Effect of Behavior on Development of Resistance in Trichinosis. ∗

Summary

The demonstration that behavioral factors cause hypertrophy of adrenals, and that injection of corticoids decreased the resistance of mice to Trichinella spiralis suggested that behavior might affect infections under relatively natural conditions. “Wild” strain house mice were infected with embryonated larvae. Twelve mice were isolated in jars and 12 were placed in 2 groups in a large can for 3 hours a day for 10 days. When killed on the fifteenth day the grouped mice had from 16–51 worms in the intestine while only 3 of the isolated mice had worms. To determine the effect on subsequent stages, 12 mice were infected. Six were isolated and 6 were grouped for 10 days. All were killed on the thirtieth day. The isolated mice averaged 1054 larvae per gram of muscle while the grouped mice averaged 1556. It is concluded that behavior may affect resistance and it is suggested that this phenomenon may be an important factor in epidemics and in development of host-parasite relations.