Toxocara canis infection in multiple types of animals: ophthalmological and pathological observations

AbstractHuman ocular toxocariasis (OT), caused by pet roundworm Toxocara canis (Nematoda Ascaridoidea), is a worldwide ocular parasitic infection severe threat to eyesight, especially in school-aged children. However, the infection process and pathological mechanism of Toxocara canis on the ocular are difficult to study in human body. This study was designed to explore long-term ocular manifestation in multiple types of animals infected with Toxocara canis, uncovering the specific pathological mechanism, migration pathway of larvae after infection. Three experinment animals including mice, gerbils and rats were selected and infected with Toxocara eggs, and ocular changes were closely observed and recorded for at least 2 months. The ocular infection rate and mortality tended to be stable at 7 day-post-infection (dpi). At 7dpi, the achievement ratio of mice infected with 2000 T. canis eggs (M2k), gerbils infected with 1000 (G1k), 2000 (G2k) and 4000 (G4k) T. canis eggs were higher, respectively 62.5%, 75%, 100% and 100%. Hemorrhagic lesions, mechanical injury of retina and larval migration can be observed after 3dpi. And the larval tissue, the structure disorder and the inflammation could be observed in the pathological sections. In conclusion, the mice infected with 2000 T. canis eggs and gerbils infected with 1000, 2000, 4000 T.canis eggs represented obvious ocular lesions, could be served for long-term observation.