Brucella, Coxiella, and Theileria Species DNA in Haemaphysalis qinghaiensis Ticks Collected from Goats and Sheep in Qinghai Province, Northwest China

<i>Haemaphysalis qinghaiensis</i> is an endemic tick species distributed in the western plateau areas of China. Although they are three-host ticks, infesting multiple animals (including humans), the occurrence of various tick-borne agents has barely been investigated. In this study, we collected 136 <i>H. qinghaiensis</i> specimens from sheep and goats in Menyuan County in Qinghai Province, northwest China. The <i>Brucella</i>, <i>Coxiella</i>, and <i>Theileria/Babesia</i> species' DNA were detected by nested or hemi-nested PCR and further identified by amplifying their key genes. <i>Brucella abortus</i> and <i>B. melitensis</i> DNA were detected, with positive rates of 3.68% and 4.41%, respectively. This may be the first report that suggests that <i>H. qinghaiensis</i> harbors <i>Brucella</i> spp., the agents of human brucellosis. The <i>Coxiella</i> endosymbiont of <i>Haemaphysalis qinghaiensis</i>, a non-pathogenic <i>Coxiella,</i> was identified with an extremely high positive rate of 97.06%. In addition, two <i>Theileria</i> species, <i>Theileria luwenshuni</i> (75.00%) and <i>Theileria uilenbergi</i> (16.18%), were detected. Our results suggest the circulation of <i>Brucella</i> spp. and <i>Theileria</i> spp. in goats and sheep in the study area. Whether <i>H. qinghaiensis</i> ticks play a role in the maintenance and transmission of these agents has yet to be determined. Due to their human pathogenicity and their high positive rates in ticks, surveillance in local populations with relative symptoms is necessary.