Parasite
Toxocara species
Dog/cat roundworm causing larva migrans
tok-so-KAR-uh
High-yield clue
Ingesting eggs from soil contaminated with dog/cat feces causes visceral or ocular larva migrans, typically in young children with pica.
Overview
Dog and cat ascarid roundworms (Toxocara canis/cati) whose eggs infect humans as accidental (dead-end) hosts, where larvae migrate but cannot mature, the classic study model for larva migrans.
Classification
- Nematode (roundworm, ascarid)
- Definitive host is dog or cat
- Humans are accidental dead-end hosts
- Larvae migrate but do not mature in humans
Lab & identification clues
- Serology (antibody) is the main approach concept
- Marked eosinophilia
- No eggs in human stool (larvae do not mature)
Associations
- Egg ingestion from contaminated soil/sandboxes
- Visceral larva migrans vocabulary
- Ocular larva migrans vocabulary
- Young children with geophagia/pica
Commonly confused with
- Ascaris lumbricoides
- Trichinella spiralis
Your notes
Original student-study summary. Sources checked: OpenStax Microbiology 2e, NCBI Bookshelf Medical Microbiology, and CDC topic pages where applicable; reviewed 2026-06. Educational only; no diagnosis, treatment, dosing, or specimen-handling guidance.