Certain aspects of the host-parasite relationship of Nematospiroides dubius (Baylis): IV. The effect of the host's age on experimental infections in the mouse and rat

Abstract

1. The mouse and rat (an abnormal host) show an age resistance towards experimental infections with N. dubius.2. This resistance was complicated by a different reaction in the male and female mouse and rat.3. The rat exhibits age resistance despite being gonadectomized immediately after weaning.4. Gonadectomy with replacement of the homologous sex hormone did not materially alter the age resistance of the host, but the administration of testosterone to the castrated male rat increased the numbers of larvae which penetrated the gut wall. Oestradiol decreased these numbers in the spayed female rat.5. The relationships between the age resistance and the sex resistance of the hosts was discussed.