Molecular detection of Bartonella in ixodid ticks and plateau pika (Ochotona curzoniae) in Shiqu County, China

Abstract Background: Bartonella bacteria have been associated with an increasingly wide range of human and animal diseases. They were identified as being globally dispersed as emerging pathogens. Ticks and small rodents are known as hosts of human and animal bartonellosis. They play a significant role in the preservation and circulation of bartonellae in nature. This study investigates the occurrence of Bartonella spp. in ticks and plateau pika in Shiqu county which is located on the Eastern Qinghai-Tibetan plateau in China. Shiqu county is spread over approximately 26,000 square kilometers, with an average altitude of above 4,200 meters and vast area of pastureland.Results: A total of 818 ticks (Dermacentor everestianus, 79.0%, 646/818; Haemphysalis qinghaiensis, 21.0%, 172/818) were collected in 4 villages of Shiqu county. Only Bartonella melophagi was detected in tick samples with a total prevalence of 30.1% (246/818). The infection rates of Bartonella spp. in ticks from Arizha, Maga, Derongma, and Changxgma were 4.8%, 76.8%, 12.5%, and 18.0% respectively. The infection rate of Bartonella spp. in Maga was higher (p< 0.01) than in other villages. Regarding plateau pika, the total infection rate of Bartonella spp was 24.1%, with 20.8% (15/72), 30.9% (25/81), 13.8% (9/65), and 29.4% (20/68) in Arizha, Maga, Derongma, and Changxgma respectively. Finally, B. queenslandensis, B. grahamii, and two unvalidated Bartonella species were detected. No significant difference was observed (p> 0.05) in the infection rates between these study sites.Conclusion: To date, only D. everestianus and H. qinghaiensis were found in Shiqu county with high infection of Bartonella spp. in the ticks and plateau pika. The threats of Bartonella species to the public health should be closely monitored.