Scientists Counter Brucellosis Threat to Livestock and Wildlife

Armed with dart guns and medical pellets, Agricultural Research Service (ARS) scientists are vaccinating bison at the ARS National Animal Disease Center (NADC) in Ames, Iowa, in support of Yellowstone National Park activities to combat brucellosis in bison.

The researchers are using a vaccine known as RB51. By vaccinating the bison, scientists hope to prevent the disease from spreading to livestock. Currently, no cattle herds in the U.S. are known to be infected, although some near Yellowstone have tested positive in the last decade, with elk being the suspected source.

Brucellosis, an incurable disease, can cause abortions in cattle, bison, elk, and feral swine. It can be transmitted to humans through contact with infected animals or consumption of unpasteurized dairy products. In humans, it's called undulant fever, and causes severe flu-like symptoms.

Wildlife reservoirs of brucellosis in the United States include bison and elk (which carry Brucella abortus) and feral swine (which carry B. suis).

Steven Olsen, a veterinary medical officer at NADC, has led the team on the bison vaccination study. During the project, researchers monitored animals at NADC to determine the natural course of B. abortus in female bison and their offspring. They found that in bison, the disease mimics the characteristics seen in cattle.

Brucellosis has been nearly eradicated in the United States, mostly through cooperative federal and state programs dating back to the 1950s. But its continued presence in the Greater Yellowstone area has rekindled concern among cattle producers.

Among the concerns of Olsen and his colleagues—microbiologists Fred Tatum and Betsy Bricker—is the difficulty in diferentiating between B. abortus and B. suis. This presents difficulties for federal officials because a national brucellosis eradication program only targets B. abortus.

The National Park Service is conducting an environmental impact study on a proposed remote vaccination program for Yellowstone National Park bison, with the end goal of reducing the prevalence of brucellosis in the park herd.

ARS is the principal intramural scientific research agency of the U.S. Department of Agriculture. The results of this study have been published in the journal Vaccine.