Transmission of BLV between infected cows and their calves during gestation periparturient period: a Pilotstudy in Chile, Xth Region.

Abstract

Summary Bovine Leukemia Virus (BLV) is a retrovirus that causes economic looses in dairy herds in Chile. Infection is mostly due to blood related proceedings, where infected B-lymphocytes can transfer form one cow to another. Less important, but also less understand is the possibility of a very early infection during gestation and in the first days of life of a newborn calf. The objective of this study was to estimate the infection rate of newborn calves in highly infected herds in the Xth region of Chile. From 61 newborn calves and 55 of their dams; blood samples were collected and tested with a commercial enzyme-linked-immunosorbent assay (ELISA). From this, 57,7 % positive calves and 45 % of the dams tested positive. The correlation (Pearson-correlation) between them was .866 (sign. <.001), including the observance of interfering maternal antibodies. To exclude the influence of maternal antibodies 29 selected blood samples were retested by PCR. 15.4% (n=4) tested positive, knowing that all their dams tested positive too. Due to less data and many interfering factors in management and execution of this research it isn’t possible to deduce any reliable consequences for the level of infection in newborn calves.