Abstract
Eight hard tick species were identified among a total of 466 samples collected from vegetation in southern Thailand: Dermacentor compactus (n = 150), D. steini (n = 100), D. auratus (n = 85), D. tricuspis (n = 41), Haemaphysalis hystricis (n = 69), H. semermis (n = 3), H. shimoga (n = 2) and Amblyomma testudinarium (n = 16). In 93 ticks from these 8 species, Coxiella bacteria were detected via 16 S rRNA, groEL (60-kDa chaperone heat shock protein B) and rpoB (β subunit of bacterial RNA polymerase) genes. Interestingly, Coxiella burnetii was detected for the first time in H. hystricis and D. steini in Songkhla Province. Coxiella-like endosymbionts (CLEs) were also found in 84 ticks from 7 species, namely, D. compactus, D. auratus, D. tricuspis, H. hystricis, H. semermis, H. shimoga and A. testudinarium. Among these, CLEs associated with D. compactus and H. semermis were reported for the first time in Thailand. Phylogenetic analysis and generation of a haplotype network clearly revealed 2 distinct groups of Coxiella bacteria, namely, C. burnetii and CLEs. The nucleotide alignment of Coxiella 16 S rRNA revealed differences in bases at 3 positions between C. burnetii and CLEs. Thus, these differences could be used as liable molecular markers for discriminating these 2 groups in hard ticks.