Comparison of bison and elk susceptibility to experimental challenge with Brucella abortus strain 2308

Authors: Olsen, Steven; Boggiatto, Paola; Putz, Ellie

Submitted to: Frontiers in Veterinary Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/23/2024
Publication Date: 1/15/2025
Citation: Olsen, S.C., Boggiatto, P.M., Putz, E.J. 2025. Comparison of bison and elk susceptibility to experimental challenge with Brucella abortus strain 2308. Frontiers in Veterinary Science. 11. Article 1519453. https://doi.org/10.3389/fvets.2024.1519453.
DOI: https://doi.org/10.3389/fvets.2024.1519453

Interpretive Summary: Brucellosis is a zoonotic disease of domestic livestock and wildlife that causes abortions and reproductive losses. In the United States, bison and elk in Yellowstone National Park and surrounding areas are infected with brucellosis and routinely transmit the disease to cattle herds. New intervention strategies to control brucellosis in both domestic livestock and wildlife reservoirs are needed. In this manuscript we report that bison are more susceptible to brucellosis than elk and have higher levels of infection and abortion. Elk Vaccination of bison, but not elk, reduced abortions and infection, when compared to non-vaccinates. Our data suggests that brucellosis differs between bison and elk and that intervention strategies may need to be species-specific.

Technical Abstract: A comparative study was conducted using data from naive (n=82 and 67, respectively) and Brucella abortus strain RB51 vaccinated (n-99 and 29, respectively) bison and elk experimentally challenged with virulent B. abortus strain during pregnancy. The incidence of abortion, fetal infection, uterine or mammary infection, or infection in maternal tissues after experimental challenge was greater (P<0.05) in naïve and vaccinated bison when compared to similar groups in elk. Bison vaccinated with RB51 had lower (P<0.002) abortion rates and recovery of Brucella from fetal or uterine/mammary tissues when compared to naïve bison. Vaccinated elk had reduced (P<0.01) rates of maternal infection, but rates of abortion and fetal or uterine/mammary infection did not differ (P>0.05) from naïve elk. In elk or bison that aborted, time between experimental challenge and parturition was less (P<0.05) than in animals delivering full-term calves. In both naïve and vaccinated bison colonization in some target tissues draining the site of infection, mammary gland, or reproductive tissues was greater (P<0.05) than similar treatments in elk. In elk or bison that aborted, colonization in placentomes was typically more than 5 logs higher than in animals that did not abort. The results of our study suggest differences in disease pathogenesis between the two wildlife reservoirs of brucellosis in the areas surrounding Yellowstone National Park. These observations suggest brucellosis intervention strategies for bison and elk may need to be species-specific.