A serological investigation of the thirty-year history of exposure to Mycoplasma bovis in healthy North American bison

Authors: REGISTER, KAREN; WOODBURY, MURRAY - UNIVERSITY OF SASKATCHEWAN; JONES, LEE - U.S. FISH AND WILDLIFE SERVICE; HUNTER, DAVID - TURNER ENDANGERED SPECIES FUND; NOL, PAULINE - ANIMAL AND PLANT HEALTH INSPECTION SERVICE (APHIS)

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 3/28/2017
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Mycoplasma bovis causes mastitis, pneumonia and arthritis in cattle and is a major contributor to bovine respiratory disease complex. Recently, it has emerged as a significant respiratory and reproductive health problem in bison. Understanding why M. bovis, known to cause disease in cattle for over 55 years, has only recently emerged as a pathogen in bison, a host it was not known to infect prior to roughly the year 2000, would be of benefit in formulating strategies to minimize its impact on bison health and production. As a first step in understanding the recent appearance of disease in bison due to M. bovis, this study was designed to answer two basic questions: 1) Is there serological evidence for M. bovis exposure/infection in clinically healthy bison prior to the time the bacterium emerged as a disease problem?; and 2) Is there serological evidence for M. bovis exposure/infection in clinically healthy bison after its emergence as a disease problem? A total of 2790 sera from bison in the U. S. (n = 959) or Canada (n = 1831), collected between 1984 and 2015, was tested for antibodies to M. bovis, of which 200 (7.2%) tested positively. The proportion of positive sera in samples from a single source ranged from 0 - 66.7%. Considering the 2634 sera for which the year of collection is known, 7.3% (106/1453) from 1999 or prior tested positively while 7.1% (84/1181) collected in 2000 or later were positive. To evaluate the potential effect of management status, data were categorized according to the management practices utilized with the bison from which sera were obtained. Relevant information is available for 2126 sera representing 30 unique sources, 17 in Canada and 13 in the U.S. Overall, 7.7% (89/1152) of sera from farmed bison were positive as compared to 4.6% (45/974) from bison that were minimally managed. Considering sera for which both the year of collection and management practices are known (n = 1971, from the same 30 sources noted above), for minimally managed bison the proportion testing positively among samples collected prior to 2000 versus those collected in 2000 or later is nearly equivalent, 4.9% (13/266) versus 4.2% (23/553), respectively. For farmed bison, 5.3% (28/526) of samples collected prior to 2000 are positive, versus 9.7% (61/626) of samples from 2000 or later. These data suggest that colonization of bison by M. bovis may not necessarily lead to apparent disease, which has important implications for serological monitoring in bison. Prevalence in farmed bison appears to have risen in recent years but seems relatively stable in minimally managed bison. M. bovis appears to have been resident in healthy bison since at least the 1980’s, long before its recognition as a disease problem. This observation lends support to the theory that newly evolved, novel genotypes may underlie the recent appearance of related disease in bison. Additional support for that concept is provided by ongoing genetic analysis and comparison of isolates from cattle and bison.