Investigation On Epidemic Status And Gene Polymorphism Of Echinococcus Granulosus In Some Areas Of Tibet,China

Tibet Autonomous region is located in the southwest border of China,with a cold climate,vast pastoral areas,rich animal resources,and a large number of terminal and intermediate hosts suitable for Echinococcus parasitism.The Qinghai-Tibet Plateau is one of the areas with serious Echinococcus epidemic in China,and its special geographical environment and religious culture are also factors that can not be ignored.In order to understand the prevalence and infection characteristics of echinococcosis in yaks and sheep in some areas of Tibet,and to analyze the risk factors affecting infection,to grasp the genotypes of echinococcosis prevalent in this area.In this study,the infection status and genetic diversity of echinococcosis were analyzed in Saga County,Zhongba County,Gangba County,Anren County,Bianba County and Mangkang County of Xigaze City,Tibet Autonomous region,and the infection status and genetic diversity of echinococcosis were analyzed by PCR amplification of mitochondrial cox1 and nad1 gene fragments of echinococcosis,and then the infection rate of echinococcosis and its influencing factors were investigated and analyzed.In order to provide data reference for the control of this zoonotic parasitic disease in Tibet,China.The specific research work is as follows:1.Investigation and analysis of cyst development of Echinococcus granulosusThe cysts in the infected organs were removed with scalpels,scissors and tweezers,and the quantity and quality of vesicles on the organs were calculated.The fluid in the capsule was absorbed with a syringe and packed in a centrifuge tube.Rinse the germinal layer in the corresponding cyst fluid and install it in a new centrifuge tube.A little cystic fluid was repeatedly sucked with a straw and placed on the glass slide.after the cover glass was covered,the protoscolex was observed under light microscope.A total of 301 echinococcosis cysts were obtained,of which the number of calcified cysts reached 113,accounting for about 37.54% of the total cysts(113/301),and 51 fertile cysts,accounting for about 16.94% of the total cysts(51/301).In 132 cattle and sheep samples in this study,echinococcosis was mostly parasitic in the liver and lungs of cattle and sheep,and no cysts were found in other organs.The phenomenon of parasitism only on the liver was the most serious,followed by mixed infection of liver and lung.Mixed infection of liver and lung is more common in yaks and liver infection is more common in sheep.2.Analysis of genetic Diversity of cox1 and nad1 Gene isolates of Echinococcus granulosus in cattle and SheepThe cox1 and nad1 gene fragments of 546 bp and 219 bp mitochondrial genomes were used to detect PCR and DNA sequence of infected yaks and sheep in some areas of Tibet,and the target gene fragments were amplified.Through the Blast function of NCBI website,it was verified again that the prevalent echinococcosis genotypes in this area were mainly narrow Echinococcus granulosus(G1,G3).Combined with the alignment results,the cox1 and nad1 gene sequences were aligned by MEGA7 software,and the haplotypes of cox1 and nad1 genes were analyzed by Dna SP5 software.The diversity of haplotypes was analyzed by population index and neutral index.Finally,it was found that the nucleotide diversity of cox1 gene was low and the haplotype diversity was high,while the nad1 gene sequences of Echinococcus in various regions of Tibet and even in China showed the characteristics of low haplotype diversity and low nucleotide diversity.3.Investigation on infection of Echinococcus granulosus and analysis of influencing factors in some areas of Tibet,ChinaThe infection of echinococcosis in some areas of Tibet was examined by sampling survey,and the risk factors affecting the infection were analyzed.This study shows that the infection rate of echinococcosis is high in some areas of Tibet.at present,the main risk factor of sheep echinococcosis in the survey area is age difference,and reasonable intervention should be carried out according to the relevant risk factors to reduce the risk of infection.To sum up,this study revealed the current situation of Echinococcus granulosus infection in six counties of Tibet,determined the genotype of Echinococcus granulosus in this area,and provided data support for local government departments and farmers to formulate effective prevention and control measures.