Prevalence of respiratory viruses and Mycoplasma bovis in U.S. cattle and variability among herds of origin, production systems and season of year

摘要

Bovine respiratory disease (BRD] is a significant cause of morbidity and mortality in beef and dairy calves in the United States. Although BRD is multifactorial in nature, viral infection often precedes bacterial infection; thus, diagnostic investigations often consider both bacterial and viral components of the disease. Prevalence estimates of respiratory viruses and Mycoplasma bovis would aid in the interpretation of diagnostic results. Therefore, the objective of this study was to determine the prevalence of bovine respiratory agents (bovine viral diarrhea virus, bovine respiratory syncytial virus, bovine respiratory coronavirus, bovine herpesvirus-1, influenza D virus, and M. bovis) in US cattle. Nasopharyngeal swabs (n=3205] were collected fromcow-calf, dairy, feedlot, and stocker operations and tested for these respiratory agents using a multiplex PCR. Estimates of animal-level prevalence and associations with herd of origin, production system, and season of year were determined. Bovine coronavirus was the most prevalent respiratory agent with an overall animal-level prevalence of 36.05%, and was significantly associated with production class (highest in stocker) and season (fall). Mycoplasma bovis and influenza D virus were also detected frequently in this population of cattle, while bovine viral diarrhea, bovine herpesvirus-1, and bovine respiratory syncytial virus were detected in less than 5% of samples. The relatively high prevalence of bovine coronavirus and influenza D suggest thatpractitioners should consider testing for these agents as part of routine BRD diagnostic investigations.