Human Spotted Fever Group Rickettsia Infecting Yaks (Bos grunniens) in the Qinghai-Tibetan Plateau Area

Abstract

The Qinghai-Tibetan Plateau Area (QTPA) is a plateau with the highest average altitude, located in Northwestern China. There is a risk for interspecies disease transmission, such as spotted fever rickettsioses. However, information on the molecular characteristics of the spotted fever group (SFG) Rickettsia spp. in the area is limited. This study performed screenings, and detected the DNA of human pathogen, SFG Rickettsia spp., with 11.3% (25/222) infection rates in yaks (Bos grunniens). BLASTn analysis revealed that the Rickettsia sequences obtained shared 94.3–100% identity with isolates of Rickettsia spp. from ticks in China. One Rickettsia sequence (MN536161) had 100% nucleotide identity to two R. raoultii isolates from Chinese Homo sapiens, and one isolate from Qinghai Dermacentor silvarum. Meanwhile, another Rickettsia sequence (MN536157) shared 99.1–99.5% identity to one isolate from Dermacentor spp. in China. Furthermore, the phylogenetic analysis of SFG Rickettsia spp. ompA gene revealed that these two sequences obtained from yaks in the present study grouped with the R. slovaca and R. raoultii clades with isolates identified from Dermacentor spp. and Homo sapiens. Our findings showed the first evidence of human pathogen DNA, SFG Rickettsia spp., from animals, in the QTPA.

Epidemiological Investigation of Tick-Borne Bacterial Pathogens in Domestic Animals from the Qinghai–Tibetan Plateau Area, China

“…Rickettsia spp., categorized under the spotted fever group (SFG), have been identified as causative agents of zoonotic diseases affecting humans, domestic animals, and wildlife, thus emerging as a significant global health concern [19]. In China, several species, including R. heilongjiangensis, R. sibirica subsp.…”

“…XY99, and Candidatus Rickettsia tarasevichiae, have been reported [20][21][22][23][24][25][26]. While Rickettsia is predominantly present in ticks within the Qinghai Plateau [19,[27][28][29], there is limited information regarding its incidence in domestic animals.…”

Spotted Fever Group Rickettsia Infecting Ticks (Acari: Ixodidae), Yak (Bos grunniens), and Tibetan Sheep (Ovis aries) in the Qinghai–Tibetan Plateau Area, China

“…In the Russian Far East, Kazakhstan, northern China, and Mongolia, R. sibirica and R. raoultii are widely distributed ( 4 ). In China, 11 SFG Rickettsia species have been detected in tick vectors and animals, some of which have been characterized as human pathogens ( 6 ). In previous reports, SFG Rickettsia was detected in a variety of ticks, including Haemaphysalis qinghaiensis in Yunnan Province and Harbin Province in China ( 5 , 7 , 8 ).…”

“…Yaks and Tibetan sheep are indigenous animals on the QTPA, which are the important sources of milk, meat, fur, skins, and dung in the area, contributing to the local economic development and the lives of herdsmen ( 10 ). Although SFG rickettsioses in livestock have been reported in this area, the information on these pathogens are limited ( 6 , 11 ). H. qinghaiensis is a common and endemic three-host tick on the QTPA, which is easy to parasitize on Tibetan sheep, yaks, sheep, goats, and other domestic animals to transmit a variety of diseases ( 9 ).…”

Severe Case of Rickettsiosis Identified by Metagenomic Sequencing, China

“…Two main groups of Rickettsia have been described on the basis of genetic differences and pathology, spotted fever group (SFG) and typhus group (TG). In China, 5 members of SFG have been identified in human cases ­­( 1 – 4 ), and 7 kinds of Rickettsia have been detected from ticks or animals in the Qinghai–Tibet Plateau, including R. heilongjiangensis, R. raoultii, R. slovaca, and R. sibirica , which are known to be pathogenic to humans ( 5 – 7 ). However, clinical cases have not been reported.…”