Hemorrhagic Disease in Montana’s Wild Ruminants

Abstract

Epizootic hemorrhagic disease and bluetongue virus have been documented in Montana for decades.  Montana has experienced localized and variable population declines in wild cervids when these outbreaks occur.  Transmission is seasonal in North America, with infection occurring in the late summer and fall.  In northern states, transmission ends once adult vectors cease activity with the onset of winter.  Montana is in an epidemic zone where outbreaks appear periodically and mortality events can be significant.  Montana Fish, Wildlife and Parks wildlife health lab has tested samples from suspected outbreak events, research captures and opportunistically for detection of EHD and BTV.  Environmental factors and virus-vector-host interactions are knowledge gaps that need to be addressed to improve our understanding of these orbivirus dynamics.  Enhanced reporting, surveillance, and research efforts are potential tools that may improve our understanding of the role these viruses play in wild ruminant populations across the state.