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United States Department of Agriculture

Agricultural Research Service

Research Project: Control of Ovine Respiratory Disease through Genetic and Immunologic Mitigation of Pathogen Transmission and Disease

Location: Animal Diseases Research

Title: Causes of pneumonia epizootics among bighorn sheep, western United States, 2008-2010

item Besser, Thomas -
item Highland, Margaret
item Baker, Katherine -
item Cassirer, Frances -
item Anderson, Neil -
item Ramsey, Jennifer -
item Mansfield, Kristin -
item Bruning, Darren -
item Wolff, Peregrine -
item Smith, Joshua -
item Jenks, Jonathan -

Submitted to: Emerging Infectious Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 16, 2012
Publication Date: March 16, 2012
Repository URL:
Citation: Besser, T.E., Highland, M.A., Baker, K., Cassirer, F.E., Anderson, N.J., Ramsey, J.M., Mansfield, K., Bruning, D.L., Wolff, P., Smith, J.B., Jenks, J.A. 2012. Causes of pneumonia epizootics among bighorn sheep, western United States, 2008-2010. Emerging Infectious Diseases. 18(3):406-14.

Interpretive Summary: This report strongly correlates the presence of Mycoplasma ovipneumoniae in herds of bighorn sheep experiencing population limiting pneumonia. This bacterial pathogen joins the list of organisms that have been identified in lung tissues from bighorn sheep with pneumonia.

Technical Abstract: Epizootic pneumonia of bighorn sheep is a devastating disease of uncertain etiology. To help clarify the etiology, we used culture and culture-independent methods to compare the prevalence of the bacterial respiratory pathogens Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida, and Mycoplasma ovipneumoniae in lung tissue from 44 bighorn sheep from herds affected by 8 outbreaks in the western United States. M. ovipneumoniae, the only agent detected at significantly higher prevalence in animals from outbreaks (95%) than in animals from unaffected healthy populations (0%), was the most consistently detected agent and the only agent that exhibited single strain types within each outbreak. The other respiratory pathogens were frequently but inconsistently detected, as were several obligate anaerobic bacterial species, all of which might represent secondary or opportunistic infections that could contribute to disease severity. These data provide evidence that M. ovipneumoniae plays a primary role in the etiology of epizootic pneumonia of bighorn sheep.

Last Modified: 8/25/2016
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