Abstract
The latest taxonomy recognizes two Spirometra species in Asia: S. mansoni and S. asiana, with the former exhibiting a global distribution. The isolates analyzed in this study were classified accordingly, and a S. mansoni isolate from India was identified using morphology, Polymerase Chain Reaction (PCR), sequencing, and phylogenetics. Furthermore, a global analysis of genetic diversity, haplotype network structure, and population dynamics of Spirometra spp. was conducted using the 28S rRNA marker. Phylogenetic analysis of Spirometra sequences (n = 104) revealed two distinct clades: a larger clade with Asian (China, Korea, and India) and African (Egypt) sequences (reclassified as S. mansoni) and a smaller clade with European (Latvia and Finland) sequences (true S. erinaceieuropaei). The Asian S. mansoni population showed high haplotype diversity (Hd = 0.821 ± 0.035) and moderate nucleotide diversity (π = 0.00695 ± 0.00054). Asian haplotypes were closely related, with Hap_6 being the most common. The European S. erinaceieuropaei population formed a single haplotype (Hap_15) and exhibited no genetic variation. Population dynamics suggested expansion in global and Asian populations, with strong geographic structuring. The global mismatch distribution indicated a structured population with variable genetic diversity among populations. Genetic differentiation between continents was evident and AMOVA results confirmed that most genetic variation was due to differences among continental populations. This study confirmed S. mansoni in India, clarified its global spread, and provided insights into its population dynamics. The results can inform public health strategies, improve understanding of these zoonotic tapeworms, and help reduce transmission risks to humans.