The anatomy of the third-stage larva of Toxocara canis and Toxocara cati.

This review describes the morphology and ultrastructure of the third-stage larva of Toxocara canis, the larval stage that hatches from the egg and persists in the tissues of various paratenic hosts including infected humans. This larva remains unchanged as it passes from host to host and lives for extended periods in this same body form until it makes its way to the gastro-intestinal tract of its final host. There has been less work on the anatomy and ultrastructure of the larva of Toxocara cati, but overall, it appears very similar to that of T. canis with the only apparent difference being that the larva is a few microns thinner in diameter. The paper describes the anatomy and ultrastructure of the larva and the various major structures of the various body systems including the cuticle, hypodermis, the nervous tissue, oesophagus and the lumen-free intestine, and the large excretory gland cell that fills much of the pseudocoel and which appears to be the source of the components that are recognized immunologically by the infected host. It is suggested that further detailed studies on the larva could provide significant information that would allow a greater understanding of how the larva persists within these hosts and may provide information that would make the larva an excellent link to work on nematode anatomy that would link the work being done with this model system to that of Caenorhabditis elegans and the large amount of historical work already performed on adult ascaridoid nematodes.

Comparative in vitro effect of artemether and albendazole on adult Toxocara canis.

Since the integrity of Toxocara canis cuticle is essential for the nutritive and protective functions, light and scanning electron microscopic studies were undertaken to assess, for the first time, whether artemether had any effect on the cuticle including lips and sensory organs following 24 and 48 h incubation in vitro. The results were compared with those observed in the worm cuticle following incubation in albendazole, as it was 100% effective against adult nematode. The body cover changes seen after in vitro administration of artemether were similar to that induced by albendazole sulfoxide, active form, (ABZ-SO). However, the earlier onset of those changes was recorded with the former. The swollen appearance of the anterior end of T. canis, including the lips, distortion of some sensory papillae, and appearance of a number of lesions on the lips, were observed during in vitro action of artemether. Cuticular disruption had also been observed in adult T canis exposed to ABZ-SO. The surface changes were more severe than those observed following incubation in artemether, with which limited loss of the cuticle occurred in the lips of nematode but was not as widespread as that seen with ABZ-SO. However, the cuticular swelling of the anterior end of T canis was more pronounced than that with ABZ-SO. In the present study, artemether presented itself as a drug that might become important in nematode chemotherapy, besides its broad spectrum of activity against various trematodes.

[Toxocara canis (Nematoda) and toxocariasis of animals and humans]. / Toxocara canis (Nematoda) oraz toksokarozy zwierzat i czlowieka.

Some aspects of dog toxocarosis and syndrome of visceral larva migrans in human toxocarosis, particularly in children were presented. In detail the morphological characters and biology of Toxocara canis, its pathogenicity, ways of invasions as well as conditions favouring the spreading of parasites were discussed. Attention was paid to the efficacy of diagnosis of invasions, treatment and prophylaxis. The current toxocarosis threat was analysed and epidemiological prognosis was moved forward.