Present Status of and Trends in Tuberculosis and Brucellosis in Cattle

Tuberculosis and brucellosis have been greatly reduced in the cattle population. The reduction has led to complacency in the eradication effort. In each of these cooperative State-Federal Eradication Programs there have been modifications of program procedures as husbandry practices changed. Surveillance at slaughter is currently the basis for location of herds affected with either of these diseases. A lesion resembling a tubercle found by the meat inspector on postmortem examination starts a tracing procedure leading to a tuberculin test of the herd from which the lesioned animal originated. A blood sample for brucellosis is also collected from adult cattle at slaughter and sent to the laboratory. Any reactors likewise are traced and herds tested. Effectiveness of the surveillance is dependent on accurate identification of slaughter animals. This has improved, but needs further improvement. Dairy herds benefit from additional surveillance through the milk ring test which has proven to be very effective when conducted three or four times each year on bulk milk samples collected at dairy plants. Use of Brucella abortus strain 19 vaccine decreased with reduction of Federal funds supporting vaccine purchase and administration. Vaccination is currently being encouraged especially for cattle moving into the more heavily infected areas in the South. New immunizing agents and diagnostic procedures are being studied for brucellosis. The comparative cervical test is being widely used to eliminate problems relating to sensitivity to mycobacteria other than those causing tuberculosis in cattle.