When a pathogen infects a number of different hosts, the process of determining
the relative importance of each host species to the persistence of the pathogen
is often complex. Removal of a host species is a potential but rarely possible
way of discovering the importance of that species to the dynamics of the
disease. This study presents the results of a 12-year programme aimed at
controlling brucellosis in cattle, sheep and goats and the cascading impacts on
brucellosis in a sympatric population of red deer (Cervus
elaphus) in the Boumort National Game Reserve (BNGR; NE Spain). From
February 1998 to December 2009, local veterinary agencies tested over 36 180
individual blood samples from cattle, 296 482 from sheep and goats and 1047 from
red deer in the study area. All seropositive livestock were removed annually.
From 2006 to 2009 brucellosis was not detected in cattle and in 2009 only one of
97 red deer tested was found to be positive. The surveillance and removal of
positive domestic animals coincided with a significant decrease in the
prevalence of brucellosis in red deer. Our results suggest that red deer may not
be able to maintain brucellosis in this region independently of cattle, sheep or
goats, and that continued efforts to control disease in livestock may lead to
the eventual eradication of brucellosis in red deer in the area.