General information

Bovine viral diarrhoea virus is the causative agent of bovine viral diarrhoea/mucosal disease (BVD/MD) in cattle, two diseases that are prevalent worldwide. Sheep, goats, wild ruminants and pigs are also susceptible to the virus. BVD virus has 2 genotypes (BVDV1 and BVDV2) and the biotypes cytopathogenic (cp) and non-cytopathogenic (ncp).

Infection in cattle results in different symptoms depending on the time of infection.

Transient infections (temporary infections of already born animals) are often asymptomatic, but may lead to diarrhoea, fever, cough and erosions of the mucous membrane particularly in calves, and to reduced milk yield, fertility disorders (repeat breeding, abortions) and malformations (e. g. oculo-cerebellar syndrome) in cows. Transiently infected animals temporarily shed the virus to a certain extent (nasal discharge, saliva, faeces, semen).

Persistently infected calves (PI animals) develop during the infection of the mother between the 40th and the 120th day of gestation, because the immune system of the calf does not recognise the virus as “foreign”. PI calves are usually born without abnormalities and shed large quantities of the virus in all secretions and excretions throughout their lives. PI animals are typically seronegative, but can also form antibodies after being infected with a heterologous BVD strain .

If a PI animal is additionally confronted with a cp virus strain through mutation of the prenatally acquired strain or a new, postnatal infection, it will develop a severe and always fatal MD.

In Germany, there is an obligation to notify the authorities upon suspicion.