EN
Thirty seven pregnant heifers were imported from Germany to the Legnica district. Both in imported animals and in local cattle symptoms resembling IBR appeared one week after the introduction of the imported animals. Clinical symptoms were more pronounced in the local cattle. Sera from 35 imported heifers and 69 local cattle were examined against IBR by the SNT and ELISA (Trachitest, Bommeli). Positive results with BHV-1 were obtained with 82.9% sera of imported heifers in ELISA and with 48.6% of sera in the SNT. After 3 months of exposition of local cattle 74% of these animals reacted positively in ELISA and 55% in the SNT. Clinical symptoms and serological data confirmed the fact that BHV-1 was transferred with the imported animals and that this virus caused dangerous effects herds free of BHV-1.