How To Systematically Manage BVDV
Your focus needs to be on PI animals!
PI animals are born from other PI’s (approximately 10%) or from animals which were transiently infected with BVDV (approximately 90%).
PI animals propogate transient infections in other animals. However, unlike other diseases, transient infections normally do not propagate the disease. Prior exposure or vaccination to BVDV prior to being exposed to a PI provides a level of protection to the individual animal and herd.
The goals of systemic BVDV control are straightforward:
1
Identify at risk management groups and provide them with immunity
3
Ensure annually that each new replacement heifer management group is both PI free and reasonably immune prior to their first joining
2
Ensure no adult PI animals exist within any of the pre-existing adult management groups
4
Maintain simple biosecurity procedures
There are 3 tools for managing BVDV
Blood Testing (Antibody) Exposure Test
The IDEXX BVDV Total Ab Test is an enzyme immunoassay (ELISA) designed to detect BVDV antibodies in serum, plasma and milk samples. A positive test result indicates prior exposure (or vaccination) to BVDV.
Highly immune animals do not benefit from vaccination, and could harbour one or more PI animals, warranting ear notch testing.
Groups without evidence of exposure to the virus are unlikely to harbour a PI, but would benefit from the protection conferred from vaccination.
Ear Notch Testing (Antigen) Finding the PI
Ear Notch testing using the IDEXX BVDV Ag Serum Plus test is the easiest and most widely used test globally to reliably detect PI animals.
Vaccination
Currently, there is only one commercially available vaccine for BVDV in Australia. The vaccine requires 2 preliminary doses from between 4 weeks to 6 months apart, followed by annual boosters.
Some vaccinated animals may still produce PI calves should they be exposed during pregnancy and vaccinating PI animals is ineffective.