Abstract:
Haemoparasites have been a source of economic and research interest for animal managers for some time. Of these, the role played by the Apicomplexan Babesia and Theileria species in both domesticated animals and wildlife has been of major importance, as has been the role that tick vectors play in their life cycle and the routes of transmission to domesticated animals. Babesia and Theileria species differ in morphology, life cycle, epidemiology and the clinical signs produced in host species. Both genera are obligate intracellular parasites. A major difference between the two genera is the fact that Theileria species undergo schizogony and transstadial transmission in the tick vector, while Babesia species do not undergo schizogony and have a transovarial mode of transmission in the tick vector. Investigating the role that specific probes, suggesting the presence of a novel species or variant of a species. No Ehrlichia and/or Anaplasma species could be detected.
The parasite 18S rRNA gene of five spotted hyaena samples was subsequently amplified, cloned and the recombinants sequenced. Homologous sequence searches of databases that were performed using the BLASTn package indicated that the obtained sequences were most closely related (98 – 99% identity) to B. lengau, previously identified in cheetah in South Africa. The observed sequence similarities were subsequently confirmed by phylogenetic analyses which showed that the obtained hyaena sequences formed a monophyletic group with B. lengau, B. conradae and sequences previously isolated from humans and wildlife in the western USA. Within the B. lengau clade, the obtained sequences and the published B. lengau sequences grouped into four distinct groups, of which groups I, II and III each represented a novel B. lengau genotype. It remains difficult to establish how much 18S rRNA gene sequence variation must exist for the source organism to be considered a different species or to be considered merely a variant and/or genotype of a species. Based on this, as well as the fact that we do not have any data on the morphology of the parasites, their possible vectors or their role in clinical disease, we suggest that these genotypes cannot be classified as new Babesia species, but rather as variants of B. lengau.
The study confirms that hyaena are susceptible to infection by a Babesia sp similar to B. lengau, but also demonstrates that they are not clinically affected by the infection. Their role as carriers of this organism and their ability to carry this infection over to other species still needs elucidation.
