Genetic Characterization of Dermacentor sp. and Associated Anaplasma bovis, Infesting Small Ruminants in Pakistan

Ticks are hematophagous ectoparasites and important vectors of pathogens affecting animal and human health. Species of the genus Dermacentor infest a wide range of mammalian hosts, including small ruminants; however, information on their occurrence and genetic diversity in Pakistan remains limited. The present study aimed to morphologically and molecularly characterize Dermacentor ticks collected from small ruminants in Balochistan, Pakistan, and to screen them for Anaplasma species. A total of 35 ticks were collected and morphologically identified as Dermacentor sp. Female ticks showed an oval, brownish-red body with an ornamented scutum, well-developed spiracles, and distinct coxal spurs, while male ticks exhibited an oval body with a strongly ornamented scutum having distinct grooves and punctations, with festoons and lateral eyes at the level of coxa II. Genomic DNA was extracted and subjected to PCR amplification of mitochondrial 16S rDNA and cox1 genes for tick characterization, while Anaplasma spp. were screened using 16S rDNA. BLAST analysis of the obtained 16S rDNA and cox1 sequences revealed the highest similarity (98.42% and 97.45%, respectively) to Dermacentor pavlovskyi reported from China. Phylogenetic analyses based on both markers placed the Pakistani Dermacentor sequences in a clade closely related to D. pavlovskyi. Furthermore, Anaplasma 16S rDNA sequences detected in Dermacentor ticks showed 100% identity with Anaplasma bovis and clustered with corresponding reference sequences in the phylogenetic tree. The findings provide molecular evidence of a Dermacentor lineage closely related to D. pavlovskyi and the presence of A. bovis DNA in Dermacentor ticks from Balochistan, highlighting the need for broader sampling and additional genetic markers to clarify the taxonomic status, distribution, and pathogen associations of Dermacentor ticks in Pakistan.

Keywords: Dermacentor sp.; Anaplasma bovis; tick; Pakistan