Genetic characterization and identification of a recent discovered genotype of Theileria orientalis (Piroplasmida: Theileriidae) in water buffaloes (Bubalus bubalis) from the Amazon region, Brazil.

Theileria orientalis is typically considered a benign protozoan parasite of cattle, although certain genotypes can cause significant economic losses in the livestock industry. Despite Brazil harboring the largest buffalo (Bubalus bubalis) herd in the Western Hemisphere, information regarding T. orientalis infections in this species remains scarce. This study aimed to identify and characterize T. orientalis genotypes circulating in water buffaloes from the State of Pará, located in the Amazon region of Brazil. The major piroplasm surface protein (mpsp) gene of T. orientalis was detected by PCR in 39 out of 271 (14.4 %) buffaloes sampled from two farms in Marajó Island (n = 2) and one farm in the mainland (n = 37). Phylogenetic analysis of mpsp gene sequences revealed the presence of three genotypes: two previously described (Types N1 and N2) and one newly identified genotype (provisionally named Type N4). These findings provide the first evidence of T. orientalis genetic diversity in Brazilian buffaloes and highlight the need for further investigations into its epidemiology and potential tick vectors in South America.