Areas Of Yunnan Research Articles

Numerical simulation study on ore-forming factors of the Gejiu ore deposit, China

The Gejiu superlarge tin polymetallic mining area in Yunnan hosts the largest tin-copper polymetallic ore field worldwide. The output of tin and copper provides power for the development of the country. Therefore, the study of mineralization is very important. But the geological structure is diverse, and the mineralization of different geological structures is different. In this study, the geological characteristics, tectonics, mineralogy, and geochemistry of these typical magmatic hydrothermal deposits were analyzed, various geological structures are studied, and the finite-element method was used to simulate the mineralization of chalcopyrite in the study area. Finally, the results are validated against the instance area. The numerical results show that the hydrothermal flow is the main factor controlling the mineralization. The pore fluid flow is driven by the temperature gradient. Favorable metallogenic areas are located in faults, between horizontal strata, and at intersections of faults. In the future, by simulating the metallogenic region and studying the metallogenic structure, the locations of ore bodies can be predicted. Our research confirms the results of the coupled model in the field of emerging computational geoscience and provides insights into the mineralization process.

Low-elevation endemic Rhododendrons in China are highly vulnerable to climate and land use change

The combination of climate change and land use change may have profound effects on terrestrial biodiversity in more significant ways than either has separately. However, most studies focus largely on the climate change impacts, which hampers our ability to develop appropriate conservation strategies in a dramatically changing world. Here, we predict the distributions of 191 Chinese endemic Rhododendron species under future climate and land use change, combining two dispersal constraint scenarios by using a species distribution model. We then assess the vulnerability and extinction risk of these species and identify areas at risk of highest species loss. We find that 52% of the species are predicted to expand and shift their geographic ranges, typically to the northwest and north. The remaining 48% of species are predicted to contract in geographic ranges under the 'perfect-dispersal' scenario. And only 7% of Rhododendron are predicted to keep 'still', while the rest of species shrank with varying degree under the 'no-dispersal' scenario. Species lost particularly at lower elevations, and we also identify four regions at particularly high risk from the impacts of climate and land use change, namely the parallel ridge-and-valley areas of eastern Sichuan, southeastern Tibet, western and eastern Yunnan, southern Shaanxi, plus scattered areas in Guangdong, Hainan and Taiwan. We conclude that Chinese endemic Rhododendron species at lower elevations are highly vulnerable to climate and land use change, facing an elevated risk of extinction under varying scenarios. These species therefore call for more attention and protection. We highlight the critical role of endemic Rhododendron species as good indicators for measuring, evaluating and understanding the effectiveness of our biodiversity conservation efforts. Our work provides insight into the status, trends and threats regarding endemic Rhododendron species, identifying risks and prioritizing conservation in a rapidly changing world.

Strain characteristics distribution and potential information analysis in Yunnan based on GNSS data

Based on the observation data of 211 Global Navigation Satellite System (GNSS) regional stations from 2011 to 2016, and 59 continuously operating GNSS stations in the Yunnan region of China since 2013, we analyzed the strain characteristics of Yunnan from the following two perspectives. On the one hand, we analyzed the strain characteristics and tried to determine the potentially abnormal areas of Yunnan based on a multi-scale spherical wavelet method, from an overall strain background view. On the other hand, we investigated the relationship between the strain time series and the potentially abnormal areas of Tonghai County through an earthquake case study, and we attempted to extract the potentially information before the earthquake from the strain time series based on Hilbert-Huang transform (HHT), from a local strain time-series view. The results showed that: (1) in the integrated solution processing of the regional strain patterns, the spherical wavelet method can adapt to the spatial variability in station density and estimate the strain patterns at multiple scales; and (2) by combining the long-term characteristics of the strain time series, the grid division, the two times standard deviation constraint, and the HHT dynamic analysis, it gives the some potential information details on the eve of an earthquake such as the Tonghai earthquake.

Genetic differentiation of geographic populations of Rattus tanezumi based on the mitochondrial Cytb gene.

