INFECTIOUS DISEASES OF MICE 419 



ences, it is difficult to reconcile the identity of the two organisms because 

 of the morphological appearance of the spores of B. piliformis, the failure of 

 this organism to grow in serum-enriched media on numerous attempts, and 

 the persistence of infective material in a contaminated cage for a year. 



Infection Due to Bartonella, Eperythrozoon and Grahamella 



Three types of organisms which parasitize red blood cells have been 

 found in mice, as well as in other rodents. None produces obvious clinical 

 disease under natural conditions. Infection with two of them, Bartonella 

 and Eperythrozoon, remains latent until manifested by splenectomy, expo- 

 sure to x-ray, or infection with an unrelated agent. The grahamellae, on 

 the other hand, are less notably affected by such events. In Table 4 are 

 summarized the chief characteristics of these three organisms. 



The exact classification of these organisms has been subject to con- 

 siderable doubt and disagreement. Bartonellae and eperythrozoa have 

 been thought by some to be protozoa, by others to be bacteria or Rickettsia- 

 like organisms. Certain authors, in addition, have considered the graha- 

 mellae to be basophilic granulations in the erythrocytes. Although final 

 classification cannot yet be made, it seems probable that the organisms are 

 closely related to bacteria in view of their morphology and behavior. An 

 excellent review of bartonella and eperythrozoon infections up to 1935 may 

 be found in the monograph by Weinman (331). 



Infection with Bartonella. — Bartonellosis as a disease is perhaps best 

 known in man (Oroya fever) and in the rat (infectious or "pernicious" 

 anemia of rats), but it occurs in many other species of animals, especially 

 in small rodents (164, 331, 333). Bartonellae or bartonella-like organisms 

 have been reported in splenectomized white mice (185, 238, 171, 239, 63, 

 121, 167, 60), white-footed deer mice, Peromyscus leucopus (296), and wood 

 mice, Mus sylvaticus (34) . Infection has also occurred following the inocula- 

 tion of mice with trypanosomes (164, 156), although it is not clear whether 

 the strains so obtained had their origin in the mouse or were introduced 

 with the trypanosomes. In spite of the fact that some investigators (303, 

 157, 158, 155) have apparently found spontaneous infection in mice with 

 considerable consistency, the condition must be rare, if not absent, in many 

 mouse stocks. In a combined series of over 100 splenectomized mice (165. 

 2, 302, 298), no bartonellae were found. 



The natural disease. — No instances of spontaneous clinical disease have 

 been reported in mice, although on rare occasions bartonellae may be seen 

 in the blood of naturally infected animals (171). Following splenectomy, 



