control and reduced risk of transmission to cattle." It is unlikely that a vaccination program for bison would succeed without a preliminary or concomitant program for elimination of brucellosis in elk. Re-emergence of brucellosis in a free bison herd is likely to occur if two conditions remain: brucellosis in winter elk feeding grounds is not controlled to prevent reinfection of bison from elk, and bison populations remain high.
Although it has been stated that brucellosis cannot be eradicated from free-ranging wildlife without eradicating the wildlife, it is certain that brucellosis can be eliminated from YNP with combinations of vaccination and culling. However, until a long-term controlled vaccination study is done, no assumptions about whether brucellosis can be eliminated by vaccination should be made. One measure of success would be a reduction in rates of abortion that would directly result in diminished bison-to-cattle and bison-to-bison transmission. Bison are more likely to prevent the long-term elimination of brucellosis from elk than vice versa.