BVD eradication in Switzerland—A new approach

Abstract

Diverse concepts for BVD eradication or control have been applied in several countries with varying success. Results of previous studies conducted in Switzerland have shown that the prevalence of antibody-positive animals is high and that BVDV is wide spread in the country causing serious economic losses. A new approach to eradicate BVD in the cattle population in Switzerland was chosen. It consists in testing the whole Swiss cattle population for virus detection in a short period of time, without initial antibody screening.Identified persistently infected (PI) animals have to be slaughtered, and new herd infections should be avoided by movement restrictions. Ear-notches are collected using special tags for labeling the animals, and are analyzed using ELISA or rtRT-PCR Methods. Confirmatory tests if needed are performed on blood samples using rtRT-PCR.The eradication program is divided in four phases: 1) Pre-pasturing phase: all young bovines going to transhumance in summer have to be negative tested before. 2) Initial phase: all non-tested bovines have to be tested. Movement restrictions are effective at the same time. 3) Calves phase: all new-borne calves have to be tested 4) Surveillance phase: several strategies will be compared using a modeling approach.After the pre-pasture phase already 595'230 animals (37% of the livestock) have been tested within four months. A prevalence of 1.1% of PI's was observed. The average age of infected animals is 403 days compared to 794 days for non-infected animals, with the oldest PI animal being over 11 years old. On average PI animals are slaughtered within 18 days after the last positive result.The pre-pasture phase has shown that sampling and testing a high number of animals in a short time is challenging but possible. The next phase will deal with a double amount of animals in a similar time frame. The coordination between all partners as well as the collaboration of farmers is the key factor for ensuring the success of the program.

Reduction of prevalence of persistent BVDV infection in cattle herds by long-term vaccination program (preliminary clinical study)

“…animals used to die early in life, however nowadays screening study, for BVDV persistent infection suggest that many of them may reach maturity (Bolin 1990). Proposed strategies of BVD control and eradication depends on overall prevalence of BVDV infection in cattle population and financial limitations (Bitsch et al 2000, Presi et al 2010. The most important parts of the control programs are detection and elimination currently existing p.i.…”

Evaluation of diagnostic methods to distinguish between calves persistently and transiently infected with bovine viral diarrhoea virus in respect to the presence of maternal antibodies

“…The loads of virus shed by the PIs into the environment are so high that even short contact with such animals may lead to infection in the herd (20). BVDV persistent infection is observed in 1%-2% of cattle population (13,18,19,24). In Poland, prevalence of PI animals is similar to other geographic regions of Europe.…”

Understanding the Impact and Control of Bovine Viral Diarrhoea in Cattle Populations

“…In response to the financial impact of both endemic and epidemic BVDV infection, control and eradication schemes are, or have been, in place across much of the cattle-producing world, including all or regions of: Austria, Denmark, Finland, France, Germany, Ireland, Italy, the Netherlands, Norway, Scotland, Slovenia, Sweden, Switzerland, and the United States [1,2,15,20,21,34,35,47,49,56,64,66,72,78]. Details of these schemes are available in the literature.…”

“…In the Netherlands and Switzerland, herd classification was performed on the basis of total herd viral antigen or virus screening using antigen ELISA or reverse transcriptase-polymerase chain reaction (RT-PCR) on ear-notch samples or (pooled or individual) serum, blood or milk samples [49,56].…”