Distribution of Toxocara cati larvae in experimentally infected BALB/c mice

The experimental infection of mice with Toxocara cati provides one of the best models for pathological and immunological study of the visceral larva migrans syndrome. To broaden our knowledge of T. cati larval migration, BALB/c mice were inoculated with 500 embryonated eggs of T. cati for a period of two months. In the present study, T. cati eggs, obtained from faeces of naturally infected cats, were used for infection. After oral infection of 500 embryonated eggs of T. cati, mice were euthanised at 1, 2, 3, 7, 14, 21, 28, 35, and 70 days post-infection (dpi) in groups of three per day. Systemic cytokine patterns of Th2 cytokines were evaluated 1 and 2 months after the experimental challenge using sandwich ELISA. The mean number of larval recovery from all infected mice was 16.53 % during infection. The highest number of larvae was obtained from the liver at 1 and 2 dpi; from lungs at 2 dpi and from the brain at 28 dpi. In muscles, the highest recovery rates of T. cati were obtained at 28 dpi. Our data showed that experimental infection with T. cati induced Th2 responses during the infection. In addition, IL-4, IL-5, and IL-10 levels increased significantly in the sera of the infected mice compared to the control group. Larval persistence of T. cati in the muscle of BALB/c mice and its migration behaviour highlights the important role of mouse as a paratenic host in the parasite life cycle and the host-parasite relationships, especially in human toxocariasis.