Disseminated ascariasis infection with encephalopathy: Molecular confirmation and phylogenetic insights.

Ascariasis remains a major parasitic infection in low-resource regions, with children at highest risk. We describe a rare and severe pediatric case from rural Colombia involving intestinal obstruction, peritonitis, cholecystitis, and encephalopathy. A recovered helminth underwent stereoscopic examination and molecular characterization through amplification of 18S-rRNA and COII genes, followed by long-read sequencing using Oxford Nanopore technology. Taxonomic analysis with Centrifuge and BLAST confirmed the specimen as Ascaris, showing high similarity to Ascaris suum, while COII phylogenetics clustered it with Ascaris lumbricoides. The sequence formed a monophyletic group with Ascaris suum, Ascaris lumbricoides, and Parascaris spp., suggesting potential hybridization or cryptic diversity within Ascaris. The child required surgical management, albendazole, and supportive care including ECMO, ultimately recovering without neurological sequelae. This case highlights the zoonotic potential and extremely rare neurological manifestations of Ascaris infection and demonstrates the diagnostic value and challenges of long-read sequencing in resolving complex taxonomic relationships.