Genetic diversity and population structure of Oncomelania hupensis in Sichuan Province, China:implications for schistosomiasis control

Schistosomiasis, caused by the infection with Schistosoma japonicum, remains a significant public health concern in China. As the sole intermediate host of S. japonicum, the breeding and spread of Oncomelania hupensis contribute significantly to the potential risk of disease occurrence and transmission. Exploring the population genetics of the snail vector is conducive to better understanding its distribution and dispersal patterns, and provides more data for future snail surveillance and control from a molecular perspective. The genetic diversity and population structure of O. hupensis in Sichuan Province were evaluated based on sequencing of mitochondrial cytochrome c oxidase subunit 1. A total of 215 snail isolates were collected from 30 counties, identifying 80 haplotypes with high nucleotide diversity (0.05871±0.00160) and haplotype diversity (0.979±0.003). Phylogenetic analysis and haplotype network construction identified five distinct clades. Notably, clade 1 was confined within the Panxi region, while clade 5 exhibited a widespread distribution across the studied areas, distinct from the other four clades, but showing a close genetic relationship to individuals from Yunnan. Spatial differentiation was revealed by significant pairwise genetic distance values detected in 313 out of 435 population pairs, ranging from 0.07632 to 1.00000. Analysis of molecular variance (AMOVA) showed that the majority of variance occurred among populations, but significant differences were also observed among landscape groups. AMOVA also provided support for clade separation by exhibiting significant genetic differences among the clades, which explained 78.23% of the overall variation. Geographical distance and precipitation were found to display a significant correlation with the genetic differentiation pattern of O. hupensis in both Mantel and partial Mantel tests. Temporal stability was observed over sampling intervals of 7 years, particularly among snail populations inhabiting the Panxi area, despite prolonged molluscicide treatment. This study provides updated insights into the genetic diversity and population structure of O. hupensis in Sichuan Province, which contribute to a better understanding of the challenges faced in snail control. In light of the findings, the integration of molecular insights into snail monitoring and control, and the reinforcement of collaborative efforts in neighboring regions, in addition to long-distance monitoring, are suggested.