Rattus tanezumi is a common domestic rat and host of the bubonic plague pathogen in China and Southeast Asia (SEA). The origin, genetic differentiation and dispersal of R. tanezumi have received increasing attention from researchers. The population genetics of R. tanezumi based on its mitochondrial cytochrome b gene have been studied to explain the origin, relationships and dispersal of populations. In this study, we captured a total of 229 rats; morphological and molecular biological identification cytochrome oxidase subunit I (COI) confirmed 131 R. tanezumi individuals collected from 6 provincial areas, and their Cytb gene sequences were analyzed. The results showed that the population in Mohan (MH), Yunnan, had the highest genetic diversity, while that in Ningde (ND), Fujian, had the lowest. Tajima’s D statistic for all populations was negative and nonsignificant, indicating the possible expansion of R. tanezumi populations. Low gene flow occurred between the Zhangmu (ZM) R. tanezumi population and other populations, and the genetic differentiation among them was high. Furthermore, our analyses revealed the ZM lineage was the oldest lineage among the groups and diverged ~1.06 Mya, followed by the Luoyang (LY) lineages (~0.51 Mya) and Yunnan lineage (~0.33 Mya). In southeastern Yunnan, the Jinshuihe (JSH) and MH populations were more closely related to the populations in southeastern China (Fuzhou (FZ), ND, Quanzhou (QZ), Nanchang (NC)) and inland areas (Chongqing (CQ), LY) than to those in other areas of Yunnan (Jiegao (JG) and Qingshuihe (QSH)), indicating that R. tanezumi may have spread from southeastern Yunnan to the interior of China. In summary, R. tanezumi may have originated in ZM and adjacent areas, spread to Yunnan, and then spread from the southeast of Yunnan inland or directly eastward from ZM to inland China.

The Study on Normalization Mechanism of Consolidating Poverty Alleviation Achievements in China’s YunnanGuangxi Border Areas

For a long time, poverty reduction has been the focus of academic circles—scholars at home and abroad explain and explore the development law and spatial evolution of poverty from economics, ethnology, geography and other disciplines, and study poverty reduction practice, experience, population, and economic development. However, there are few research results from the perspective of defining the cross-border ethnic groups in Yunnan, Guangxi and Southeast Asia and consolidating poverty alleviation results. Yunnan-Guangxi border areas overcome various unfavorable conditions including natural environment, develop steadily, and get rid of poverty by the end of 2020. Although great progress has been made in the areas of politics, economy, society and people’s livelihood in the border areas of Yunnan and Guangxi, there are still complex domestic and international factors affecting the consolidation of poverty alleviation achievements in this area. In the future, it is necessary to strengthen the dynamic monitoring and mechanism construction of poverty alleviation, enhance the economic “hematopoietic function” of border areas, strengthen domestic and foreign cooperation and create a good border environment, so as to consolidate the hard-won poverty alleviation achievements and realize rural revitalization.

Early Cambrian (Stage 4) brachiopods from the Shipai Formation in the Three Gorges area of South China

AbstractDiverse and abundant fossil taxa have been described in the lower Cambrian Shipai Formation in the Three Gorges area of Hubei Province, South China, but the taxonomy and diversity of the co-occurring brachiopod fauna are still far from clear. Here we describe the brachiopod fauna recovered from the Shipai Formation in the Three Gorges area of South China, including representatives of the subphylum Linguliformea: linguloids (Lingulellotreta ergalievi,Eoobolus malongensis, and Neobolidae gen. indet. sp. indet.), and an acrotretoid (Linnarssonia sapushanensis); and representatives from the subphylum Rhynchonelliformea: the calcareous-shelled Kutorginates (Kutorgina sinensis,Kutorginasp., andNisusia liantuoensis). This brachiopod assemblage and the first occurrence ofLinnarssonia sapushanensisshell beds permit correlation of the Shipai Formation in the Three Gorges area of Hubei Province with the Stage 4 Wulongqing Formation in the Wuding area of eastern Yunnan. This correlation is further strengthened by the first appearance datum (FAD) of the rhynchonelliform brachiopodNisusiain the upper silty mudstone of both the Shipai and Wulongqing formations. The new well-preserved material, derived from siliciclastic rocks, also gives critical new insights into the fine shell structure ofL.sapushanensis. Microstructural studies on micromorphic acrotretoids (likeLinnarssonia) have previously been restricted to fossils that were acid-etched from limestones. This is the first study to carry out detailed comparative ultrastructural studies on acrotretoid shells preserved in siliciclastic rocks. This work reveals a hollow tube and solid column microstructure in the acrotretoid shells from the Shipai Formation, which is likely to be equivalent of traditional column and central canal observed in shells dissolved from limestones.

