Studies on Experimental Shigellosis

Abstract

Rats, mice, and other small rodents under natural conditions are refractory to disease of Shigella etiology. A previous publication in this series has described the symptoms and pathology which occurred in normal laboratory albino mice experimentally infected with Shigellaflexneri 3 (1).Experiments to be described in the present paper illustrate the effect of fasting and fatigue on the response of albino mice to experimental Shigella infections. In these experiments the response of the host has been estimated on the basis of the mortality rate among infected animals, on the persistence of the organisms in the intestine, and on the occurrence of bacteriemia in the experimental host. Materials and MethodsThe routine methods and materials employed in this study were the same as those described in an earlier publication (1). EXPERIMENTAL AND RESULTS The Effect of Fasting on Shigdla Infections in Mice.--Mice were fasted by withdrawing all food from their cages, but allowing free access to water. The cages were constructed of woven wire which denied the animals access to fecal droppings. In a few instances weaker animals were killed by their cage mates, or died before the completion of the fasting period. Mice were not used ff any deaths occurred among cage mates during the prefasting period. Fasted and non-fasted mice were used in parallel experiments to determine the LDso of S. flexnezi 3.The results presented in Table I indicate that the intraperitoneal and rectal LDs0 of Shigetla decreased as the length of fasting time increased. However, the oral LDs0 for fasted animals was larger than for normal animals. This is * The opinions or assertions contained herein are the private ones of the writers and are not to be construed as ofllcial or reflecting the views of the Navy Department or the naval service at large. ~/Present