Abstract
It has been known that in the course of their migration, Toxocara canis larvae wander widely through various tissues of the dog. It has also been known, from experimental infections, that some of these larvae are arrested in the course of their migration and remain in visceral tissues unable to either develop or proceed further. These facts were established from digestion experiments, and the effects of the arrested larvae on the host were known in but few tissues. We have found that granulomas form around such larvae, and that these occur in a wide variety of tissues: kidney, liver lung, myocardium, skeletal muscle, thyroid, pancreas, pituitary, lymph node, intestine, retina, brain and cauda equina.
The larvae in the granulomas were identified as Toxocara species, presumably T. canis. The lesions resemble those of human visceral larva migrans, but do not elicit clinical signs. Because they occur in the same host that harbors the adult worm, the previously accepted definition of visceral larva migrans is too narrow, and it is proposed that this term be applied to any visceral lesions produced by migrating helminthic larvae.