NATURAL TRANSMISSION OF BOVINE LEUKEMIA-VIRUS IN DAIRY AND BEEF-CATTLE

Many potential routes of bovine leukemia virus (BLV) transmission are reviewed in this article. Vertical transmission, in utero, or through colostrum and milk, accounts for a relatively small proportion of infe ctions. Iatrogenic horizontal transmission, through procedures permitt ing the transfer of blood between cattle, has been shown to be a major route of transmission in most settings. Contact transmission stems fr om a mixture of natural sources of blood, exudates, and tissues that e nter the body through mucosal surfaces or broken skin. Careful analysi s of management procedures and environmental conditions present in ind ividual dairy and beef herds affords the greatest opportunity to devel op effective BLV prevention programs.