Changes

Control of BVD is practiced to a greater extent than treatment. The aim is eradication on individual farms but some countries, for example in Scandinavia, have achieved national eradication. There are several elements to control, including effective biosecurity, elimination of persistently infected animals, and vaccination strategies³⁹.

Control of BVD is practiced to a greater extent than treatment. The aim is eradication on individual farms but some countries, for example in Scandinavia, have achieved national eradication. There are several elements to control, including effective biosecurity, elimination of persistently infected animals, and vaccination strategies³⁹.

Biosecurity measures can include the usually hygiene precautions taken on farms, by visitors and during veterinary attention, as well as scrutiny of bought-in livestock and biologicals. Replacement cattle should be tested for persistent infection and quarantined on-farm in case of acute infections before entering the herd. If the resident herd is BVD-vaccinated, new animals should be brought up to date before joining the cohort. Embryo donors should be tested for persistent infection before transfer occurs, and purchase of in-calf heifers should be avoided as their offspring may be persistently infected. BVDV is shed in semen, so breeding bulls and semen for artificial insemination should be tested before coming into contact with cows.

Biosecurity measures can include the usual hygiene precautions taken on farms, by visitors and during veterinary attention, as well as scrutiny of bought-in livestock and biologicals. Replacement cattle should be tested for persistent infection and quarantined on-farm in case of acute infections before entering the herd. If the resident herd is BVD-vaccinated, new animals should be brought up to date before joining the cohort. Embryo donors should be tested for persistent infection before transfer occurs, and purchase of in-calf heifers should be avoided as their offspring may be persistently infected. BVDV is shed in semen, so breeding bulls and semen for artificial insemination should be tested before coming into contact with cows.

A protocol for screening cattle herds for persistent infection should be implemented. Testing can be achieved by virus isolation or antigen-capture ELISA from serum or buffy coat cells, or by antigen detection in skin biopsies. The selected programme should be designed aroung the type and size of herd, financial limitations and the techniques available at the chosen diagnostic laboratory. Once identified, persistenly infected animals should be culled as soon as possible.

A protocol for screening cattle herds for persistent infection should be implemented. Testing can be achieved by virus isolation or antigen-capture ELISA from serum or buffy coat cells, or by antigen detection in skin biopsies. The selected programme should be designed aroung the type and size of herd, financial limitations and the techniques available at the chosen diagnostic laboratory. Once identified, persistenly infected animals should be culled as soon as possible.

Both modified live and beta-propiolactone inactivated BVDV vaccines are available for used. Although cross-protection between strains and genotypes is generally good, antigenic diversity among challenge viruses may affect the efficacy of a given vaccine. Because BVDV is tropic for the foetus, and so modified live vaccines should not be used in pregnant animals. The virus is also immunosuppressive and so vaccination of animals showing signs of disease is not recommended. Maternally-derived antibody wanes at 3-6 months of age, and so to ensure that vaccination induces a protective immune response animals should be vaccinated (or re-vaccinated) after this age.

Both modified live and beta-propiolactone inactivated BVDV vaccines are available for used. Although cross-protection between strains and genotypes is generally good, antigenic diversity among challenge viruses may affect the efficacy of a given vaccine. Because BVDV is tropic for the foetus, modified live vaccines should not be used in pregnant animals. The virus is also immunosuppressive and so vaccination of animals showing signs of disease is not recommended. Maternally-derived antibody wanes at 3-6 months of age, and so to ensure that vaccination induces a protective immune response animals should be vaccinated (or re-vaccinated) after this age.

==Links==

==Links==