Objective Throush identify biochemical characteristics and virulence factors of 2 strains suspected Yersinia pestis(Y.pestis)isolated from the dead Marmota himalayana(M.himalayana)to confirm the nature epidemic focus in Dege County,Sichuan Province.Methods Y.pestis was analyzed by specific staining and shape,culturing characteristics,splitting-test by bacteriophage,test of biochemical characteristics and glycolysis ability,virulence factors,virulence,nutritional requirement,plasmid,genetic test and genetic type. Results The tested strains were Gram staining bacilus.The main biochemical characteristics were Arabinose(+)、 Rhamnose(-),Maltose(+),Melibiose(-),Glycerol(+),Denitrification(+).The virulence factors with FI+.VW+, Pgm+,Pst I+;and with the common 6.0×106,45.0×106,65.0×106 plasmids,also with the virulence-relative plasmid gene.Both their absolutely lethal dose(LD100)in mice were 50 bacteria.The nutritional requirement appeared which were depended on Phenylalanine and Methionine.With the Genomovar 5 genotype characteristics of M.himalayana plague foci of Qinghai-Tibet plateau.The difference between tested strains and Yersinia pseudotubercuosis on the 3 different culture medium was obvious.The tested strains had a Y.pestis' specific 3a fragment,Pst I and FI-Ag,at 22 ℃,the strains could be split by bacteriophage completely.Conclusions According to the diagnostic criteria of plague in China,the 2 suspected strains isolated from Dege County,Sichuan Province ale confirmed as Y.pestis.both with powerful virulenceand with the characteristics of the Y.pestis of M.himahtyana in Qinghai-Tibet plateau plague natural focus.

Objective To investigate the epidemiology of echinococcosis in Serthar County, Sichuan Province, so as to provide insights into optimization of echinococcosis control measures. Methods The prevalence of human echinococcosis was surveyed among permanent residents living in Serthar County at ages of over 2 years from 2016 to 2019, and the prevalence of Echinococcus infections was surveyed in owned dogs, yaks and rodents in 2019. The epidemiological features of echinococcosis in humans and animals were descriptively analyzed. Results The overall prevalence of human echinococcosis was 3.72% (1 613/43 362) in Serthar County from 2016 to 2019, and the prevalence rates of cystic echinococcosis, alveolar echinococcosis and mixed infections of cystic echinococcosis and alveolar echinococcosis were 1.72% (745/43 362), 1.98% (860/43 362) and 0.02% (8/43 362), respectively. The prevalence of human echinococcosis was higher in pastoral areas (4.13%, 1 577/38 149) than in semi-agricultural and semi-pastoral areas (0.69%, 36/5 213) (χ² = 151.82, P < 0.05); however, there was no significant difference in the prevalence between men (3.76%, 819/21 787) and women (3.68%, 794/21 575) (χ² = 0.19, P > 0.05). Cystic echinococcosis was the predominant type in students with echinococcosis (93.78%, 422/450), while alveolar echinococcosis was the predominant type in herders with echinococcosis (72.16%, 801/1 110). There was a significant difference in the constituent ratio of echinococcosis types between students and herders (χ² = 588.57, P < 0.05). In addition, higher prevalence of echinococcosis was detected in nomadic populations (4.58%, 1 008/22 021) than in community-dwelling populations (2.83%, 605/21 341) (χ² = 91.88, P < 0.05). The Echinococcus copro-antigen-positive rate was 0.19% (4/2 157) in owned dogs, and the detection rate of echinococcosis was 8.00% (16/200) in yaks and 3.10% (31/1 000) in rodents in 2019. Conclusions Echinococcosis is highly prevalent in Serthar County, Sichuan Province. Sustained management of source of Echinococcus infections, improved treatment of echinococcosis patients and timely health education for nomadic populations are recommended.