Investigation on the infection of spotted fever group Rickettsiae and Rickettsia mooseri of wild rodents in the field of plague foci in Western Yunnan / 中华地方病学杂志

Objective:To investigate the infection of spotted fever group Rickettsiae (SFGR) and Rickettsia mooseri ( R.mooseri) of wild rodents in the field of plague foci in Western Yunnan. Methods:The DNA of liver samples of 2 512 wild rodents captured from the plague foci in Lianghe County, Jianchuan County and Yulong County in Western Yunnan from 2015 to 2016 was extracted by magnetic bead method, and the heat shock protein groEL gene primers were used for nested PCR amplification. Gene sequence splicing and Blast homology comparison were performed using DNAStar 7.1 software and GenBank of the National Center for Biotechnology Information (NCBI) of the United States, respectively, and DNAStar 7.1 and MEGA 6.0 softwares were used to construct phylogenetic trees.Results:The wild rodents infected with SFGR were Mus pahari, Rattus steini, Crocidura attenuata and Suncus murinus (one for each), with a total infection rate of 0.16% (4/2 512); no R.mooseri infection was detected. The SFGR infection rates of wild rodents in the plague foci of Lianghe County and Jianchuan County were 0.49% (3/611) and 0.10% (1/1 029), respectively; no SFGR infection was detected in the wild rodents in the plague foci of Yulong County. The homology analysis showed that the homology between SFGR positive samples and reference sequences was 95.45%-100.00%; some of the groEL gene sequences were highly similar among the four positive samples, and the homology was 89.60%-97.40%. Sequence evolution analysis showed that the sequences of three SFGR positive samples from the plague focus in Lianghe County were clustered in the same branch, and the homology reached 94.40%-97.40%; one positive sample sequence from the plague focus in Jianchuan County was clustered in one branch. Conclusion:SFGR infection rate of wild rodents in the field of plague foci in Western Yunnan is low, and no R.mooseri infection is found.

Hepatitis E virus infection and gene polymorphism in murine-shaped animals of plague foci in Yunnan Province / 中华地方病学杂志

Objective:To learn about the infection and gene polymorphisms of hepatitis E virus (HEV) in murine-shaped animals of plague foci in Yunnan Province.Methods:From July to August 2019, around 16 natural villages (4 in Mile City, 6 in Mangshi and 6 in Lianghe County), which were the foci of domestic plague in Yunnan Province, the murine-shaped animals were captured by the night-time method. The liver RNA was extracted, and the target gene of rat HEV was detected by one-step real-time fluorescence quantitative PCR, and the positive rate of rat HEV was calculated. The rat HEV positive samples were amplified by PCR for further clone sequencing, and the resulting sequences were compared with the HEV sequences registered in the GenBank and a phylogenetic tree was constructed by using MegAlign and MEGA 7.0.Results:A total of 491 murine-shaped animals were captured from 3 orders, 5 families, 8 genera, 15 species, and the positive rate of rat HEV was 4.89% (24/491). Among them, the positive rate of Rattus tanezumi and Niviventer fulvescens was 9.39% (23/245) and 1/3, respectively; and other species were negative. There was a statistically significant difference in the positive rate of rat HEV between different habitats ( P = 0.014), and the positive rate of rat HEV in the habitats near the dwellings was higher than that in other habitats ( P < 0.05). The sequence comparison analysis showed that the gene sequence of P018 from Lianghe County was 100.0% homologous to the MG813927.1 sequence of the first patient with rat HEV in Hongkong, and it was clustered into the same branch with the sequences of MG813927.1 and LC549185.1 from rat, was the type HEV C. G024 from Mangshi shared a low homology (20.7% - 31.5%) with other virus strains, and it was clustered into the same branch with a HEV sequence from an avian (AY535004.1). Conclusions:Rat HEV is prevalent in murine-shaped animals of plague foci of Yunnan Province, and there may be gene polymorphisms of rat HEV. In addition, the difference infection rate may be related to the habitats.

