2011-2012 Elk Brucellosis Survey and Research Summary

In the winter of 2011-2012 Montana Fish, Wildlife and Parks initiated the second year of a multiyear project with the goals of delineating the geographical distribution of brucellosis in elk populations, enhancing our understanding of how brucellosis functions in elk populations and providing wildlife managers with information to inform elk management where brucellosis is present. Ninety-three adult female elk were captured in hunting district (HD) 325, and 30 adult female elk were captured in HD 329. Elk were initially tested for brucellosis in the field and again at the Montana Dept. of Livestock Diagnostic Laboratory at a later date. Elk that tested positive in the field were fitted with a GPS collar and, if pregnant, implanted with a vaginal implant transmitter (VIT). Seronegative elk were also collared bringing the total to 30 elk receiving GPS collars in HD 325. Five seropositive elk were detected in HD 325 and no elk tested positive for exposure to brucellosis in HD 329. Seven seropositive elk originally captured in the Blacktail/Sweetwater Hills (HDs 324 and 326) in 2010-2011 were recaptured, implanted with a VIT if pregnant, and tracked to collect samples at birth sites. Of the seven recaptured seropositive elk from HD’s 324 and 326 and the five seropositive elk in HD 325, nine were pregnant and received VITs. Of those nine, one died from unknown causes, two had stillborn or aborted calves and the remainder carried their calves to full term, defined for this project as a birth event occurring May 15th or later with no evidence of an abortion event occurring. Samples collected from the birth site of the two stillborn/aborted calves were culture positive for Brucella abortus biovar 1. Samples from the remaining birth sites and the mortality were culture negative.