Histopathological, molecular, and phylogenetic analyses of Echinococcus species isolated from humans in Mongolia, 2010-2024.

Echinococcosis in humans caused by hydatid cyst of Echinococcus spp., remains a significant public health concern in Mongolia. In this study, we aimed to characterize the epidemiology, histopathological features, and molecular diversity of Echinococcus isolates from human infections. A retrospective analysis of surgically confirmed cases diagnosed between 2010 and 2024 was conducted. A histopathological examination of resected or biopsied cyst material was employed to assess cyst morphology and associated tissue responses. Molecular identification was performed using PCR amplification and sequencing of the mitochondrial cytochrome c oxidase subunit 1 (COX1) gene, followed by Bayesian phylogenetic analysis. A total of 311 human echinococcosis cases from multiple provinces were analyzed. Furthermore, COX1 sequences identified 181 isolates of Echinococcus granulosus sensu stricto (G1), 106 of E. canadensis (G6/7), 19 of E. canadensis (G10), and 5 of E. multilocularis, revealing 11 haplotypes. Geographic clustering of selected genotypes was observed. Bayesian phylogenetic reconstruction demonstrated clustering of Mongolian isolates within established Echinococcus lineages. Time-scaled analyses provided insights into the relative temporal relationships among lineages; however, divergence time estimates were interpreted cautiously owing to reliance on a substitution rate prior and single mitochondrial marker. These findings provide updated epidemiological and molecular data on human echinococcosis in Mongolia. However, given the single-locus design and exclusive use of human-derived samples, interpretations regarding transmission dynamics remain inferential and require confirmation through integrated host-based studies.