Genetic diversity and evolutionary relationships of human-derived Ascaris spp. based on mitochondrial markers

Ascaris species are common soil-transmitted helminths infecting both humans and pigs. It is recognized as one of the Neglected Tropical Diseases and is currently targeted in global eradication initiatives. This study employed mitochondrial 'NADH dehydrogenase subunit 1 NAnad1) and Cytochrome Oxidase 1 (cox1) gene' sequences comprising newly generated and publicly available data to investigate the genetic diversity, evolutionary relationships, and potential zoonotic transmission between Ascaris lumbricoides and Ascaris suum. Phylogenetic analysis revealed distinct clustering, with Indian A. lumbricoides sequences showing close genetic affinity to Chinese and Brazilian sequences (Human and Pigs), indicating possible historical gene flow. This genetic relatedness indicates the presence of intra-species variability and supports earlier evidence of potential hybridization between A. lumbricoides and A. suum. Haplotype network analysis based on nad1 identified 27 haplotypes, including both shared and unique variants. Hap₁ and Hap₂ were widely distributed, while several Indian haplotypes were distinct, suggesting localized diversification or genetic divergence. Cox1-based analysis identified 25 haplotypes, with human sequences forming both global and region-specific clusters, and pig-derived A. suum sequences forming a separate clade. These results highlight substantial genetic diversity and underline the importance of molecular surveillance in understanding Ascaris transmission and zoonotic risk.