Johns Hopkins ABX Guide
Toxocara species and Baylisascaris
MICROBIOLOGY
- Toxocara spp.
- Worldwide helminthic infection of humans, agent nematodes:
- Toxocara canis (dog roundworm)
- Toxocara cati (cat roundworm), less common
- Humans are infected as accidental hosts by ingesting eggs from contaminated soil [life cycle Fig. 1] by feces of infected dogs or cats.
- It usually occurs in overcrowded, poor living conditions with dogs or cats.
- Ingested eggs evolve to larval forms penetrating intestinal mucosa with subsequent spread to a variety of body organs (visceral larval migrans [VLM] and/or eyes, ocular larval migrans [OLM]) in arrested development, no ongoing production. Host inflammatory reactions produce symptoms as parasites die off.
- Human infection does not yield egg production; hence inspection of stool O&P is pointless.
- It usually occurs in overcrowded, poor living conditions with dogs or cats.
- Worldwide helminthic infection of humans, agent nematodes:
- Baylisascaris procyonis (raccoon roundworm worldwide, including the U.S.) has also been reported to cause VLM (mainly CNS forms, eosinophilic meningoencephalitis) and OLM.
- Life cycle [Fig 2]
- Note: cutaneous larval migrans (CLM) is caused by several nematodes, most commonly hookworm (Ancylostoma braziliense).
There's more to see -- the rest of this topic is available only to subscribers.
Last updated: February 5, 2023
Citation
Auwaerter, Paul. "Toxocara Species and Baylisascaris." Johns Hopkins ABX Guide, The Johns Hopkins University, 2023. Pediatrics Central, peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540557/all/Toxocara_species_and_Baylisascaris.
Auwaerter P. Toxocara species and Baylisascaris. Johns Hopkins ABX Guide. The Johns Hopkins University; 2023. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540557/all/Toxocara_species_and_Baylisascaris. Accessed July 20, 2025.
Auwaerter, P. (2023). Toxocara species and Baylisascaris. In Johns Hopkins ABX Guide. The Johns Hopkins University. https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540557/all/Toxocara_species_and_Baylisascaris
Auwaerter P. Toxocara Species and Baylisascaris [Internet]. In: Johns Hopkins ABX Guide. The Johns Hopkins University; 2023. [cited 2025 July 20]. Available from: https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540557/all/Toxocara_species_and_Baylisascaris.
* Article titles in AMA citation format should be in sentence-case
TY - ELEC
T1 - Toxocara species and Baylisascaris
ID - 540557
A1 - Auwaerter,Paul,M.D.
Y1 - 2023/02/05/
BT - Johns Hopkins ABX Guide
UR - https://peds.unboundmedicine.com/pedscentral/view/Johns_Hopkins_ABX_Guide/540557/all/Toxocara_species_and_Baylisascaris
PB - The Johns Hopkins University
DB - Pediatrics Central
DP - Unbound Medicine
ER -
