Bovine viral diarrhoea

BVD virus is spread primarily through nose-to-nose contact with infected animals. The majority of BVD infections occur after birth. These infected animals are less productive but are transiently infected and usually recover within two weeks.

Of more concern than transiently infected animals are those that become infected in the womb following viral transmission from the mother. These animals are persistently infected (PI) and continuously shed copious quantities of virus throughout their lives, routinely infecting other members of the herd. Within infected herds, it is estimated that there are 1 or 2 PI animals for every hundred head of cattle. PI animals are particularly costly if they are introduced into immunologically naïve herds that have not previously encountered the BVD virus. Detection of PI animals using specialist diagnostics is therefore essential for effective herd management.

Other sources of infection include semen from infected bulls, while other species including sheep, goats, swine, alpacas, deer, and camelids are also capable of contracting BVD and spreading disease. Typically, infection of non-cattle species species is believed to originate from infected cattle herds. However, wild animals may still be capable of spreading disease between farms or acting as an infective disease reservoir.

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