Serum carboxypeptidase B levels during acute and mild Babesia bovis and acute Babesia bigemina infections of cattle.

Serum carboxypeptidase B (SCPB) levels were measured in splenectomised calves and in non-splenectomised cattle infected with three virulent and one avirulent strains of Babesia bovis, and in splenectomised calves infected with virulent Babesia bigemina parasites. SCPB levels commenced falling three days post-infection in animals infected with virulent B. bovis strains and fell significanttly terminally. In animals infected with the avirulent B. bovis strain, the SCPB levels were not significantly altered. Animals infected with B. bigemina had no significant changes in their SCPB levels. Fatal infections were uniformly observed in animals with virulent B. bovis, but only two of six animals infected with B. bigemina and none infected with avirulent B. bovis, died.