Molecular detection and characterisation of Babesia and Theileria in Australian hard ticks

Babesia and Theileria are intraerythrocytic protozoans of the phylum Apicomplexa. These species are capable of infecting wild and domestic animals and have historically caused great economic loss in the agricultural industry. In recent years human babesiosis has been deemed an emerging zoonosis in North America, Europe and Asia. The first locally acquired case of babesiosis in Australia, caused by Babesia microti, was reported in March 2012. A number of native Babesia and Theileria species have been identified in Australian marsupials, however their associated tick vectors and threat to human health is unknown. In the present study DNA was extracted from 1154 ticks collected from across Australia. PCR was used to amplify a Babesia and Theileria-specific partial region of the 18S ribosomal RNA gene. Positive samples were sequenced and phylogenetic analysis was performed. Twenty-nine sequences were obtained from ticks belonging to the genera Ixodes, Haemaphysalis and Bothriocroton. The sequences were closely related to Babesia macropus, and Theileria recently identified in marsupials and monotremes. Bayesian inference and maximum likelihood methods showed that Australian Babesia and Theileria species form monophyletic groups.