The Development of Immunity in Cavies to the Larvae of Cochliomyia americana C & P.*

Abstract

The number of C. americana larvae constituting a maximum sublethal and a minimum lethal initial infestation in the average cavy was found to be 2 and 3, respectively, per hectogram of body weight. The immunity or enhanced tolerance developed in cavies to C. americana larvae from initial maximum sublethal and from 3 reinfestations was detd. The amt. so developed is 50-100% greater than that of uninfested animals and is the result of the initial infestation. No substances deleterious to the larvae were developed by cavies from initial infestations or by as many as 3 reinfestations. In cavies either the extension of a local immunity or the establishing of a systemic immunity by previous infestations of screwworms was demonstrated. There is no indication of enhanced tolerance to C. americana in cavies born of infested parents. Other than a slight retardation of death, no tolerance to C. americana greater than that occurring in normal cavies was produced by injections of sterile suspensions of mature tub-reared C. americana larvae and of Proteus chandleri.