Eradication of Bovine Respiratory Syncytial Virus in Sweden?!

Uppsala, June 2017

Sweden was one of the first countries worldwide that managed to eradicate BVDV (Bovine Viral Diarrhea Virus) and is officially free since2014. The SVANOVIR® BVDV-Ab assay was one instrument in this effort. Now, 5 years later, Bovine Respiratory Syncytial Virus (BRSV) is tackled by Växa Sverige, the Swedish Farmer and Livestock Association, and SVANOVIR® BRSV-Ab is part of this effort.


Anna Ohlson is a veterinarian at Växa Sverige and responsible for the BRSV program. BRSV is one part of the surveillance program”safe animal trade” where exposure to important infectious diseases is assessed and managed. Anna has done her PhD at the Swedish University of Agricultural Sciences (SLU), Uppsala about BRSV and Bovine Coronavirus together with Prof. Stefan Alenius (editorial note: he is the mastermind behind the Swedish BVDV eradication program).


What is the rationale behind the program?

Sweden is free of BVDV, IBR and BLV, so BRSV is one of the major threats to cow health and farmers’ economy. Purchase of a new stock poses a significant risk and controlling this risk offers a high return. In Sweden farmers tend to purchase new stock frequently, around 50% of operations purchase new stock from other sites and half of them do not keep the animals in quarantine. This program will help to manage risks and prevent transmission of BRSV.


BRSV is highly infectious, why will you succeed with controlling it?

We know that the disease is not airborne and simple biosecurity measures such as farm related boots/clothes for visitors can prevent transmission. Furthermore the BRSV does not stay a long time in the herd. Knowing the BRSV- status tells a lot about effectiveness of current biosecurity measures. A positive result indicates that the biosecurity is not stringent enough and we need to put effort in improving the management routines. In contrast, a negative status is very motivating and farmers take the opportunity for premium pricing of calves and cows.


What is the prevalence of BRSV in Sweden?

We did a national prevalence study on primiparous cows from around 1500 operations in 2016. The average prevalence was 45%, percent positives varied between 63% and 0%. Operations in the southwest were more frequently positive than operations in the northeast. However, even in the southern parts where the BRSV was circulating, many herds where negative for antibodies in primiparous cows. This clearly shows that biosecurity strategies are working and indicates that in the long term Sweden can become free of BRSV.


What does the program look like?

We will take routine milk samples from 1-3 primiparous cows 1-2 times per year and check for the prevalence of antibodies. This will be part of a voluntary sampling program dairy operations are undergoing. It is also possible to check for your BRSV status before you want to sell livestock. The operations that are negative for specific diseases e.g. Mycoplasma bovis, Staphylococcus aureus and Salmonella are then listed in the what we call “green list”. Since 2017 also their BRSV status is shown. Farmers that are planning to purchase animals can use the green list to select stock from other negative operations.


 



Why are you using the SVANOVIR® BRSV-Ab for this program?

I have done a couple of validation studies on this and other assays (SVANOVIR® BCV-Ab) in Sweden together with Stefan Alenius (Ohlson, 2010). The assays are highly specific so we had no false positives in the operations from the Northern part and there is a good correlation between serum and milk samples (Ohlson et al., 2014). I know that the laboratory acknowledges that both, serum and milk samples can be run on the same plate and Svanovas assays are of high quality.

If you have further questions about the program, please contact kontrollprogram@vxa.se and for questions about the Svanovir assays, please contact info@svanova.com




References:

Ohlson, A. (2010): Bovine Coronavirus and Bovine Respiratory Syncytial Virus Infections in Dairy Herds, prospects for control. Doctorate thesis, Swedish University of Agricultural Sciences, ISSN 1652-6880

Ohlson, A., et al. (2014): Comparison of Bovine coronavirus-specific and Bovine respiratory syncytial virus-specific antibodies in serum versus milk samples detected by enzyme-linked immunosorbent assay. Journal of Veterinary Diagnostic Investigation, 26 (1), pp. 113-116