[Source: PLoS Neglected Tropical Diseases, full page: (LINK). Abstract, edited.]
OPEN ACCESS / PEER-REVIEWED / RESEARCH ARTICLE
Human plague associated with Tibetan sheep originates in marmots
Ruixia Dai , Baiqing Wei , Haoming Xiong, Xiaoyan Yang, Yao Peng, Jian He, Juan Jin, Yumeng Wang, Xi Zha, Zhikai Zhang, Ying Liang, Qingwen Zhang, Jianguo Xu, Zuyun Wang, Wei Li
Published: August 16, 2018 / DOI: https://doi.org/10.1371/journal.pntd.0006635
The Qinghai-Tibet plateau is a natural plague focus and is the largest such focus in China. In this area, while Marmota himalayana is the primary host, a total of 18 human plague outbreaks associated with Tibetan sheep (78 cases with 47 deaths) have been reported on the Qinghai-Tibet plateau since 1956. All of the index infectious cases had an exposure history of slaughtering or skinning diseased or dead Tibetan sheep. In this study, we sequenced and compared 38 strains of Yersinia pestis isolated from different hosts, including humans, Tibetan sheep, and M. himalayana. Phylogenetic relationships were reconstructed based on genome-wide single-nucleotide polymorphisms identified from our isolates and reference strains. The phylogenetic relationships illustrated in our study, together with the finding that the Tibetan sheep plague clearly lagged behind the M. himalayana plague, and a previous study that identified the Tibetan sheep as a plague reservoir with high susceptibility and moderate sensitivity, indicated that the human plague was transmitted from Tibetan sheep, while the Tibetan sheep plague originated from marmots. Tibetan sheep may encounter this infection by contact with dead rodents or through being bitten by fleas originating from M. himalayanaduring local epizootics.
Plague is mainly a disease of wild rodents, and their parasitic fleas are considered the transmitting vectors. However, human plague originating from Ovis aries (Tibetan sheep) is found in the Qinghai-Tibet plateau in China, where Marmota. himalayana is the primary plague host. Tibetan sheep-related human plague infection is always associated with slaughtering or skinning diseased or dead Tibetan sheep. The plague in Tibetan sheep clearly lags that in M. himalayana. In this study, we performed a genome-wide single nucleotide polymorphism analysis of Tibetan sheep-related plague events, including pathogens isolated from humans, Tibetan sheep, and marmots. Through genomic analysis, together with the epidemiological connections, we confirmed that human plague came from Tibetan sheep, and the Tibetan sheep plague originated from marmots. Tibetan sheep account for about 1/3 of the total number of sheep in China. Tibetan sheep and goats are important domestic livestock on the Qinghai-Tibet plateau. Therefore, the hazards of Tibetan sheep plague should not be underestimated.
Citation: Dai R, Wei B, Xiong H, Yang X, Peng Y, He J, et al. (2018) Human plague associated with Tibetan sheep originates in marmots. PLoS Negl Trop Dis 12(8): e0006635. https://doi.org/10.1371/journal.pntd.0006635
Editor: Didier Raoult, Faculté de Médecine,Aix-Marseille Université, FRANCE
Received: April 21, 2018; Accepted: June 25, 2018; Published: August 16, 2018
Copyright: © 2018 Dai et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: All relevant data are within the paper and its Supporting Information files.
Funding: This work was supported by grants from the National Natural Science Foundation of China (81260438 and 81290340), a Provincial Applied Basic Research Project of Qinghai (2016-ZJ-789), and a National Priority Development Project on Key Science Instruments (2012YQ09019706). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Keywords: Yersinia Pestis; Plague; Human; Sheep; Wildlife; China; Tibet.