Detection of spotted fever group rickettsiae and Coxiella burnetii in long-tailed ground squirrels (Spermophilus undulatus) and their ectoparasites

Long-tailed ground squirrels (LTGRs, <i>Spermophilus undulatus</i>) are known as reservoirs of multiple arthropod-borne pathogens, such as <i>Yersinia pestis</i> and <i>Bartonella rochalimae</i>. However, data on the prevalence of spotted fever group rickettsiae (SFGR) and <i>Coxiella burnetii</i> in LTGRs and its ectoparasites are limited. In two alpine regions of Xinjiang Uygur Autonomous Region (XUAR, northwestern China), a total of 346 samples were collected from 142 LTGRs, including 142 livers and 204 pooled ectoparasites (<i>Citellophilus tesquorum dzetysuensis</i>: 120 pools of 484 fleas; <i>Frontopsylla elatoides elatoides</i>: 19 pools of 71 fleas; <i>Neopsylla mana</i>: 1 pool of 4 fleas; and <i>Linognathoides urocitelli</i>: 64 pools of 865 lice). From these samples, the DNA was extracted, followed by PCR amplification of different genetic markers. Particularly, genes encoding the outer membrane protein A and B (<i>ompA</i>, <i>ompB</i>), citrate synthase (<i>gltA</i>), and surface cell antigen 1 (<i>sca1</i>) were used to identify the SFGR. Additionly, the capsular outer membrane protein (<i>Com1</i>) gene and insertion sequence (<i>IS1111</i>) genes were used to detect <i>Coxiella</i>. <i>Rickettsia sibirica</i> subsp. <i>sibirica</i>, <i>Rickettsia felis</i>, and <i>C. burnetii</i> were detected in LTGRs, as well as in flea and louse pools. <i>Rickettsia raoultii</i> was found in LTGRs and flea pools. Furthermore, <i>Rickettsia slovaca</i> was also identified in the flea pools. This study provides molecular evidence for the occurrence of SFGR and <i>C. burnetii</i> in LTGRs and their ectoparasites. These findings suggest that <i>R. sibirica</i>, <i>R. slovaca</i>, <i>R. raoultii</i>, <i>R. felis</i> and <i>C. burnetii</i> are transmitted between LTGRs (as potential reservoirs) and their fleas and lice (as potential vectors).