EYE AND VISCERAL ORGANS PARASITES
NEMATODA Order: Ascaridata

TOXOCARA CANIS

cara1-ic

Toxocara canis: life cycle.

Human toxocariasis is caused by nematodes of the genus Toxocara,
especially T.canis (common roundworm of dogs).

cara2-ic	cara2a-ic

cara2: Toxocara canis: the infection is acquired from ingestion of
embryonated eggs released in the soil.
Eggs measure 75 by 90 µm. 

cara2a: Adult Toxocara canis.

cara2b-ic

Toxocara canis: embryonated egg.

cara3-ic

Toxocara canis: scan microscopy of a T.canis egg.

cara4-ic

Toxocara canis: after ingestion, L2 larvae begin a somatic migration
to the lungs, liver, eye, CNS.

cara5-ic

Toxocara canis: the clinical presentation depends on the number
of larvae ingested and the degree of allergic response.
Two major syndromes have been identified:
Visceral Larva Migrans (VLM) characterized by fever,
malaise, leucocytosis with hypereosinophilia, hepatomegaly,
cough, myalgias, high titers of isohaemagglutinins,
other manifestation include myocarditis, encephalitis and pneumonia;
Ocular Larva Migrans (OLM) caracterized by retinal granulomas and uveitis.
Ocular toxocariasis: posterior retinal granuloma

cara6-ic

Toxocara canis: L2 larvae can be cultured in RPMI 1640 with glutamine 1%.
Larvae maintained in vitro release excretory/secretory (E/S)
antigens used for diagnostic tests.
Larvae may be seen by Tyndall's effect in the square.
Larvae in RPMI medium.

cara7-ic

Toxocara canis: western-blot analysis,

Diagnosis of toxocariasis relies, to date, upon the detection of
antibodies by ELISA or western-blot analysis.
Western-blot stripe: using E/S Ag, 7 bands are seen, splitted into 2 groups.
Positive reaction concerning low molecular bands (from 1 to 4 bands)
is specific for Toxocara infection; banding pattern only including
the high molecular weight (HMW) is evocative of cross-reaction,
especially with strongyloidiasis, pin-worm and Taenia saginata disease.