426 BIOLOGY OF THE LABORATORY MOUSE 



were found in the red cells and free in the plasma. No other cause of death 

 was determined, although it is doubtful if an adequate search for other 

 infectious agents was made. 



A strain of Eperythrozoon, termed E. dispar and differing from E. 

 coccoides in morphology and pathogenicity, has been found in field mice 

 (Arvicola arvalis) and dwarf mice {Mus minutus) by Bruynoghe and Vas- 

 siliadis (32, 33, 37), and in the vole by Tyzzer and Weinman (298). No 

 clinical signs or special alterations of the blood were noted. 



Several instances of mixed infection with bartonellae and eperythrozoa 

 have been described (157, 158, 121, 163, 60). In view of the interference 

 which Tyzzer (296) found in white mice between E. coccoides and the deer 

 mouse strain of bartonella, it is interesting to note that Marmorston (163) 

 encountered the same phenomenon in splenectomized mice spontaneously 

 developing infection with natural strains of both organisms. In each of 

 4 animals showing mixed infections, the bartonellae became evident only 

 after the eperythrozoa had disappeared. Moreover, when blood of these 

 animals was injected into young splenectomized mice, only the E. coccoides 

 developed. 



Transmission of E. coccoides from infected to uninfected splenectomized 

 mice by the mouse louse, Polypax serrata, appears to be a natural method 

 of spread (62). Attempts to induce infection by other vectors, by contact, 

 by a deficient diet, and by hereditary transmission have all been unsuccessful 

 (52,63, 167,331). 



Chemotherapy with arsenical compounds is effective in preventing or 

 eliminating infection with E. coccoides (32, 33, 120, 122). 



The experimental disease. — Infections with E. coccoides may be readily 

 transmitted to splenectomized white mice free from the disease by sub- 

 cutaneous or intraperitoneal inoculation of blood from an actively or 

 latently infected mouse (237, 52, 32, 33, 331). The resulting disease is 

 entirely similar to the natural infection. