Maintenance of sub clinical Mycoplasma bovis infections in American bison (Bison bison) in the absence of detectable transmission

Authors: BUTTKE, DANIELLE - Us National Park Service; Kaplan, Bryan; JONES, LEE - Us Fish And Wildlife Service; KRUS, CATHERINE - Colorado State University; FELTNER, JEN - Us National Park Service; MALMBERG, JENNIFER - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Journal of Wildlife Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: Mycoplasma bovis (M. bovis) is a bacteria that causes severe respiratory disease with high mortality in American bison and its continued presence in bison herds has had a detrimental impact on bison ranching that also threatens bison health and restoration. Despite the significant threat posed by M. bovis, little is known about important clinical aspects of the disease, including the duration of infection, disease transmission, and the immune response to infection; information which is critical to improve herd management decisions following M. bovis outbreaks. In this study we continue the surveillance of a cohort of naturally infected bison calves. Most of the cohort developed an antibody response to infection that diminished over a 24 month period however, two animals continued to produce high antibody levels beyond 24 months. Co-mingling of 4 naive bison with the cohort did not lead to transmission of M. bovis to these uninfected, contact animals. The data presented here begin to address key knowledge gaps that may assist in controlling M. bovis infection in bison.

Technical Abstract: Mycoplasma bovis is a growing threat to bison health and restoration efforts, causing significant mortality and disease in affected bison herds. Despite these implications, little is known about the epidemiology or clinical course of M. bovis infection in bison. In this study, we present continued observations from a cohort of naturally infected American bison, in which maintenance of subclinical M. bovis infections was previously reported. Most (n=8/11) surviving previously infected animals mounted a detectable IgG response that waned within 6-24 months. Two bison mounted and maintained robust IgG antibody responses throughout the study period, one of which also remained PCR and culture positive throughout the study. One animal failed to mount a detectable IgG response despite becoming infected with M. bovis during the study. Additionally, naïve animals (n=4) were added to the environment where positive animals had been previously kept, shared a water tank with known positive animals, and were finally added to the cohort and sampled at 3-month intervals for a 2 year follow up period. The four naïve animals remained M. bovis negative despite commingling with known positive animals in the cohort. We discuss limitations of current antemortem test approaches and the need for more accurate testing to support healthy bison restoration and management.