Relationship between parasitical inoculum and immunological parameters in experimental toxocariasis.

Swiss female mice were inoculated with different infective doses of Toxocara canis eggs to evaluate the percentage of recuperated larvae in different organs and immunological parameters such as spleen index (SI), liver index (LI) and lung index (LuI) and blood eosinophilia during 3 weeks post infectionem (p.i.) with only one challenge. It was found that T. canis larvae arrived at the liver between 10 and 15 hours p.i. by the food-fishhook technique. When the inoculum was more than 200 eggs, there was a reinvasion of liver and lungs at 504 hours p.i. The larval arrival at the brain was delayed in an inverse relationship to the inoculum but the percentage of recovery was about 7 and 8%. The organic indexes were in a direct relationship with the inoculum size and the increase in eosinophilic levels in massive infections (2000 eggs) was in agreement with a strong immune response.