The characteristic of leucosis of cattle is provided in work, the epizootic situation on leucosis in Kazakhstan and rural districts of Kostanay region is covered, results of comparative diagnostic value of reaction of immunodiffusion (RID) and the immunofermental analysis (IFA) are shown, options of preventive and improving actions are proved. Options about possibility of infection of the person of VL cattle and its consequence are discussed. The question that RID-positive animals, lifelong carriers of an oncovirus at all stages of an illness and are obvious sources etiologic agent of leucosis: is considered. The "Veterinary Rules about Urgent Measures of Prevention and Improvement of Cattle from Leucosis in Breeding Farms and Agricultural Formations of All Forms of Ownership" project is developed. It is established that full delivery of RID-positive animals without overexposure, in process of their identification, is the most expedient, economically justified and most perspective method.
