Bovine Viral Diarrhoea Virus Eradication Research Articles

BVD Decision / Management Guidelines for Beef Veterinarians

Characteristics of bovine viral diarrhoea virus (BVDV), such as genetic diversity and ability to induce a persistently infected (PI) carrier state, make its control a challenge. The Academy of Veterinary Consultants (AVC) drafted and approved a position statement in 2001 resolving to adopt measures to control and target eventual eradication of BVDV from North America. As part of this effort, the AVC formed an ad hoc committee to develop a document to provide guidelines for BVDV control based on the best current information. The final document was approved by the AVC in 2003, and provides management guidelines for control of BVD in beef cow-calf herds, stocker operations and feedlots.

Principles for eradication of bovine viral diarrhoea virus (BVDV) infections in cattle populations

Systematic eradication of BVDV without vaccination started in Scandinavia in 1993. In principle, the schemes include; (1) identification of non-infected and infected herds using different combinations of serological herd tests such as bulk milk tests and spot tests (sample of animals in a certain age), (2) monitoring/certification of non-infected herds by repeated sampling, applying one of the above-mentioned methods and (3) virus clearance in infected herds aimed at removing persistently infected (PI) animals in a cost- and time-efficient manner. In the virus clearance protocol described, an initial test is performed on all animals with subsequent follow-up of calves born as well as of dams seronegative in the initial test. It is generally recommended to perform an initial antibody test on all samples. This should be done not only to screen for seronegative animals on which virus isolation should be attempted (i.e. possible PI animals), but more in order to identify non-immune animals in reproductive age, that is, the key animals in herd-level persistence of infection. In Sweden, a common finding has been self-clearance, where the infection ceases without any other intervention than controlled introduction of new animals. Other epidemiological observations concern the course of events following virus introduction. Important risk factors for spreading BVDV are discussed, where livestock trade is perceived as the most central to control. Live vaccines, imported semen and embryos constitute special hazards, since they may act as vehicles for the introduction of new BVDV strains. The importance of making farmers aware of herd biosecurity and their own responsibility for it is stressed, and in order to maintain a favourable situation after a scheme has been concluded, effort must be put into establishing such a persisting attitude in the farming community.