Phylogeographic structure and historical dispersal of Schistosoma japonicum across East and Southeast Asia

The evolutionary relationships and geographic differentiation of Schistosoma japonicum populations across East and Southeast Asia remain incompletely resolved. This study investigated phylogenetic structure and regional dispersal patterns using mitochondrial genomes and ND1, ND4, and COX3 gene sequences from 84 isolates. Phylogenetic reconstruction revealed clear divergence between S. japonicum and S. sinensium , supporting their distinct evolutionary positions within the Asian schistosome lineage. Comparative analyses further identified pronounced genetic differentiation between Chinese populations and isolates form Taiwan. ND1 sequence comparations demonstrated extremely high genetic identity exceeding 99% among strains from China, Japan, Indonesia, and the Philippines. These results indicate strong genetic continuity among geographically distant populations despite wide regional separation. Phylogeographic patterns support a mainland Chinese origin followed by historical dispersal toward Japan and Southeast Asian archipelagos. These findings provide new insights into the evolutionary history and regional dissemination pathways of S. japonicum across East and Southeast Asia.