The northwestern region of China, known as the Qinghai–Tibet Plateau Area (QTPA), is characterized by unique climate conditions that support the breeding of various highly-adapted livestock species. Tick vectors play a significant role in transmitting Babesia and Theileria species, posing serious risks to animal health as well as the economy of animal husbandry in QTPA. A total of 366 blood samples were collected from Tibetan sheep (n = 51), goats (n = 67), yaks (n = 43), cattle (n = 49), Bactrian camels (n = 50), horses (n = 65), and donkeys (n = 40). These samples were examined using conventional and nested PCR techniques to detect Theileria and Babesia species. The overall infection rates were 0.3% (1/366) for Babesia spp. and 38.2% (140/366) for Theileria spp. Notably, neither Babesia nor Theileria species were detected in donkeys and yaks. The infection rates of Babesia and Theileria species among animals in different prefectures were significantly different (p < 0.05). Furthermore, Babesia bovis, B. bigemina, B. caballi, and B. ovis were not detected in the current study. To our knowledge, this is the first documented detection of Theileria luwenshuni infection in Bactrian camels and goats, as well as T. sinesis in cattle and T. equi in horses on the Qinghai plateau. These novel findings shed light on the distribution of Babesia and Theileria species among livestock species in QTPA.

The Qinghai-Tibetan Plateau area (QTPA) features a unique environment that has witnessed the selective breeding of diverse breeds of domestic livestock, exhibiting remarkable adaptability. Nevertheless, Anaplasma spp., Rickettsia spp., Coxiella spp., and Borrelia spp. represent tick-borne bacterial pathogens that pose a global threat and have substantial impacts on both human and animal health, as well as on the economy of animal husbandry within the Qinghai-Tibetan plateau area. In this study, a total of 428 samples were systematically collected from 20 distinct areas within the Qinghai plateau. The samples included 62 ticks and 366 blood samples obtained from diverse animal species, to detect the presence of Anaplasma spp., Rickettsia spp., Coxiella spp., and Borrelia spp. The prevalence of infection in this study was determined as follows: Anaplasma bovis accounted for 16.4% (70/428), A. capra for 4.7% (20/428), A. ovis for 5.8% (25/428), Borrelia burgdorferi sensu lato for 6.3% (27/428), Coxiella burnetii for 0.7% (3/428), and Rickettsia spp. for 0.5% (2/428). Notably, no cases of A. marginale and A. phagocytophilum infections were observed in this study. The findings revealed an elevated presence of these pathogens in Tibetan sheep and goats, with no infections detected in yaks, Bactrian camels, donkeys, and horses. To the best of our knowledge, this study represents the first investigation of tick-borne bacterial pathogens infecting goats, cattle, horses, and donkeys within the Qinghai plateau of the Qinghai-Tibetan Plateau Area. Consequently, our findings contribute valuable insights into the distribution and genetic diversity of Anaplasma spp., Rickettsia spp., Coxiella spp., and Borrelia spp. within China.

As a core pastoral region of the Qinghai–Tibet Plateau, Qinghai Province faces substantial threats to livestock production from tick-borne diseases. This study aimed to investigate the prevalence of six bacterial pathogens in dominant tick species from Qinghai Province, to provide baseline epidemiological data for local tick-borne disease surveillance. A total of 1025 questing ticks were collected from key pastoral regions of Qinghai Province during April to May in 2024 and 2025. All ticks were morphologically identified as belonging to 1 family (Ixodidae), 2 genera, and 4 species. Dermacentor nuttalli was the dominant species with a relative dominance of 66.83% (685/1025, 95% CI: 63.92–69.61%), followed by Haemaphysalis qinghaiensis at 30.83% (316/1025, 95% CI: 28.11–33.69%), Dermacentor silvarum at 1.95% (20/1025, 95% CI: 1.27–2.98%), and Dermacentor niveus at 0.39% (4/1025, 95% CI: 0.15–1.01%). PCR detection was performed for six target pathogens, with an overall Brucella spp. DNA detection rate of 0.78% (8/1025, 95% CI: 0.40–1.53%) and an overall Rickettsia spp. detection rate of 16.29% (167/1025, 95% CI: 14.16–18.67%). Statistical analysis showed that the prevalence of Brucella spp. and Rickettsia spp. differed significantly between the two dominant tick species (Fisher’s exact test/χ² test, all p < 0.001). No Brucella or Rickettsia pathogens were detected in D. silvarum and D. niveus. Notably, detection of Brucella spp. DNA does not confirm the presence of viable bacteria or tick vector competence. This study fills the regional data gap of tick-borne pathogens in Qinghai, and provides reference for the prevention and control of local tick-borne zoonotic diseases.

