Simulating sterilization, vaccination, and test-and-remove as brucellosis control measures in bison

Ecological Applications
By: , and 



Brucella abortus, the causative agent of bovine brucellosis, infects wildlife, cattle, and humans worldwide, but management of the disease is often hindered by the logistics of controlling its prevalence in wildlife reservoirs. We used an individually based epidemiological model to assess the relative efficacies of three management interventions (sterilization, vaccination, and test-and-remove). The model was parameterized with demographic and epidemiological data from bison in Yellowstone National Park, USA. Sterilization and test-and-remove were most successful at reducing seroprevalence when they were targeted at young seropositive animals, which are the most likely age and sex category to be infectious. However, these approaches also required the most effort to implement. Vaccination was less effective (even with a perfect vaccine) but also required less effort to implement. For the treatment efforts we explored (50–100 individuals per year or 2.5–5% of the female population), sterilization had little impact upon the bison population growth rate when selectively applied. The population growth rate usually increased by year 25 due to the reduced number of Brucella-induced abortions. Initial declines in seroprevalence followed by rapid increases (>15% increase in 5 years) occurred in 3–13% of simulations with sterilization and test-and-remove, but not vaccination. We believe this is due to the interaction of superspreading events and the loss of herd immunity in the later stages of control efforts as disease prevalence declines. Sterilization provided a mechanism for achieving large disease reductions while simultaneously limiting population growth, which may be advantageous in some management scenarios. However, the field effort required to find the small segment of the population that is infectious rather than susceptible or recovered will likely limit the utility of this approach in many free-ranging wildlife populations. Nevertheless, we encourage scientists and policy makers to consider sterilization as part of a suite of available brucellosis management tools.
Publication type Article
Publication Subtype Journal Article
Title Simulating sterilization, vaccination, and test-and-remove as brucellosis control measures in bison
Series title Ecological Applications
DOI 10.1890/10-2239.1
Volume 21
Issue 8
Year Published 2011
Language English
Publisher Ecological Society of America
Contributing office(s) Northern Rocky Mountain Science Center, Contaminant Biology Program
Description 16 p.
First page 2944
Last page 2959
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