Molecular survey of infectious agents associated with bovine respiratory disease in a beef cattle feedlot in southern Brazil

Abstract

We investigated the occurrence of infectious pathogens during an outbreak of bovine respiratory disease (BRD) in a beef cattle feedlot in southern Brazil that has a high risk of developing BRD. Nasopharyngeal swabs were randomly collected from steers ( n = 23) and assessed for the presence of infectious agents of BRD by PCR and/or RT-PCR assays. These included: Histophilus somni, Mannheimia haemolytica, Pasteurella multocida, Mycoplasma bovis, bovine respiratory syncytial virus (BRSV), bovine coronavirus (BCoV), bovine viral diarrhea virus (BVDV), bovine alphaherpesvirus 1 (BoHV-1), and bovine parainfluenza virus 3 (BPIV-3). Pulmonary sections of one steer that died with clinical BRD were submitted for pathology and molecular testing. The frequencies of the pathogens identified from the nasopharyngeal swabs were: H. somni 39% (9 of 23), BRSV 35% (8 of 23), BCoV 22% (5 of 23), and M. haemolytica 13% (3 of 23). PCR or RT-PCR assays did not identify P. multocida, M. bovis, BoHV-1, BVDV, or BPIV-3 from the nasopharyngeal swabs. Single and concomitant associations of infectious agents of BRD were identified. Fibrinous bronchopneumonia was diagnosed in one steer that died; samples were positive for H. somni and M. haemolytica by PCR. H. somni, BRSV, and BCoV are important disease pathogens of BRD in feedlot cattle in Brazil, but H. somni and BCoV are probably under-reported.

Microbial diversity involved in the etiology of a bovine respiratory disease outbreak in a dairy calf rearing unit

“…This study also represents the first South American report of molecular detection of BRD mixed infections in calves with clinical signs respiratory disease. The results obtained in the current study add to what was described on pathogens associated with BRD in dairy calves [6], since most studies of BRD infections were conducted in feedlot cattle [2,10,18,37].…”

“…The calf rearing units have been used for many years in veal calf and cattle feedlots; however, it is currently also being adapted for calves from dairy herds. Calves are transported from different herds of origin shortly after birth [14] or until the second week of age [15,16] to the dairy calf rearing units or veal calf feedlots, while calves for feedlots are transported only after weaning [17,18]. In the specialized heifer calf rearing units, the outbreaks of BRD in calves are commonly reported [15].…”

Molecular characterization of Brazilian wild-type strains of bovine respiratory syncytial virus reveals genetic diversity and a putative new subgroup of the virus

“…The main bacterial agents are Mannheimia haemolytica, Mycoplasma bovis, Pasteurella multocida, and Histophilus somni (Panciera and Confer 2010, Gershwin et al 2015. Bovine respiratory disease virus (BRSV), bovine viral diarrhea virus (BVDV), bovine alphaherpesvirus 1 (BoHV-1), bovine parainfluenza virus 3 (BPIV-3), and bovine coronavirus (BCoV) are the possible viral causes of BRD (Beuttemmuller et al 2017, Headley et al 2018). Among these microorganisms, BRSV is frequently associated with BRD (Apley 2006, Grissett et al 2015.…”

Identification of novel drug targets in bovine respiratory disease: an essential step in applying biotechnologic techniques to develop more effective therapeutic treatments

“…2 – 6 BRD is caused by multiple factors, including a combination of bacterial and viral components. 7 , 8 Associated factors such as environmental and stress-related exposures (eg, weaning and transportation) also play a part. 9 – 14 According to data provided by the Canadian Cattlemen Association, BRD accounts for 65%–80% of the sickness in some feedlots, 45%–75% of the death loss, and an annual loss of about US$ 600–750 million to the North America beef industry.…”