Tick-borne zoonotic pathogens, including Rickettsia, Anaplasma, Ehrlichia, and Babesia spp., pose increasing risks to human and animal health. This study investigated tick species composition and associated zoonotic pathogens across high-(1500–3000 m) and very high-altitude (>3000–5500 m) zones of the Qinghai-Tibetan Plateau area (QTPA). A total of 1025 questing ticks were collected from 11 counties and identified as Haemaphysalis qinghaiensis (n = 316), Dermacentor nuttalli (n = 685), D. silvarum (n = 20), and D. niveus (n = 4). Tick composition showed clear zonal variation. In the high-altitude zone, all four species were present, with H. qinghaiensis as the dominant species. In contrast, only Dermacentor spp. were detected in the very high-altitude zone, where D. nuttalli predominated. PCR and sequence analyses detected DNA of multiple pathogens in 137/1025 (13.4%) ticks. Rickettsia was most prevalent (11.4%), followed by Anaplasmataceae (2.2%) and Babesia (0.2%). In the high-altitude zone, H. qinghaiensis harbored R. raoultii, R. slovaca, Anaplasma phagocytophilum, A. bovis, uncultured Rickettsia, Anaplasma, and Ehrlichia spp., and a Babesia motasi-like organism. In contrast, in the very high-altitude zone, D. nuttalli mainly carried R. raoultii, R. slovaca, A. phagocytophilum, A. ovis, and uncultured Rickettsia and Ehrlichia spp. In conclusion, tick species composition and associated pathogens varied between the altitude zones in QTPA. In particular, the predominance of human-biting D. nuttalli in the very high-altitude zone, together with detection of zoonotic agents, highlights the public health relevance of tick-borne infections in this region. Additional studies are essential to establish vector competence or transmission.

Cervids harbor several Babesia taxa, but their potential to infect cattle remains poorly understood. The present study detected Babesia taxa in wild sika deer in Hokkaido, Japan, and subsequently examined questing ticks collected from cattle pastures and sympatric grazing cattle for their presence. The initial screening of 285 sika deer blood DNA samples using a PCR assay targeting the 18S rRNA of Babesia spp., followed by sequencing, identified two previously reported Babesia taxa: one closely related to Babesia divergens and designated Babesia sp. Sika 1, and another unclassified Babesia taxon designated Babesia sp. Sika 2. A duplex PCR assay based on the obtained 18S rRNA sequences was then used to detect these two taxa in 285 sika deer, 671 questing ticks, and 767 cattle. Babesia sp. Sika 1 was detected in 86/285 (30.2%) deer and 7/367 (1.9%) Ixodes persulcatus ticks, whereas Babesia sp. Sika 2 was detected in 4/285 (1.4%) deer but not in the examined ticks. Neither taxon was detected in any cattle samples. Phylogenetic analyses placed Babesia sp. Sika 1 in a distinct lineage from B. divergens, supporting its recognition as a distinct Babesia taxon. Similarly, Babesia sp. Sika 2 formed a distinct phylogenetic clade in the 18S rRNA analysis. Despite opportunities for exposure through shared pasture environments and I. persulcatus feeding on both hosts, neither taxon was detected in the examined cattle. Further studies are now essential to confirm and extend our findings regarding the taxonomic status and host associations of Babesia sp. Sika 1 and Babesia sp. Sika 2.