Nanopore-based analysis unravels the genetic landscape and phylogenetic placement of human-infecting Trichuris species in Cote d'Ivoire, Tanzania, Uganda, and Laos

Soil-transmitted helminthiases, particularly trichuriasis, affect over 500 million people, mostly in low- and middle-income countries. Traditional diagnostics fail to distinguish between Trichuris species, obscuring transmission patterns and treatment outcomes. Using nanopore-based full-length ITS2 rDNA sequencing, we analyzed 687 samples from Cote dIvoire, Laos, Tanzania, and Uganda, confirming the phylogenetic placement of Trichuris trichiura and the recently described Trichuris incognita. We identified two genetically distinct Trichuris species infecting humans, with divergent geographic patterns and presence in non-human primates, suggesting complex host-parasite dynamics. Within-country genetic variation indicated local adaptation and cryptic population structure. Importantly, we demonstrated that ITS2 fragment length is a robust, cost-effective diagnostic marker for differentiating T. incognita and T. trichiura, offering a practical alternative to sequencing for resource-limited settings. These findings expose the hidden complexity of Trichuris infections and highlight the urgent need to update diagnostic and control strategies to account for overlooked species diversity in endemic regions.