Bovine respiratory syncytial virus seroprevalence and risk factors in feedlot cattle from Córdoba and Santa Fe, Argentina / Seroprevalencia del virus respiratorio sincicial bovino y factores de riesgo asociados en engordes a corral de Córdoba y Santa Fe, Argentina

Bovine respiratory syncytial virus (BRSV) is one of the causative agents of respiratory disease in cattle all over the world, leading to important economic losses. The aim of this work was to determine the seroprevalence of BRSV in feedlot cattle of Argentina and the risk factors associated with the disease. Results showed a high individual seroprevalence of 78.64% (95% confidence interval adjusted -#91;CI-#93; =66.55-90.75%) against the virus. Positive association was found between the presence of high BRSV neutralizing antibody titers, and the following risk factors: cattle age, source of animals, presence of clinical respiratory signs and herd size. This work contributes to updating the understanding of its epidemiology in Argentinean feedlots and poses the need for reevaluating vaccination strategies against this virus in order to control infection and its impact on productivity.

El virus respiratorio sincicial bovino (BRSV) es uno de los agentes causantes de enfermedad respiratoria bovina a nivel mundial, conduciendo a importantes pérdidas económicas. El objetivo de este trabajo fue determinar la seroprevalencia del BRSV en bovinos de engorde a corral de Argentina y estudiar los factores de riesgo asociados. Los resultados mostraron una elevada seroprevalencia individual del 78,64% (IC = 66,55-90,75%) contra el virus. Se encontró una asociación positiva entre la presencia de altos títulos de anticuerpos neutralizantes contra BRSV y los factores de riesgo: edad del ganado, origen de los animales, presencia de signos clínicos respiratorios y el tamaño del rebano. Este trabajo contribuye en gran medida a la comprensión de la epidemiología en los establecimientos de engorde a corral de Argentina y plantea la necesidad de revaluar las estrategias de vacunación contra este virus con el fin de controlar la infección y su impacto en la producción.

[Molecular and histopathological findings on induced pulmonary lesions by bovine viral diarrhea virus]

The bovine viral diarrhea virus [BVDV] is one of the bovine respiratory system pathogens that represses lungs immunity and raises the pathogenicity of other bacteria and viruses. The aim of the present study was to evaluate the effect of BVDV in lung tissue. In this study, 30 bovine lung tissues were used. Histopathologic analysis showed different lesions in lung tissues. RT-PCR test results and histopathologic observations were studied for each sample and compared. Kai Square Test was used to study any possible association between the existence of BVD virus and incidence of four common lesions: 1- Interestitial pneumonia, 2- bronchitis and bronchiolitis, 3- edema, emphysema and atelectasis and 4- bronchopneumonia. If the assumptions of X2 test were not applicable, the Fisher Exact Test was used. The RT-PCR test for BVDV results was positive for 10 lung samples. 5 BVD positive cases were involved with interestitial pneumonia, while 10 BVD negative cases were not affected. Finally, in the studied lung tissues, only the 3 + degree or severe interstitial pneumonia was significantly associated with the existence of BVD virus. No significant relation was seen regarding other possible lesions, which may have resulted from the probable roles of bacteria or other viruses and toxic factors that were not studied in this project