Isolation of Trypanosoma (Megatrypanum) theileri from dairy cattle in Taiwan.

Although Trypanosoma (Megatrypanum) theileri, a blood parasite of bovid species, is spread widely throughout the world, it has never been reported in Taiwan. When an anti-coagulated blood sample from febrile dairy cattle was directly smeared, no parasite was observed. However, a highly distinctive morphological feature of trypanosome appeared in baby hamster kidney (BHK) cell culture inoculated with non-thrown blood buffy coat. The different stages and typical ultrastructures of trypanosome were observed in our isolate. The isolate was subsequently identified as T. theileri by species-specific PCR assay (Tth625), 18S rDNA sequencing alignment and internal transcribed spacer of ribosomal genes (ITS) as a marker for molecular phylogenetic analysis. The first T. theileri isolate in Taiwan (TWTth1) could be periodically passaged in BHK cell culture for more than one year and retained good re-cryopreservation viability. The BHK culture method would be excellent for diagnostic isolation and maintenance long-term development of this parasite.