Mycoplasma ovis infection in domestic sheep (Ovis aries) in the United States: prevalence, distribution, associated risk factors, and associated outcomes

Authors: URIE, NATALIE - Animal And Plant Health Inspection Service (APHIS); Highland, Margaret; KNOWLES, DOANLD - Washington State University; BRANNAN, MATTHEW - Animal And Plant Health Inspection Service (APHIS); Herndon, David; MARSHALL, KATHERINE - Animal And Plant Health Inspection Service (APHIS)

Submitted to: Preventive Veterinary Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/19/2019
Publication Date: 11/1/2019
Citation: Urie, N.J., Highland, M.A., Knowles, D.P., Brannan, M.A., Herndon, D.R., Marshall, K.L. 2019. Mycoplasma ovis infection in domestic sheep (Ovis aries) in the United States: prevalence, distribution, associated risk factors, and associated outcomes. Preventive Veterinary Medicine. 171. https://doi.org/10.1016/j.prevetmed.2019.104750.
DOI: https://doi.org/10.1016/j.prevetmed.2019.104750

Interpretive Summary: Mycoplasma ovis is blood-borne bacterium, reported to infect sheep, goats, and deer species that can cause anemia, jaundice, and ill-thrift. Although of worldwide distribution, only rare reports of this bacterium in the United States exist. The objective of this study was to identify the prevalence, distribution, and management-associated risk factors of M. ovis infection in domestic sheep (Ovis aries) in the United States.In 2001 and 2011 blood was collected from sheep across the United States as part of the the USDA-APHIS-Veterinary Services’ National Animal Health Monitoring Systems program (NAHMS). In 2015-2016, the USDA-ARS Animal Disease Research Unit tested blood (serum) samples from these collections for the presence of M. ovis. Data from 19,667 sheep on 1,182 operations were analyzed. The overall in-flock presence was 82.7% and the mean within-flock prevalence was 28.6%. Operations in the Central and West region in 2011 had significantly higher in-flock presence of M. ovis and a higher within-flock prevalence. Medium and large operations and operations that vaccinated had a higher in-flock presence and increased in-flock prevalence. Lastly, operations that did not require pre-purchase testing and preventive care on new additions or that utilize public lands grazing were more likely to have M. ovis present. Follow up research is underway to determine the impact of M. ovis, if any, on production.

Technical Abstract: Mycoplasma ovis is a hemotropic bacterium, reported to infect sheep, goats, and deer species that can cause anemia, jaundice, and ill-thrift. Although of worldwide distribution, only rare reports of this bacterium in the United States exist. The objective of this study was to identify the prevalence, distribution, and management-associated risk factors of M. ovis infection in domestic sheep (Ovis aries) in the United States. In 2001 and 2011 blood was collected from sheep across the United States as part of the the United States Department of Agriculture (USDA), Animal Plant Health Inspection Services, Veterinary Services’ National Animal Health Monitoring Systems program (NAHMS). In 2015 the USDA, Agricultural Research Services, Animal Disease Research Unit received aliquots of serum collected during each year, and DNA was extracted and analyzed by PCR for the presence of M. ovis genomic DNA. Data from 19,667 sheep on 1,182 operations were analyzed. The overall in-flock presence was 82.7% and the mean within-flock prevalence was 28.6%. Backward elimination model selection was used after univariate screening to determine which demographic and management variables significantly affected in-flock presence and within-flock prevalence. The final in-flock presence model and within-flock prevalence models included year of blood collection, region, interaction between year and region, operation size, and vaccine administration. Pre-purchase testing requirements and preventive care and grazing on public land were also included in the final in-flock presence model. Operations in the Central and West region in 2011 were more likely to have M. ovis present and have a higher within-flock prevalence. Medium and large operations and operations that vaccinated had a higher in-flock presence and increased in-flock prevalence. Lastly, operations that did not require pre-purchase testing and preventive care on any new additions or that grazed sheep on public land were more likely to have M. ovis present.