Molecular characterization of Trypanosoma evansi isolates from water buffaloes (Bubalus bubalis) in the Philippines.

Trypanosoma evansi infection in the Philippines is frequently reported to affect the country's livestock, particularly, the buffaloes. To assess the prevalence and intraspecific diversity of T. evansi in the country, blood samples from water buffaloes in different geographical regions were collected during an outbreak. T. evansi was detected in all 79 animals tested using PCR targeting the RoTat 1.2 VSG gene. Sequencing of the rDNA complete internal transcribed spacer (ITS) region including the 5.8S subunit showed high similarity (99-100%) between Philippine isolates and known T. evansi isolates in Genbank. Tree construction based on the same region confirmed the close relationship between Philippine and reported Thai isolates as compared to Egyptian isolates separated by relatively small genetic distances, 47 polymorphisms, despite the clustering in four branches. Overall, the results of this study prove genetic diversity within T. evansi species despite previous reports on limited heterogeneity among isolates worldwide.