Population occurrence of the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), in the winter season of China

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), has become an important pest in Chinese agricultural systems since its invasion on 11 December 2018. After its establishment, FAW months in the year-round breeding region have become the main source population migrating to other areas in China. Field investigations were conducted in tropical and subtropical regions to improve understanding of its year-round breeding area in China. The results showed that FAW larval density was significantly correlated with the seasonal temperature of the location surveyed. The FAW larvae maintained a high density in the tropical area and were frequently found in sites of the south subtropical region, but were absent from the north subtropical region and the northern part of the central subtropical region. These results indicated that FAW can reproduce annually in the tropical and south subtropical regions of China, including Hainan, Taiwan and the southern area of Fujian, Guangdong, Guangxi, Guizhou, and Yunnan. Hence, great effort should be made to monitor and control FAW in the year-round breeding region to suppress the population density of this area and to reduce migration of moths into northern parts of China. This study clarifies the occurrence area of the pest in winter in China and provides much valuable information for its population forecasting and management.

Eco-engineering controls vegetation trends in southwest China karst

The karst area in Yunnan-Guangxi-Guizhou region in southwest China is known for widespread rocky desertification but several studies report a greening trend since the year 2000. While the start of the greening trend seems to match with the implementation of ecological conservation projects, no statistical evidence on a relationship between vegetation greening and eco-engineering exists. Moreover, dominant factors influencing the spatial patterns of vegetation trends have rarely been investigated. Here we use six comprehensive factors representing the natural conditions and human activities of the study area, and several statistical models consistently show that eco-engineering explains large parts of the positive vegetation trends in the karst areas, while negative vegetation trends in non-karst areas of Yunnan were related with a decrease in rainfall. We further show that the interaction of eco-engineering with other factors leads to a heterogeneous pattern of different vegetation trends. Knowing and understanding these patterns is crucial when planning ecological restoration, especially in diverse landscapes like China karst and the methods can be reused in other restoration areas.

Geochemical characteristics and behaviour of elements during weathering and pedogenesis over karst area in Yunnan–Guizhou Plateau, southwestern China

A study of two typical red soil profiles, Gumu (GM-limestone) and Sanjiacun (SJC-dolomite) was conducted at Yunnan–Guizhou Plateau, China. The study employed mineralogy, geochemical and elemental ratios to assess the mobilisation and distribution of elements during weathering and pedogenesis. The mineralogy results revealed similarity in distribution of secondary minerals in both profiles, with exception at the ferricrete layer. The results revealed inheritance relationship between red soils and their underlying bedrocks indicating that clay minerals were likely derived from in situ weathering products or metasomatic process rather than detrital process. During weathering and pedogenesis process, alkaline elements such as K and Rb behave similarly and were closely related. All lanthanide elements except for Ce shared similar transport trend with Y and Be; however, Be exhibited significant enrichment at ferricrete layer of the dolomite profile. Transitional elements such as Co and Mn behave similarly; while, the High Field Strength Elements (HFSE) were stable, except for Th and Sc which indicate depletion in upper soil layer of the dolomite profile. Our findings further revealed that both profiles have experienced intense chemical weathering with high Chemical Index of Alteration values (CIA: 83–93) and a constant Ba/Sr ratio > 2. Overall, both profiles experienced similar elemental behaviour with the accumulation of major elements, the leaching of alkaline earth elements and the fluctuation of trace elements including Rare earth elements (REEs). The elemental behaviour was primarily controlled by redox reaction, pH, water availability, ionic radii and the stability of secondary oxides/hydroxides. Our study further highlights the use of newly proposed geochemical proxy Fe/Na ratio, which revealed high correlation (R2 ≈ 0.90) with U, Ba, Zn, Cu, Mo, Ni, Sb and REEs of power functions. These findings indicate that Fe/Na ratio may be used to investigate the behaviour of trace elements including REEs in highly weathered soils.

