Expert Report

Revisiting Brucellosis in the Greater Yellowstone Area (2017)


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An increase in brucellosis cases in the Greater Yellowstone Area has alarmed cattle and domestic bison producers and spurred new scientific analyses to determine the factors involved. Brucellosis is found in cattle, bison, and elk and can result in late-gestation abortion, decreased milk production, and loss of fertility. Although it is not considered a major public health threat in the United States, brucellosis can have serious economic consequences. States must maintain brucellosis class-free status, among other criteria, to sell and move live cattle. The Greater Yellowstone Area is the last known U.S. reservoir of Brucellosis abortus. Between 1998 and 2016, 22 cattle herds and five privately-owned bison herds were affected in Idaho, Montana, and Wyoming; all other states are free of the disease.

Although eradication of brucellosis remains a distant goal due to scientific, social, political, and economic reasons, significant progress can be made toward reducing or eliminating brucellosis transmission from wildlife to domestic species. Recent evidence indicates control efforts should focus on reducing risk of transmission from elk, which are now viewed as the primary source of the infection in new cases occurring in cattle and domestic bison. The report lays out several management options that can help reduce transmission such as reducing the elk population by hunting, contraception trials in elk, and testing and removing brucellosis infected elk. Another potential tool is the incremental closing of supplemental feedgrounds for elk where brucellosis is known to spread.

This report concludes that significant efforts and resources are needed to address the increase in brucellosis cases and prevent the spread of the disease beyond the Greater Yellowstone Area. Federal and state agencies and tribal jurisdictions involved in controlling the disease should adopt an active adaptive management approach that includes hypothesis testing and periodic scientific assessments to guide management decisions. Coordination is needed at the highest federal (Secretary) and state (Governor) levels. The report also calls for the development of a strategic plan to coordinate future efforts and fill in critical knowledge and information gaps.

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