Bovine babesiosis: a review of recent advances

Bovine babesiosis, caused by parasites of the genus Babesia, is one of the world's most severe tick-borne problems of cattle in temperate to tropical areas. In the Americas Babesia bovis and B. bigemina are the causative agents, with the former considered to produce the greatest economic impact. The great complexity of the relationships causal agent-vector-host has severely hindered the efforts towards the production of a safe, long-lasting, solid-protection inducing vaccine. Recent important contributions that have encouraged the study of these agents include the development of in vitro cultivation systems, procedures for the isolation of single infected-erythrocytes, density gradient-based centrifugation systems for the isolation and concentration of both infected erythrocytes and merozoites, isozyme detection and differentiation systems that help discriminate between parasite species, and development of DNA-based diagnostics and characterization protocols. Currently, the study of the cellular immune responses against these parasites is taking new endeavors in order to discern the relationship between B cells, T cells, macrophages and their products and parasites leading to the establishment of solid, long-lasting protection. In an attempt to design a rational vaccine, T cell lines and clones are being established, and phagocytosis of infected erythrocytes and their antigens studied to try to pinpoint relevant epitopes.