Abstract
Bovine viral diarrhea (BVD) is controlled in many countries by detection and culling of persistently infected (PI) animals. The most important risk factor for BVDV introduction is purchase. An introduced cow can be PI and transmit the virus to other cattle in the herd. If she is not PI but is pregnant, there is still a risk because the subsequently born calf may be PI, when she encountered the virus in early pregnancy. To control this risk, all cows > 1 year from non-BVDV-free herds that are introduced in herds that participate in the Dutch BVDV control program are tested for virus and antibodies. Depending on the results, subsequent measures such as suspension of the BVDV-free status, removing the animals from the herd, or testing the off-spring of the cow for virus, are undertaken. The aim of this study was to evaluate the results of this risk mitigating measure. Data on cattle movements, calving's, herd-level BVDV status, and animal-level test data were available from all dairy herds that participated in the national BVDV control program (>14,000 dairy herds) for the year 2019. The data were combined and parameters of interest were calculated, i.e., (i) the number of purchased BVD virus positive cattle and (ii) the number of BVD virus positive calves born from purchased cows within 9 months after introduction. In 2019, 217,301 cattle were introduced in Dutch dairy herds that participated in the BVDV control program. Of these, 49,820 were tested for presence of BVD virus and 27 (0.05%) cows introduced in 21 different herds tested BVD virus positive. Out of 46,727 cattle that were tested for antibodies, 20.5% tested positive. The seropositive cows produced 4,341 viable calves, of which 3,062 were tested for virus and subsequently, 40 (1.3%) were found BVD virus positive. These 40 BVD virus positive calves were born in 23 herds. The risk mitigating measure led to detection of 67 BVD virus positive animals in 44 unique herds in 2019. This study makes plausible that the probability and impact of re-introduction of BVDV can be minimized by testing introduced cattle and their subsequently born calves.
Highlights
Bovine viral diarrhea virus (BVDV) is a pestivirus belonging to the Flaviviridae family [1]
The risk ofintroducing BVDV through purchase of cattle in herds that participate in the national Dutch BVDV-free program is limited
In a country or region that has a successful BVDV control program in place, the prevalence of BVDV will decrease, which leads to an increased proportion of susceptible cattle in the population
Summary
Bovine viral diarrhea virus (BVDV) is a pestivirus belonging to the Flaviviridae family [1] It was first discovered in New York dairy herds in 1946 and in the same year in Canada and is since an endemic cattle disease in many parts of the world [2]. When a pregnant animal encounters the virus for the first time between day 42 and 125 of gestation, the immune system of the fetus is not fully developed and the virus will persistently infect the fetus [3, 4] These cattle pregnant with PIs are called Trojan cows. Due to the continuous shedding of large amounts of virus, PIs are the most important source of the virus and the main reason why herds remain infected [5] Besides this vertical route of infection, BVDV can spread horizontally. Several European countries or regions have implemented bovine viral diarrhea virus programs [10] to control and eradicate the virus
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
