SUSCEPTIBILITY OF DIFFERENT STRAINS OF MICE TO VARIOUS LEVELS OF INFECTION WITH THE EGGS OF TAENIA-TAENIAEFORMIS

Susceptibility of different mouse strains to varying levels of T. taeniaeformis eggs was studied. C3H are shown to be susceptible to any quantity of eggs. C57 and NMRI are only susceptible to 1-2 eggs, while larvae from an infection of 30-50 eggs are precociously destroyed. Sometimes fertile larvae can also develop in resistant strains of mice infected with some hundred eggs. In C3H the challenge larvae are unable to survive even from an infection given 24-48 h post-1st inoculum. The hypothesis is proposed that in resistant strains, infection with 30-50 eggs induces a more rapid immune response which becomes effective while the larva is still vulnerable; in massive infections, immune paralysis may occur. Although susceptible strains allow primary infections to develop, they show resistance to challenge infections because larvae are destroyed before they become insusceptible to host attack.