Analysis of metal elements in water samples of plague foci in Yunnan Province / 中华地方病学杂志

Objective:To detect and analyze the contents of eight metal elements in water samples of plague foci in Yunnan Province.Methods:During the period from December 2015 to November 2016, the plague foci of Yulong, Jianchuan and Lianghe were selected as sampling sites, water samples were collected in areas with rodent activities in the 4 seasons of spring, summer, autumn and winter. The contents of eight metal elements calcium (Ca), iron (Fe), zinc (Zn), chromium (Cr), plumbum (Pb), manganese (Mn), cadmium (Cd) and cuprum (Cu) in water samples were measured by flame atomic absorption spectrometry (FAAS), and the data [median (interquartile distance)] were statistically analyzed.Results:Twenty-six, 58 and 54 water samples were collected from Yulong, Jianchuan and Lianghe plague foci, respectively. The contents of metal elements of Pb and Cd in water samples of the three plague foci [Yulong: 0.19 (0.78) and 0.08 (0.07) mg/L; Jianchuan: 0.23 (0.56) and 0.03 (0.06) mg/L; Lianghe: 0.13 (0.61) and 0.09 (0.08) mg/L] were higher than that of "Environmental Quality Standards for Surface Water" (Pb: 0.10 mg/L, Cd: 0.01 mg/L). There were significant differences in the contents of Ca and Cd elements among the three regions ( P < 0.05), but there was no significant difference in the contents of the other 6 metal elements among the three regions ( P > 0.05). The content of Ca element was the highest in Yulong plague foci, and the lowest in Lianghe plague foci ( P < 0.017). In the Yulong plague foci, there was no statistically significant difference in the content of Fe element in different seasons ( P > 0.05), and the differences in the contents of the other 7 metal elements were statistically significant ( P < 0.05). There was no significant difference in the content of Cr element in Jianchuan plague foci in different seasons ( P > 0.05), and the differences in the content of the other 7 metal elements were statistically significant ( P < 0.05). There was no significant difference in the content of Ca element in Lianghe plague foci in different seasons ( P > 0.05), and the differences in the content of the other 7 metal elements were statistically significant ( P < 0.05). Conclusion:The metal element contents of Pb and Cd are relatively abundant in water samples from 3 plague foci of Yunnan Province, and the seasonal variation trend of metal element content in water samples of Yulong and Jianchuan plague foci is similar.

Investigation and analysis of geographic landscape characteristics in Yulong plague natural focus, Yunnan Province / 中华地方病学杂志

Objective To investigate the geographic landscape features in Yulong plague natural focus.Methods Four altitudinal gradients (2 400-,2 600-,2 800-,≥3 000 m) were selected as study objects in Yulong plague natural focus from December 2015 to November 2016 to collect and analyze geographic landscape factors (topography and terrain,climate,water areas,vegetation and soil) based on the literatures about this plague focus.Results Yulong plague natural focus was an area with mid-mountain and subalpine topography in northwestern Yunnan Province,and its terrain had the character of lower in the southeast and higher in the northwest.This area belonged to plateau warm temperate monsoon climate of low latitude with an average month temperature 13.6 ℃ from 2005-2016,month air relative humidity averaged 59.4％,and rainfall averaged 884.5 mm a year,which concentrated mostly from June to September.About 98.1％ of the water area in Yulong County was controlled by Chin-sha River.The vegetation and soil were characterized by vertical distribution along with altitude gradients obviously.Conclusion The unique geographical landscape of the plague natural focus in Yulong County is one of important factors affecting the occurrence and epidemic of the plague.

Community structure of wild myomorpha in the plague foci of Lianghe County, Yunnan Province / 中华地方病学杂志

Objective To investigate the community structure and spatial distribution of wild myomorpha in the plague foci of Lianghe County,Yunnan Province.Methods From December 2015 to October 2016,in Mangdong,Hexi,Nangsong and other places in Lianghe County,forest landscape samples were randomly selected in different altitude gradients (1 000 ～,1 200 ～,1 400 ～,≥ 1 600 m).Peanut was used as a bait for trapping myomorpha,and the community structure of myomorpha was analyzed.Results A total of 663 myomorpha were collected and the density was 7.97％ (663/8 320),which were divided into 16 species,11 genus,5 families,and 3 orders.Rattus tanezumi (30.62％,203/663) was the dominant species.In the 1 000-＜ 1 200 m altitude gradient,the richness of myomorpha was the highest (13 kinds).In the 1 400-＜ 1 600 m altitude gradient,the index of diversity (2.094 2) was the highest.With the increase of altitude,the ecological dominance were increased,and the values were 0.672 2,0.774 2,0.842 8,and 0.882 4,respectively,whereas the evenness presented a decreasing trend,and the values were 0.269 2,0.197 1,0.142 8,and 0.162 0.Conclusions The Rattus tanezumi has presented a single dominant distribution at different elevation and the number and the species of the wild rodent with superior position have increased with the altitude increased in Lianghe focus.With the increase of altitude,the diversity and the evenness have increased,whereas the richness and the dominance have decreased.

