Analysis of Echinococcus multilocularis complete mitogenomes: evidence for the historical spread from Central Asia to the Northern Hemisphere.

Echinococcus multilocularis is a parasitic tapeworm responsible for alveolar echinococcosis (AE), a life-threatening zoonotic disease. Understanding its genetic diversity and historical spread is critical for developing effective control measures. Previous studies have suggested Central Asia as a potential origin of the parasite, but comprehensive global analyses encompassing multiple regions and time periods have been limited. This study aimed to analyze the genetic diversity, population structure, and phylogeography of E. multilocularis by sequencing the complete mitogenome from 384 isolates from major endemic regions across the Northern Hemisphere. We sequenced 201 new E. multilocularis mitogenomes and combined these with 183 previously published sequences. Phylogenetic, haplotype network, pairwise fixation index (Fst), and principal-component analysis (PCA) were performed to explore genetic diversity, population structure, and the historical spread of the parasite. Bayesian phylogeographic reconstruction was used to infer diffusion routes across the Northern Hemisphere. Our analysis identified five major clades, with high genetic diversity observed in samples from China-Xinjiang and China-Midwest. The parasite exhibited significant genetic differentiation between continents, with most clades tracing their origins to Central Asia. Phylogeographic analysis suggested that E. multilocularis spread from Central Asia to Europe, Japan, and North America, primarily through wildlife migration and human activities. This study supports the hypothesis that Central Asia is the evolutionary origin of E. multilocularis and provides insights into its historical and contemporary dispersal patterns. The findings highlight the importance of monitoring and controlling the spread of human AE, particularly in regions, with high genetic diversity, to prevent further spread.