RESUMO
Four hundred laboratory bred male Swiss strain albino mice, seven to ten weeks old, were experimentally used to determine the effective mode of immunization against T. spiralis infection. In this regard, active immunization using repeated injection of T. spiralis muscle larval antigen was used in comparison with three, commonly used immunosuppressive drugs (Kenacort, Endoxan and Cyclosporin). Also, the minimal oral dose of T. spiralis larvae that can cause the infection was estimated. The use of T. spiralis muscle larval antigen was found promising for vaccination against the spiralis infection. Although Cyclosporin has an immunosuppressive effect, yet it has a direct lethal effect on both adult and larvae of T. spiralis, and being recommended for treatment of trichinosis. The minimal oral dose of T. spiralis larvae that lead to formation of adult worms in the intestine and larvae in muscles was 20 larvae/mouse. Meanwhile, neither adults nor larvae were formed below this dose.