Spatial and temporal characteristics of carbon emissions from livestock farming in Yunnan province by state and city

The livestock industry is a pillar industry of the rural economy and an important industry of the national economy in Yunnan Province, so it is important to study the spatial and temporal characteristics of carbon emissions from the livestock industry in Yunnan Province for the development of a modern, lowcarbon and recycling livestock industry. This study draws on provincial greenhouse gas emission factors to calculate the carbon dioxide equivalents generated by enteric fermentation and manure management of cattle, sheep, pigs and poultry in each state and city of Yunnan Province. The results show that: (1) the total carbon emissions from the livestock sector in Yunnan Province decreased from 25, 643, 900 t in 2008 to 24, 758, 200 t in 2018, with an average annual carbon emission of 30, 534, 500 t and an average annual growth rate of The average annual growth rate was 0.35%, showing a characteristic of “rising first then falling”. (2) In terms of spatial and temporal evolution, the layout of the low and high livestock carbon emission areas in Yunnan is stable, while the medium and high livestock carbon emission areas fluctuate frequently and the spatial and temporal differences in carbon emissions are obvious. Finally, based on the conclusions, targeted countermeasure suggestions are put forward.

Registration of ‘YT 09‐13’ sugarcane

Abstract‘Yuetang 09‐13’ (‘YT 09‐13’) (Reg. no. CV‐197, PI 695070) sugarcane (a complex hybrid of Saccharum spp.) was selected and evaluated by the researchers of Institute of Bioengineering, Guangdong Academy of Sciences, from the progenies of a cross between YT 93‐159 (female) and ROC 22 (male). It was released to the growers in Guangdong Province, China, in July 2017. Yield data from three crop cycles (plant cane, first ratoon, and second ratoon) of 15 regional trials during 2015–2017 showed that the average cane yield of YT 09‐13 was 100.66 Mg ha−1, about 3.41% higher than that of ROC 22 (the check cultivar); the average sugar yield was 14.88 Mg ha−1, about 6.82% higher than that of ROC 22 (the check cultivar); and the average fiber content was 10.41%. YT 09‐13 is tolerant to drought and resistant to smut, Sugarcane mosaic virus, and brown rust diseases. YT 09‐13 is a suitable cultivar for planting and distributing in the main sugarcane areas of Hainan, Guangdong, Guangxi, and Yunnan.

Research for Biochemical Components of Sun-dried Green Tea in Different Tea Areas of Yunnan by Using PCA and Cluster Analysis Methods

This paper was to study the biochemical components and groups differences among 28 tea samples from different tea regions in yunnan. The biochemical components of 28 tea samples were analyzed by conventional method and high performance liquid chromatography. Principal component analysis and cluster analysis were used to classify 28 tea samples.The results showed that the mainly biochemical components of 28 tea samples,which included catechinepicatechin and epigallocatechin had large variation coefficients,56.88%,36.41% and 49.52%,respectively. The diversity index was 1.91,1.91 and 1.97,respectively. All above explained the characteristics of the samples in biochemical components were more abundant in the composition and performance of non-galloylatedcatechins. The samples were divided into 6 groups by cluster analysis,there were some differences in the content of biochemical components between the groups.