Analysis of eight metal elements contents in rat hole soil in Yunnan plague natural foci / 中华地方病学杂志

Objective To compare and analyze the soil eight metal elements contents of rat holes of three plague foci in Yunnan Province.Methods The soils were collected from the rat holes in Yulong,Jianchuan,and Lianghe plague foci.Calcium (Ca),iron (Fe),zinc (Zn),chromium (Cr),lead (Pb),manganese (Mn),cadmium (Cd),and copper (Cu) were quantified with flame atomic absorption spectrometry (FAAS).Data input,calculation and collation were conducted through Excel 2007,and statistical software SPSS 20.0 was used to carried out statistical analysis through rank sum test.Results The medians of Ca content in the rat hole soil of Yulong County,Jianchuan County,and Lianghe County,respectively,were 85.40,308.56,and 0.00 mg/kg;the medians of Fe were 2 569.07,1 950.16,and 975.72 mg/kg;the medians of Zn were 5.64,4.02,and 2.04 mg/kg;the medians of Cr were 1.09,3.06,and 0.71 mg/kg;the medians of Pb were 3.61,29.56,and 22.80 mg/kg;the medians of Mn were 223.01,212.97,and 80.43 mg/kg;the medians of Cd were 0.00,2.02,and 2.94 mg/kg;and the medians of Cu were 1.92,1.08,and 0.51 mg/kg.The contents of eight metal elements were statistically different in the soil samples between Yulong,Jianchuan,and Lianghe plague foci (H =80.538,127.687,202.583,185.359,124.747,150.057,91.346,228.546,P ＜ 0.05).Conclusions The content of Fe in soil of the three plague foci in Yunnan Province is abundant.The contents of metal elements of Yulong County and Jianchuan County are similar.

Relationship between geographic landscapes characteristics and plague / 中国人兽共患病学报

Plague,a highly virulent zoonotic disease,is caused by Yersinia pestis.Eco-geographic landscape plays an important role in the formation and evolution of plague natural foci.We explored the relationship between geographic landscape and plague as well as related techniques,which will be helpful for clarifying the suitable habitats,identifying the vulnerability of geographic environment,and preventing and controlling the occurrence of plague effectively.

Factors related to household rodent abundance in rodent-borne disease foci in western Yunnan / 中华流行病学杂志

Objective To analyze the factors related to the household abundance of rodents in rodent-borne disease foci in the western part of Yunnan province.Methods From July 2011 to October 2012,800 households (20 households in 1 village) were randomly selected in 40 natural villages of 10 counties in western Yunnan where rodent borne disease was endemic to conduct a study on relationship between rodent abundance and environmental factors.Five cages were placed in each household for 3 consecutive nights to capture rodents.The rodent species were identified based on their morphological characteristics.The data on potential factors related to rodent abundance were collected through questionnaires and field observation.A dataset was established by using EpiData software and the analysis was performed with hurdle regression model under R software.Results A total of 421 rodents were captured in 800 households,belonging to 9 species,6 genera,2 families,2 orders.Rattus tanezumi was the predominant species (66.03％).The final hurdle regression model showed that the probability of capturing rodents in the households where family member had high education level and the garbage was placed outside declined by 50％-68％ ; The probability of capturing rodents in the households of Dai and Yi ethnic groups increased by 2.16-2.87 times; The probability of capturing rodents in the households where rodents were observed or vegetables grown near houses increased by 1.54-1.59 times; In the households where many rodents were believed to exist,the probability of capturing rodents and the number of rodents captured increased by 1.59 and 1.84 times respectively.The number of rodents captured in the houses with cement or tile floor increased by 3.62 times.Conclusion The household abundance of rodents in the area in western Yunnan,where the rodent-borne disease survey was conducted,seemed to be closely related to the social economy status,human intervention and ecological environment.To control the abundance of rodents effectively,it is necessary to take these factors into consideration.