Bovine viral diarrhoea virus ('pestivirus') in Australia: to control or not to control?

BACKGROUND: Acute infection with bovine viral diarrhoea virus (BVDV) usually causes only mild clinical disease in cattle, but infection of animals of breeding age can result in immune suppression (resulting in an increased incidence and severity of secondary disease) and decreased reproductive performance. If infection occurs during pregnancy, the virus may cross the placenta and either cause abortion, establish immunotolerance and persistent infection (PI) in the fetus or cause congenital deformities. These outcomes depend on the stage of pregnancy at the time of infection. INTERNATIONAL PERSPECTIVE: BVDV is recognised as a disease of significant financial impact in a number of countries. As a result, national and regional BVDV control programs are now in place in several regions around the world. In Europe, these programs largely rely on the identification and removal of the PI animals, whereas vaccination has tended to be the chosen method of control in the United States. BVD IN AUSTRALIA: BVDV is endemic in Australian cattle populations, with more than 80% of herds surveyed showing some level of exposure to the pathogen. The cost to the national industry is estimated to be AUD57.9 million annually. This review identifies and discusses the challenges to BVDV control in Australia, including farmer attitudes, herd size, sheep as a potential reservoir host and diagnostic capabilities. We conclude that systematic BVDV control in Australia is, or soon will be, an option; however, detailed cost-benefit analyses will need to be undertaken.