Molecular detection of Theileria orientalis genotypes in cattle ticks from Kerala, India

Ticks are obligate haematophagous ectoparasites affecting cattle and act as potential vector for haemoprotozoan diseases like oriental theileriosis caused by Theileria orientalis, leading to substantial economic losses to the dairy farmers. This study aimed to assess the prevalence of tick species and to detect T. orientalis and its genotypes in ticks collected from cattle across north, central and south zones of Kerala, India. A total of 656 ticks were collected and identified as Haemaphysalis bispinosa (40.1 per cent), Rhipicephalus annulatus (32.16 per cent), R. microplus (18.44 per cent) and H. intermedia (9.3 per cent). Haemaphysalis bispinosa was the primary tick species infesting cattle in Kerala. Primers specific to the T. orientalis major piroplasm surface protein (MPSP) gene amplified a 776 bp PCR product in four tick pools of R. annulatus. Genotype-specific PCR targeting MPSP gene confirmed the Buffeli genotype in one pool and mixed genotypes (Chitose and Buffeli) in two pools. One positive tick pool failed to amplify with Chitose, Buffeli or Ikeda genotype specific primers. Furthermore, sequencing and phylogenetic analysis of this pool with T. orientalis MPSP gene sequences revealed close similarity with type 7, belonging to pathogenic Ikeda strain. This study has underscored the importance of circulation of pathogenic genotypes in Kerala. These findings thus highlighted the need for effective tick control strategies to mitigate the spread of T. orientalis, particularly in tropical regions like Kerala. Keywords: Tick-borne pathogens, nucleotide sequence, phylogeny, T. orientalis, R. annulatus