Bovine anaplasmosis: susceptibility of seronegative cows from an infected herd to experimental infection with Anaplasma marginale.
Adult cows from an Anaplasma marginale-infected herd that were negative to the A marginale rapid card agglutination (RCA) and complement fixation (CF) tests for 1 to 4 years developed acute anaplasmosis after inoculation with 0.5 ml of blood from an A marginale carrier cow. The test cattle were as susceptible as the control cattle of similar ages. Also, 2 cows that had seroconverted from RCA/CF-positive to RCA/CF-negative status naturally were fully susceptible to anaplasmosis when they were experimentally infected. Results of the study indicated that indigenous seronegative cattle in anaplasmosis-enzootic regions probably do not have acquired or natural immunity to A marginale infection.
D000372:Agglutination Tests / Q000662:veterinary; D000712:Anaplasmosis / Q000276:immunology* / Q000635:transmission; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000276:immunology* / Q000382:microbiology / Q000635:transmission; D003168:Complement Fixation Tests / Q000662:veterinary