Typhus Rickettsia Isolated from Mice and Mouse-Fleas During an Epidemic in Peiping. ∗

It is now generally recognized that “endemic” or murine typhus has its reservoir in rats and is transmitted to man by rat-fleas, particularly Xenopsylla cheopis. 1 , 2 However, in South Queensland, Australia, circumstantial evidence strongly incriminates mice, rather than rats, as the reservoir, although actual proof of infection among these rodents or their ectoparasites is as yet lacking. 3 , 4 Lépine and Lorando, 5 , 6 in Athens, examining rats as well as mice trapped in the premises where cases of typhus had occurred, found that whereas rats were frequently infected with typhus Rickettsia, mice were uniformly free from the infection. Sparrow, 7 on the other hand, recovered 2 typhus strains from the pooled brain emulsions of 10 out of 300 mice (Mus muscidus gentilis) caught at random from different households in Tunis. Brigham 8 also obtained a typhus strain from a field-mouse (Peromyscus polionotus poliomotus) in the rural district of southern Alabama where cases of typhus had developed under conditions which made the rat a “highly improbable causative factor.” It is clear from the above reports that hitherto the association of typhus-infected mice and mouse-fleas with the disease in man has not been conclusively demonstrated, and hence the role of mice as another reservoir of “endemic” typhus can not be considered as settled.