Echinococcus spp. and genotypes infecting humans in Tibet Autonomous Region of China: a molecular investigation with near-complete/complete mitochondrial sequences

Abstract

Background Molecular markers are essential to identify Echinococcus species and genotypes in areas with multiple Echinococcus species to understand their epidemiology and pathology. Tibet Autonomous Region (TAR) is one of the areas worst hit by echinococcosis. However, molecular epidemiology is still missing among echinococcosis patients in TAR. This research explored the Echinococcus species and genotypes infecting humans in TAR and the population diversity and the possible origin of G1 in TAR. Methods Cyst samples were collected in one echinococcosis-designated hospital in TAR. Echinococcus species and genotypes were identified through a maximum-likelihood approach with near-complete/complete mtDNA using IQ-TREE. Phylogenetic networks were built with PopART, and the phylogeographical diffusion pattern was identified using a Bayesian discrete phylogeographic method. Results Using phylogenetic trees made with near-complete/complete mtDNA obtained from 92 cysts from TAR patients, the Echinococcus species and genotypes infecting humans in TAR were identified as Echinococcus granulosus (s.s.) G1 (81, 88.04%), accounting for the majority, followed by G6 of the E. canadensis cluster (6, 6.52%), E. granulosus (s.s.) G3 (3, 3.26%), and E. multilocularis (2, 2.17%). An expansion trend and a possible recent bottleneck event were confirmed among the G1 samples in TAR. Adding the other near-complete mtDNA of G1 samples globally from the literature, we identified the possible phylogeographic origin of the G1 samples in TAR as Turkey. Conclusions Using near-complete/complete mtDNA sequences of Echinococcus spp. obtained from echinococcosis patients, a variety of Echinococcus species and genotypes infecting humans throughout TAR were identified. As far as we know, this is the first comprehensive molecular investigation of Echinococcus species and genotypes infecting humans throughout TAR. We identified, for the first time to our knowledge, the possible origin of the G1 in TAR. We also enriched the long mtDNA database of Echinococcus spp. and added two complete E. multilocularis mtDNA sequences from human patients. These findings will improve our knowledge of echinococcosis, help to refine the targeted echinococcosis control measures, and serve as a valuable baseline for monitoring the Echinococcus species and genotypes mutations and trends of the Echinococcus spp. population in TAR. Graphical Abstract

Mitogenomic exploration supports the historical hypothesis of anthropogenic diffusion of a zoonotic parasite Echinococcus multilocularis

“…A previous attempt using this approach succeeded in identifying the global diffusion routes and origin of the closely related parasite E chinococcus granulosus . 19 , 54 The present study supported 19 diffusion routes of E. multilocularis , including those into Hokkaido, some of which align with previous findings, such as invasions of European strains into North America. 55 , 56 However, the results should be interpreted cautiously because there is a lack or shortage of datasets from regions where E. multilocularis is prevalent, such as Russia and several European countries, including Germany and Switzerland.…”

Plasma Circulating Cell-Free DNA Facilitated the Detection of an Alveolar Echinococcosis Patient Initially Misdiagnosed as Cystic Echinococcosis: A Case Report

“…On the contrary, AE is more restricted in certain geographical regions, especially in the Northern Hemisphere [ 2 ]. A molecular investigation of near-complete/complete mitochondrial sequences of 92 patients’ samples from Tibet Autonomous Region (TAR) identified that the main Echinococcus species and genotypes infecting humans in TAR were Echinococcus granulosus sensu stricto G1 followed by G6 of Echinococcus canadensis (6.52%), and Echinococcus multilocularis (2.17%) [ 30 ]. However, in Shiqu County on the Tibetan Plateau of Sichuan Province, AE is more prevalent with a prevalence of 3.58%, which is significantly higher than the prevalence of CE at 2.31%, as reported in an ultrasound-based prevalence study screening on 84,742 residents [ 18 ].…”

Advances in Detecting Cystic Echinococcosis in Intermediate Hosts and New Diagnostic Tools: A Literature Review

“…Parasitology and epidemiology require mitochondrial gene genotyping of E. granulosus s.l. [ 72 ]. Studies of parasite diversity and population structure using mitochondrial genes are ideal.…”

“…Due to their diversity, specific mitochondrial genes, including COX1 and ND1 , are targeted for genetic studies [ 74 ]. PCR is used to amplify mitochondrial genes and increase the quantity of genetic material in mitochondria [ 72 ]. Genetic sequences of mitochondria are determined using DNA sequencing technologies like Sanger and Next-Generation Sequencing (NGS) [ 75 ].…”