Molecular Detection of SFGR in Ticks Collected from Yaks in Jiulong County of Sichuan Province, China

This study investigated tick species and spotted fever group rickettsiae (SFGR) infection rates in ticks from yaks in Jiulong County, Sichuan Province, China. Firstly, ticks collected from yaks were meticulously classified through morphological identification. Subsequently, the total DNA of ticks was extracted, and specific partial sequences of their <i>ITS-2</i> region, as well as the <i>ompA</i> and <i>ompB</i> genes of SFGR, were amplified using PCR. The positive PCR products were sequenced and compared thoroughly against the NCBI database. A phylogenetic analysis was conducted for <i>ITS-2</i>, <i>ompA</i>, and <i>ompB</i> to determine the species of tick and the SFGR. The results revealed that a total of 585 ticks were collected, with the most abundant species being <i>R. microplus</i>, which accounted for 52.65% (308/585) of the total and was followed by <i>I. ovatus</i> (32.99%, 193/585), <i>I. acutitarsus</i> (8.89%, 52/585), and <i>D. everestianus</i> (5.50%, 32/585). Furthermore, SFGR was detected in 63.93% (374/585) of the ticks. Notably, the infection rate of SFGR in semi-agricultural and pastoral areas was significantly higher at 70.60%, compared to 45.10% in pastoral areas (<i>p</i> < 0.01). Overall, this study marks the first investigation into the prevalence of SFGR in Jiulong County and highlights the high infection rate of SFGR in ticks, with <i>R. raoultii</i> being the predominant species.