Field evaluation of an exoantigen-containing Babesia vaccine in Venezuela

Abstract

Bovine babesiosis is endemic in Venezuela, causing significant losses in highly susceptible imported cattle. Current immunoprophylactic methods include the less desirable use of live parasites. Inactivated vaccines derived from exoantigen-containing supernatant fluids of in vitro Babesia bovis and B. bigemina cultures have been developed and constitute a major improvement in vaccine safety, stability and ease of handling. Vaccination trials conducted under field conditions provide the final evaluation of a culture-derived B. bovis-B. bigemina vaccine. During a 5-year period, approximately 8,000 cattle were vaccinated and 16 clinical trials carried out in 7 states of Venezuela. Clinical, serologic and parasitologic data were collected monthly from 10% of the animals over a 2-year period. Data were also collected from a similar number of nonvaccinated control cattle. Analysis of results from these trials demonstrated a reduction in the incidence of clinical disease among vaccinated animals and complete protection against mortality caused by babesiosis. Vaccine efficacy was measured calculating the incidence rates of disease and mortality among vaccinated and nonvaccinated cattle. Use of this inactivated vaccine offers the best combination of safety, potency and efficacy for the effective immunoprophylactic control of bovine babesiosis.

Babesiosis of cattle

“…The inoculation of cattle with killed parasites mixed with Freund's complete adjuvant partially protected against homologous challenge. Cell culture-derived exoantigens of B. bovis and B. bigemina have been extensively studied and proposed for use as vaccine in developing countries with reported promising results (Montenegro-James, 1989 ;Montenegro-James et al 1992 ;Patarroyo et al 1995). Other studies have shown the level and duration of protection conferred by these antigens against heterologous challenge was considerably less than those of live vaccines (Timms, Stewart & Dalgliesh, 1983 b).…”

Vaccination against Bovine Babesiosis

“…Given that adjuvant, crude inactivated vaccines prepared from the blood of calves infected with B. bovis, B. bigemia , and B. divergens , or from cell culture‐derived babesial exoantigens have been used, mainly, on an experimental basis. 20‐23 The degree and duration of immunity against heterologous challenge has not been well documented but it appears to be adequate to prevent mortality in most cases, although less than those of live vaccines. 13 These vaccines have, with the exception of a B. divergens vaccine in Austria, 20 not translated into viable, available options for control.…”