An epidemiological survey of bovine viral diarrhea infection in calves in Egypt with identification of high prevalence of persistent infected animals

Abstract

In the present study, we identified the persistent infection by bovine viral diarrhea virus (BVDV) in 45 clinically suspected persistent infected (PI) calves and 260 apparently healthy calves from Damietta governorate (North) in Egypt during 2016 using enzyme-linked immunosorbent assay (ELISA), serum neutralization test (SNT), immunohistochemistry (IHC), and reverse transcription polymerase chain reaction (RT-PCR). The identification of PI calves was performed after vaccination by CattleMaster® 4. The age of PI calves in the current study was ranged from 2 to 4 months (n = 7) and from 5 to 8 months (n = 38). ELISA revealed the infection in 4 clinically suspected PI calves (57.14%) aged 2 to 4 months. While the infection did not approve in any of the calves within this age using RT-PCR, for calves aged from 5 to 8 months old, ELISA showed the infection in 30 calves (78.94%), and from these calves, the infection was confirmed in 6 calves (15.79%) only using RT-PCR. For apparently clinically healthy animals, 11 transiently infected calves were identified by IHC (positive), SNT (positive), and RT-PCR (negative) at 2 months' post-vaccination. Collectively, the persistent infection was confirmed in 9 calves (2.95%) out of 305 calves. In summary, our study detected a high prevalence of PI calves with BVDV in Damietta province in Egypt, which highlights the importance of introducing effective prevention and control strategies throughout Egypt to minimize the prevalence of BVDV.

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