[Experimental ocular larva migrans infection in mice].

OBJECTIVE To characterize the histologic alterations in the ocular globe of mice infected with eggs of Toxocara canis, during both the acute and chronic stages of the infection. METHOD Performance of an experimental, prospective study in vivo, with right and left ocular globes [using 5 groups of 4 mice in each study; 2 white (A/J) and 2 black (C57/BL)], infected by the intravenous injection of 1000 embrionated Toxocara canis eggs. The mice were sacrificed sequentially post infection (3-180 days), the eyes evaluated by conventional microscopic techniques and the histopathology findings recorded. RESULTS All the mice revealed some degree of ocular damage in one or both eyes. The retina was the most affected layer with edema, hemorrhage and severe degenerative changes seen. Other alterations included inflammation of the cornea, and obliteration of the anterior chamber with fibrinoid material. We also demonstrated changes in the normal histology of the uvea and lens. In only two eyes were segments of larvae found in the retina, and in each instance there was no evidence of an inflammatory reaction around them. CONCLUSION Most of the changes seen were not related to the presence of larval forms, suggesting they were due to the effect of excretion-secretion products during the infective phase.