The protective effect of pretreatment with killed Corynebacterium parvum against acute babesiosis in calves.

Yearling calves were pre-treated intravenously (IV) with a 0.20 mg kg-1 dose of Corynebacterium parvum and challenged after 30 days by IV inoculation of 3 X 10(9) Babesia bigemina. The relatively low 0.20 mg kg-1 dose of C. parvum enhanced resistance as indicated by lower mean Babesia parasitemias and less severe decreases in packed-cell volumes than in non-treated calves, but failed to stimulate a significant (P less than or equal to 0.05) level of protection against B. bigemina challenge.