Abstract
Leptopsylla segnis fleas were found to be somewhat more effective in transmitting murine typhus infection to rats in the laboratory than had been the putative vector, Xenopsylla cheopis , as previously reported. The etiological agent, Rickettsia typhi (=R. mooseri) , appeared earlier in the feces of L. segnis than it had in X. cheopis , and the course of infection within the two species was essentially similar, although apparently proceeding at a somewhat accelerated rate in L. segnis . Because rickettsiae appeared in the foregut and proventriculus of L. segnis , it seems probable that this species can transmit the infection by bite, as has been recently shown for X. cheopis . Rickettsial development was appreciably more rapid under ambient conditions of 24°C than at 18°C. The role of L. segnis as a potential vector of murine typhus, at least among murid hosts, should be reconsidered.