Research on the Development of E-commerce for Poverty Alleviation in Wumeng Mountain Area of Yunnan

Under the background of poverty alleviation, aiming at realizing the scientific, large-scale and intelligent development of Wumeng Mountain’s industry and the overall revitalization of the countryside, it is important to consider how to make good use of e-commerce tools in Wumeng Mountain, Yunnan, fully understand the importance of e-commerce poverty alleviation, combine the characteristics and advantages of regional industrial development, effectively resolve the constraints in the process of e-commerce poverty alleviation, optimize the combination of different e-commerce poverty alleviation models, innovate the development mechanism, and scientifically implement e-commerce poverty alleviation.

Reinventing Representations of “Local” Identity and Culture

This article explores social processes contributing to the reinvention of tourist destinations using ethnographic data collected at the case study site in Lashi Hai, a rural area in north-west Yunnan, China. Rather than reducing the reinvention process to marketing strategies or official development plans, the article shows that it may in fact reflect deeper social tendencies and is not only limited to the changing demands of visitors. Representing “local” identity, the reinvention of touristic places also becomes subject to negotiation among resident populations, contesting the values and symbolic statements applied to represent their “own” culture. It will be demonstrated that there are various important players involved in this process of reinvention, ranging from a strong central government, official development agencies and private investors to local cooperatives and finally individual residents – all with a stake in shaping and creating what is perceived as the “local” identity and culture.

Crustal structure in the Binchuan basin of Yunnan constrained from receiver functions on a 2-D seismic dense array*

The Binchuan region is located in a seismically active area in northwestern Yunnan, China. The detailed crustal structure is important to understand the tectonic evolution and to assess the seismic hazard in the study area. With a 2-D dense array deployed in this region, we use teleseismic receiver function traditional imaging methods, including the H-κ and common-conversion-point stacking methods, to derive high-resolution crustal thickness and νP/νS ratio maps. Our results indicate that the crustal thickness increases from ~40 km to ~46 km in the south-north direction, and the average crustal thickness beneath the Binchuan basin is ~42 km. Our results agree with previous results but have higher resolution due to dense interstation spacing.

Genetic Diversity of Phyllanthus emblica From Two Different Climate Type Areas.

Phyllanthus emblica L. is a well-known medicinal and edible plant species. Various medicinal compounds in the fruit make it an important medicinal and promising economic material. The plant is widely distributed in Southwestern and Southern China. However, due to massive deforestation and land reclamation as well as deterioration of its natural habitat in recent years, the wild resources of this species have been sharply reduced, and it is rare to see large-scale wild P. emblica forests so far. In order to effectively protect and rationally utilize this species, we investigated the genetic diversity, genetic structure, and population dynamics of 260 individuals from 10 populations of P. emblica sampled from the dry climate area in Yunnan and wet climate area in Guangxi using 20 polymorphic EST-SSR markers. We found high genetic diversity at the species level (He = 0.796) and within populations (He = 0.792), but low genetic differentiation among populations (FST = 0.084). In addition, most genetic variation existed within populations (92.44%) compared with variation among the populations (7.56%). Meanwhile, the NJ tree, STRUCTURE, and hierarchical analysis suggested that the sampled individuals were clustered into two distinct genetic groups. In contrast, the genetic diversity of the dry climate group (He = 0.786, Na = 11.790, I = 1.962) was higher than that of the wet climate group (He = 0.673, Na = 9.060, I = 1.555), which might be attributed to the combined effects of altitude, precipitation, and geographic distance. Interestingly, only altitude and precipitation had significant pure effects on the genetic diversity, and the former was slightly stronger. In addition, DIYABC analysis suggested the effective population size of P. emblica might have contracted in the beginning of the Last Glacial Maximum. These genetic features provided vital information for the conservation and sustainable development of genetic resources of P. emblica, and they also provided new insights and guidelines for ecological restoration and economic development in dry-hot valleys of Yunnan and karst areas in Guangxi.

Ethnic Disparities in Utilization of Maternal and Child Health Services in Rural Southwest China.

