Abstract:
Calves infected with Babesia bovis or Babesia bigemina between 3 and 9 months of age can develop immunity without showing overt clinical signs. This transient immunity is not dependent on maternal immunity. After 9 months of age, they are fully susceptible to challenge. Dairy calves between 2 and 3 months of age were vaccinated with B. bigemina and B. bovis live frozen vaccines (Onderstepoort Biological Products®). Two months after vaccination, 90% of calves were serologically positive on IFA test to B. bigemina, and 70% were serologically positive to B. bovis. At this age, only 17% of the control group had seroconverted to B. bigemina and none of the calves had seroconverted to B. bovis. All experimental calves maintained positive serological status to both B. bovis</i. and B. bigemina for at least 5 months after vaccination. It is sound practice to vaccinate dairy calves against babesiosis at 2–3 months of age. Endemic stability is achieved before the period of natural resistance wanes. Copyright
