Immunization against anaplasmosis and babesiosis. Part III. Evaluation of immunization under field conditions in the Cauca River Valley.

Bovine anaplasmosis and babesiosis constitute serious constraints to efficient cattle production in Colombia. Nine commercial ranches located in the Cauca River Valley were used to evaluate the applicability, safety and economics of the newly developed immunization technology to control these diseases under actual field conditions using the minimum infective doses techniques. A total of 432 calves, 6--8 months old, of different breeds were used in this experiment. Calves born and raised in nonendemic areas of Valle, vaccinated against anaplasmosis and babesiosis and then moved to the endemic zone had developed a high degree of resistance. None of them died or required treatment after field challenge. In comparison, non-vaccinated controls suffered severe clinical anaplasmosis and babesiosis. Eighteen percent dies and 85% required chemotherapy to survive. Calves born and raised in the endemic zones of Valle and vaccinated did not suffer clinical disease nor require treatment after field challenge. However, non-vaccinated controls had 2% mortality and 60% of them required treatment to survive under the same field conditions. The weight gains favored vaccinated animals. The results of this study indicate significant reductions in deaths and production losses of cattle and the economic benefits to the livestock producers in controlling tick-borne diseases by vaccination.