Evaluating Two Sampling Methods for Mycoplasma Bovis Diagnosis in American Bison (Bison bison)

Area of Science:

• Wildlife disease ecology
• Bacterial pathogenesis
• Conservation medicine

Background:

• Mycoplasma bovis is a cattle pathogen that emerged in American bison, causing significant respiratory disease and mortality.
• Bison herds with M. bovis outbreaks face higher risks of recurrence, indicating potential for chronic, subclinical infections.
• Accurate antemortem testing is vital for effective M. bovis disease management in bison populations.

Purpose of the Study:

• To evaluate the sensitivity and agreement of superficial nasal swabs versus deep nasopharyngeal swabs for M. bovis detection in bison.
• To determine the optimal sampling method for maximizing M. bovis detection in both healthy and symptomatic bison.
• To assess the feasibility of pooled PCR testing for increased throughput and cost reduction in M. bovis surveillance.

Main Methods:

• Real-time PCR was used to detect M. bovis in superficial nasal swabs and deep nasopharyngeal swabs from 938 bison across 11 herds.
• Bison were sampled between January 2021 and December 2022, including apparently healthy and symptomatic individuals.
• Pooled samples (up to five) were also tested by PCR to evaluate efficiency.

Main Results:

• M. bovis was detected in 8.1% (76/938) of tested bison.
• Deep nasopharyngeal swabs detected M. bovis in 82.8% of positive bison, compared to 38.1% for superficial nasal swabs.
• Low agreement (21%) between swab types suggests differences in sensitivity possibly related to infection stage; pooled sampling up to five samples proved effective.

Conclusions:

• Deep nasopharyngeal swabbing is significantly more sensitive for detecting M. bovis in bison than superficial nasal swabbing.
• The low agreement between methods may reflect varying stages of M. bovis infection within individuals.
• Effective diagnostic strategies, including pooled PCR, are essential for managing bison health, conservation, and preventing disease transmission.