Meeting Abstract
Environmentally mediated indirect pathogen transmission is explicitly linked to host movement and foraging in areas where pathogens are maintained in the environment. In the case of anthrax, spores of the causative bacterium Bacillus anthracis are released into the environment following host death creating localized infectious zones (LIZs). In grassland anthrax systems, the most likely route of infection in herbivores is ingestion of spores while grazing at LIZs. Here we used camera traps to assess how ungulate species utilize carcass sites in Southwest Montana and evaluated how these behaviors may promote indirect anthrax transmission. Data were collected from August 2016 to September 2018 at 14 carcass sites (proxies for LIZs) and 13 control sites (comparable habitat without LIZ) for a total of 470,221 independent photographs during 12,533 camera trap days. Data analysis is ongoing; however, initial results suggest that adult male bison spend more time grazing at LIZs than calves, yearlings, or adult females. Similarly, adult male elk are more likely to graze at LIZs than control sites. These data are consistent with previous findings in the study area that during anthrax outbreaks adult male bison and adult male elk were disproportionately affected. Further, white-tailed deer (WTD), mule deer, and moose show no preference for LIZs over control sites; anthrax in WTD is rare in the study area and not reported in mule deer or moose. Serological surveys mirror these findings with little B. anthracis exposure in female elk and frequent exposure in males. Our findings suggest that LIZs promote grazing and differentially attract male and female hosts.
