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
Frequently asked questions
What is Toxocara species?
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.
What are the lab clues for Toxocara species?
Lab clues for Toxocara species include Serology (antibody) is the main approach concept, Marked eosinophilia, and No eggs in human stool (larvae do not mature).
What is Toxocara species commonly confused with?
Toxocara species is commonly confused with Ascaris lumbricoides and Trichinella spiralis.
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.