Background: Studies in China on ethnic disparities in access to health care in remote and rural population remain insufficient. This study aimed to assess the disparities in utilization of maternal and child health (MCH) services, including antenatal care (ANC), hospital birth, child growth monitoring, and immunization compliance between Han and ethnic minority women in Yunnan Province. Methods: A multi-stage sampling scheme was used to randomly recruit women from 40 townships in 14 remote prefectures of extremely remote areas in Yunnan. From birth records, we identified and recruited 303 Han women and 222 ethnic minority women who had given birth to a child within 3 years for an interview. Results: Overall, 96% of women used the ANC checkups and more than 95% had infants born in hospitals. However, the proportion of women compliant with early ANC visits (having antenatal care in the first trimester) was 22.5% lower in minority women than in Han women (61.3% vs. 83.8%, p < 0.001) with an adjusted odds ratio (aOR) of 2.04 (95% confidence interval (CI) of 1.13–3.66) for the minority group. The proportion of children under one year old with immunizations completed in a timely manner was also lower in minority families than in Han families (80.2% vs. 86.8%, p < 0.05) with an aOR of 1.99 (95% CI = 1.16–3.40). Conclusions: Ethnic disparities remain in utilization of early ANC visits and timely immunization completion for newborns. Ethnic minority women tended to lag behind for both. Further intervention should focus on assisting minority women living in extremely rural areas to comply with the MCH policy. Culturally-sensitive policies and skills are needed, and priority should be given to improve utilization of early ANC and timely immunization completion.

Analysis of 1 364 cases of acute poisoning in tropical areas of Yunnan

Objective To investigate the occurrence and characteristics of acute poisoning events in the tropical regions of Yunnan Province, we provide evidence for prevention and control measures. Methods A three-level general hospital in typical tropical area of Yunnan Province was selected as the research object. All the cases of acute poisoning during 2013.01.01 to 2018.12.31 were retrieved from the information system to analyze the characteristics of population, the type of poisoning, the season of poisoning event and treatment effect. Results A total of 1 364 cases of acute poisoning were collected during the 6 years. Acute poisoning occurred in all age groups, and 20 to 50 age groups accounted for 60.19% of all cases. On poisoning substances, agricultural chemicals, drugs, herbal medicines and plant poisoning accounted for 48.39%, 16.72% and 11.80% respectively. Among them, paraquat, organophosphorus pesticide, wild mushroom, aconitine and rodenticide were 244, 189, 96, 90, 89 cases respectively, which took the top 5. A wide range of tropical poisonous plants that caused acute poisoning. Almost all the wild mushroom poisoning cases and 57.26% of all the poisoning cases occurred in the rainy season. Also, much more cases of agricultural chemicals poisoning occurred in rainy season than the dry season. In terms of therapeutic effect, the treatment effect of paraquat was proven to be poor, for the death and unhealed cases got to 44.90% when discharge. The mortality rate of organophosphorus pesticides was also as high as 8.47%. Conclusion The incidence of acute poisoning in tropical areas of Yunnan Province is still high, especially caused by agricultural chemicals, wild mushroom, herbal medicines and poisonous plants. It is necessary to strengthen publicity and improve the emergency response system, in order to effectively reduce the occurrence and harm of acute poisoning accidents. 摘要：目的 探讨云南省热带地区急性中毒事件的发生规律和特点,为制定预防和控制措施提供依据。 方法 以 云南省的热带地区某三级综合医院为对象, 从该医院信息系统中调取 2013 年 1 月 1 日—2018 年 12 月 31 日出院的急性 中毒病例数据, 对中毒人群、中毒类型、中毒发生的季节及治疗效果等进行分析。 结果 该院 6 年期间共收治急性中毒 1 364 例, 各年龄段均有发生, 其中 20~<50 岁占总病例的 60.19%。导致中毒的物质中, 农药、化学药物、草药及植物性中 毒分别占总量的 48.39%、16.72% 和 11.80%, 其中百草枯、有机磷农药、野生菌、乌头碱、杀鼠剂分别为 244 例、189 例、96 例、90 例、89 例, 居前 5 位。导致中毒的热带毒性植物品类繁多。中毒病例发生在雨季的占总量的 57.26%, 其中野生菌 中毒几乎全部发生在雨季, 农药中毒雨季也显著高于旱季。治疗效果上, 百草枯治疗效果差, 出院时死亡和未愈病例 占 44.90%, 有机磷农药死亡率也高达 8.47%。 结论 云南省热带地区急性中毒发生率高, 其中农药类、野生菌、有毒植 物中毒问题突出。应加强宣传, 提高对急性中毒的关注, 完善应急处理体系,以期有效地降低急性中毒事件的发生及 危害。

