ATTEMPTS AT PREVENTING FURTHER SPREAD OF BOVINE VIRUS DIARRHEA VIRUS (BVDV) INFECTION IN 5 DANISH DAIRY HERDS IN WHICH BVDV HAD BEEN ISOLATED

In 5 herds in which bovine virus diarrhoea virus (BVDV) had been isola ted, all animals were bled for virological and serological examination . After the herd blood test, follow up blood tests were made on calves born up to 6 months later in 1 herd, 9 months later in 1 herd and up to 12 months later in 3 herds. Persistently infected animals (PI anima ls) were removed and after a time period a small herd sample of 10 ani mals that were born after removal of the PI animals were examined for BVDV antibodies. At the herd blood test a total of 21 PI animals were detected. During the follow up period another 25 PI animals were born. Among animals in the small herd samples collected after removal of th e PI animals, antibody positive animals were found in the 2 herds with the shortest follow up period. In the 3 herds with a 1 year follow up period there were no antibody carriers in the herd sample.