Epidemiology and genetic diversity of Echinococcus granulosus sensu stricto in the East Tianshan Mountains, Xinjiang, China.

Abstract

In Xinjiang, previous reports of cystic echinococcosis (CE) in livestock have focused on West and Middle Tianshan Mountains. In contrast, there is an absence of research on CE in the East Tianshan Mountains. To determine the epidemiology and genetic diversity of Echinococcus granulosus sensu stricto (s.s.) in domestic animals in the East Tianshan Mountains, Xinjiang, China, the livers and lungs of 1773 domestic animals were examined, between January 2023 and March 2023, and 40 cysts were collected. Polymerase chain reaction was used for the molecular diagnosis of the cysts. Statistical results showed that the overall prevalence of echinococcosis in sheep was 6.92% (114/1646), which was significantly higher than that in cattle (1.57%, 2/127). A total of 40 cyst isolates were obtained, including 38 from sheep and 2 from cattle. Genomic DNA was extracted, and the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene was amplified by PCR to obtain the target 850 bp fragment. The results revealed that all the isolates had the G1 genotype, with similarities ranging from 98.88-100%. Haplotype network analysis revealed 32 haplotypes of the cox1 gene, among which Hap_7 was the main haplotype. Furthermore, haplotype diversity (Hd = 0.313 ± 0.093) and nucleotide diversity (π = 0.00173 ± 0.00079) were lower in the East Tianshan Mountains than in other regions, indicating that the populations are genetically less differentiated. Tajima's D and Fu's Fs tests were negative (p ≤ 0.01), indicating an expansion of the population in the East Tianshan Mountains of Xinjiang, similar to the results previously reported for Xinjiang. The low fixation index (Fst) ranged from negative values (Gansu Province) to 0.30346 (Mongolia), indicating that the genetic differentiation between the East Tianshan Mountains and Gansu, and Tibet, Xinjiang was relatively low, with frequent gene flow. In this survey, two 'new' haplotypes were identified in the East Tianshan livestock. In addition, two different haplotypes of liver and lung infections were found in one cattle. This survey provides information on the epidemiology and genetic diversity of E. granulosus s.s. in the East Tianshan Mountains of Xinjiang, China.