BVDV control in Europe
A significant part of the work has dealt with issues pertaining to the process that lead up to initiation of control. Furthermore, current knowledge on the virus, its prevalence, diagnostic abilities and immunoprophylactic approaches has been analysed to identify areas of future research considered necessary to support available control approaches. The network has also set out to formulate a general model for BVDV control and describe how this model applies to the prospect of making progress once control has been initiated.
Schemes to eradicate BVDV
A main conclusion of the network is that the technical tools and the knowledge needed for eradicating BVDV are at hand. Several EU Member States have already embarked on large scale schemes, where some are close to finalisation. Three central elements of such schemes are:
- the implementation of biosecurity aimed at preventing re-introduction of the infection in free herds;
- elimination of persistently infected (PI) animals from infected herds; and
- continuous surveillance to monitor progress of the interventions and to rapidly detect new infections.
The network has chosen to term this type of approaches “systematic”, in contrast to control efforts with diffuse goals and without surveillance in place to evaluate progress.
In this systematic context, biosecurity involves all measures that support prevention of between-herd transmission of BVDV, including the more abstract but important risk-reducing effects of a common regulatory framework (voluntary or compulsory), of measures aimed at increasing the general awareness of BVDV risks among stakeholders and of swift access to accurate and updated information on herd or animal BVDV status for decision making in conjunction with livestock trade and other herd contacts. Although basic biosecurity measures can be implemented on any farm, there are substantial benefits in terms of cost-efficiency by implementing control at a larger scale (regional/national). This will have a greater effect on reducing the overall risk of between-herd spread, which is a strong determinant for the cost-benefit of BVDV control.
The network thus concludes that a systematic approach is needed if the goal is a long-term reduction in the incidence and prevalence of BVDV infections in Europe. Systematic control and eradication programmes have been shown to have the potential of being highly cost-effective. Strongly contributing to this is the ability to use low cost-high throughput herd level screening tools, but also the dramatic decrease in incidence of new infections seen after implementation of biosecurity, as defined above. This ability to show good progress is also of great importance in order to maintain support from the primary stakeholders.
The role of vaccines in systematic control is an additional biosecurity measure. In areas where the risk of introducing BVDV infection is known or perceived to be high, one option is to implement systematic vaccination of cattle against BVDV in initial stages of control/eradication programmes, after removal of PI animals. The need for including a vaccination regime will differ between countries/regions and it will also change over time, as the prevalence of infected herds decreases. Since adding a vaccination regime also implies an additional cost, it should be evaluated against the expected benefits on a regular basis.
There is a series of issues with the use of vaccines that need to be considered before including vaccination in a systematic control/eradication scheme. These issues include the need to ensure compliance and the fact that vaccination interferes with interpretation of serological test results but there are also safety and efficacy issues with the vaccines themselves.
EU thematic network on BVDV control position paper: executive summary
Although there are solutions for how they can be mitigated, it is vital that this aspect it given thorough consideration and that stakeholders are well informed of any risks and shortcomings of vaccines before large-scale vaccination is implemented.
As a consequence of the ongoing national BVDV control programmes in Europe, differences in prevalence of BVDV infections are becoming increasingly pronounced. Politically, these differences are reflected in the acknowledgement of BVD as a notifiable disease in eight European countries; Austria, Belgium, Denmark, Finland, Germany, Norway, Sweden and Switzerland. This together with the recent decision by the OIE to list BVD as a priority disease in terms of animal trade is a strong signal to the Community to consider development of an EU wide strategy to control BVD.
Such a strategy must account for the economic, social and political differences that influence disease control in general. The economic incentives to initiate BVDV control may be present in many regions - at the farm as well as at higher levels. Nevertheless the experience is that a strong motivating factor for initiation and positive progress of control programmes is if the initiative is taken by organisations that directly or indirectly represent the primary stakeholders. Thus, if BVD is acknowledged as a priority by policy makers at the EU level, incentives should be created for farmers’ cooperative bodies or similar organisations to take an active role in initiating control programmes. The use of public funding to support such initiatives, e.g. for baseline surveys and/or information campaigns, could be justified in terms of the wider societal benefits, for example to animal welfare.
Beyond Europe, the consequences of the OIE listing of BVD in terms of economic and social pressure for control are yet to be seen. US cattle producers recently responded to the problems associated with BVDV infections by drafting a policy document with the ultimate aim to eradicate BVD from America, and in New Zealand, the scientific community has moved BVD higher up on the industry’s list of priorities. Altogether, there are strong indications that the disease has become an international priority.
With the achievements by Member States so far, and with the concept put forward by this Thematic Network, the EU is in a good position to meet increased standards. But to retain this position, the Union needs to be proactive, both in the political and scientific field.
Continuous improvement of diagnostic tests, and monitoring of their performance, is central for sustainable BVDV control. Similarly, where vaccines are used, there will be a constant need for development and adaptation to evolving strains that circulate in the cattle population.
It is clear that as long as BVDV control efforts are not harmonised across Europe, there will always be a threat of spreading of BVDV across the continent, including the less prevalent BVDV-2 and any new emerging types.
Non-systematic use of any live cattle vaccine can increase this risk. However, efficient systematic control measures with or without the use of vaccines will provide the necessary protection. A future challenge is to find a joint platform where differences in needs and preconditions between Member States can be accommodated, while still promoting concerted action on BVDV control.
With the experiences and tools available today, a pan-European approach to controlling BVDV is feasible. More specifically, it offers a unique opportunity to increase the general biosecurity standards in cattle operations across the union. The principles of systematic BVDV control will, if applied more widely, contribute to the overall stability against introduction and spread of other zoonotic and epizootic agents. Such an effect could be achieved by coordinating further initiatives on the control of BVD with actions directed towards other infectious cattle diseases, where the focus is biosecurity. Such coordination would, in addition to providing a potential for long term improvement in bovine health and welfare, strongly support the future competitiveness of Europe’s cattle industry.
The full report can be downloaded at the link below:
EU thematic network on control of bovine viral diarrhoea virus (BVDV)