Transmission of Murine Typhus in Roof Rats in the Absence of Ectoparasites

Abstract
The role of rat fleas in the transmission of murine typhus has been established by many investigators (1, 2, 3, 4, 5). Nevertheless, there are references in the literature which state that the urine of typhus-infected rats may be infectious (6, 7). In order to evaluate the possibility of transmission of typhus among rats in the absence of ectoparasites, transmission was attempted by urine and other excreta of infected rats and by fighting and cannibalism among infected and nonimmune rats. MATERIALS AND METHODS Inocula. The Wilmington strain of murine typhus rickettsias was grown in the yolk sacs of fertile eggs (8). Roof rats, Rattus rattus subspp., were infected by intraperitoneal inoculation of 0.5 cc. amounts of a 10-3 dilution of infectious yolk sac. Complement fixation test. The test was a modified Kolmer procedure described in detail elsewhere (9). Two units of soluble type antigen prepared from infected yolk sac were used (10).