EPIZOOTIC PROCESS OF BOVINE LEUCOSIS AND PROSPECTS OF INFECTIOUS AGENT DEVASTATION

Abstract

Epizootic process of bovine leucosis has been keeping at invariably high rate for many years. Measures taken against the disease address neither its source nor transmission of the causative agent. Both factors provide for stability of epizootic situation despite of removal of infected animals from herd with the initial signs of hematological stage of the disease. Therefore, existing antiepizootic measures are inadequate to oppose epizootic process of bovine leucosis. Based on own many years experience, review of literature sources, and data on bovine leucosis epidemic process in different regions of the Russian Federation, the author concludes that epizootic process of bovine leucosis consists of a regular transfer of virus from infected cows to the offspring. Initially only a small amount of blood corpuscles are infected with virus. At this stage the disease is undetectable even by means of immunodiffusion test (IDT), and therefore called asymptomatic. As the causative agent expands aggression against the blood corpuscles the disease enters the next stage when it can be detected with IDT. This stage is called serological. Further virus aggression leads to the hematological stage. It progresses with increasing number of infected blood corpuscles and affection of hemopoietic organs, resulting in development of tumors and death. The author suggests IDT-screening of all young heifers at the age of three, six, nine and twelve months with separation of positive test animals and the cow into isolated feeding groups, thus ensuring both improvement of leucosis situation at a farm in 3 - 5 years and devastation of the very causative agent of the infection.