Potential risks of Tithonia diversifolia in Yunnan Province under climate change

AbstractYunnan province is known for its extraordinarily rich biodiversity, but this is threatened by invasive species under climate change. In the present study, the current and future potential distribution of an invasive grass—Tithonia diversifolia A. Gray in Yunnan province were predicted by species distribution modeling, under two climate change conditions (RCP2.6 and RCP8.5) through to 2050s. In addition, the potential risk of T. diversifolia to the protected areas of Yunnan was examined. Our results showed that the potential distribution areas of T. diversifolia would increase by 12 and 93% by 2050s, under RCP2.6 and RCP8.5, respectively. Yunnan's protected areas are now susceptible to T. diversifolia, and the scope of this plant's effects would continue to expand under climate change. A total of 26 protected areas are currently impacted by T. diversifolia, in a total affected range area of 2,822 km2, but by 2050s, this is predicted to increase by 23 and 53%, and would lead to one and 13 protected areas newly threatened under RCP2.6 and RCP8.5, respectively. These results suggest that T. diversifolia would benefit from global warming, we should prevent further global warming. In addition, human disturbance should be reduced and prohibited to protect native plants and forest ecosystem in southern, southeastern and northwestern part of Yunnan.

A large-scale fatal outbreak of Pasteurella multocida among wild rodents in southwestern China

BackgroundPasteurella multocida is an important and old zoonotic pathogen worldwide which has an impressive host spectrum including numerous domestic and wild animals as well as birds, causing specific diseases or outbreak with great economic impact. It has never been reported that P. multocida can cause an epidemic in wild rodents. In June 5–17, 2016, more than 1000 rodent deaths of an unknown cause quickly spread in the PuEr City, Yunnan province, southwestern China. MethodsThe rodents in affected areas and outside of the epidemic areas were collected and screened for possible known pathogens including Yersinia pestis, rabies virus and hantavirus as well as other bacteria. The possible bacterial pathogens were isolated both by culture medium and by mouse inoculation in parallel. The isolates were identified by the Vitek GNI card and PCR assays for 16S rRNA genes. The pathogen strains were selected for whole genome sequencing analysis. ResultsA total of 123 rodents were collected from 25 sample sites at affected area, among of which, all 119 dead rodents were negative for the pathogen under consideration except P. multocida, and all four live rodents were negative for P. multocida. In addition, 480 rodents collected from other 23 counties outside of the epidemic area in Yunnan were negative for with P. multocida. A total of 14 strains of P. multocida (six directly isolated from the field rodents and eight from the experimental mice that were injected with the organ substrates from the dead rodents) belonged to serogroup A and serogroup F represented by 9 N and 20 N were identified in these epidemic areas. Whole genome sequencing revealed that the serogroup F strain shared 99% similarity to P. multocida Pm70 from chicken, but contained a 50 k bp insertion sequence. The serogroup A strain shared 95% similarity to P. multocida FDAARGOS_385 from a human patient, but contained four large structural differences. Histological abnormalities were identified in the livers, lungs, hearts and brains of the inoculated mice. ConclusionsThe simultaneous occurrence of both serotypes of P. multocida may have caused this sudden onset of mortality across the local rodent population in Yunnan Province, China. Further attention should be paid to this old bacterium in the world.