Development of a Babesia bovis live attenuated vaccine
Alonso, M.; Blandino, T.; Mendoza, E.; Savon, L.; Camacho, M.
Archives of Medical Research 25(2): 273-277
1994
ISSN/ISBN: 0188-4409 PMID: 7919825 Document Number: 435083
A control programme based on immunization of cattle with an attenuated strain of Babesia bovis was developed. For this purpose, a virulent B. bovis strain was isolated and then attenuated by passaging through splenectomized calves, biological characteristics, proteolytic activity and vector transmissibility were studied. The protection conferred by the vaccine was measured by vaccinating cattle which were then challenged with a heterologous strain. In order to assess postvaccination accident risks, 2603 cattle were vaccinated and those showing clinical signs of babesiosis were treated. A study of cost-benefit was performed in a herd of 591 animals where frequent outbreaks of babesiosis occurred, 183 animals were vaccinated; prevalence and clinical case incidence in vaccinated and nonvaccinated animals were determined. Vaccinated animals survived challenge whereas 2 control animals died. In 2% of the vaccinated animals less than 6 months of age, post-vaccination accidents occurred, whereas in older animals this index was higher. The cost-benefit study showed a rate of approximately $10 pesos (national currency) for each peso invested due to the high mortality caused by the parasite. It is concluded that until an effective, killed vaccine is available, vaccination with live vaccines is advantageous in the prevention of bovine babesiosis.