior and immunosuppression by the hosts are primary factors determining vulnerability to infection. Similarly, chytridiomycosis and ranavirosis epizootics in amphibians occur around metamorphosis and are exacerbated by ontogenetic shifts in immunity and behavior. These similarities suggest that critical disease windows—periods of increased vulnerability—are shaped by shifts in host susceptibility and exposure to pathogens. Furthermore, environmental change may alter the scale and scope of epizootics in species with complex life histories/cycles by altering windows of disease vulnerability and thus forcing changes in host susceptibility and/or pathogen exposure. Growing evidence suggests that climate change, in particular, can exacerbate many wildlife epizootics through alteration of timing of important events over the life of the host and pathogen. We present a framework to conceptualize these interacting factors. We then explore how this framework may increase our understanding of how environmental change interacts with complex life histories and physiological states to predict epizootic outcomes.
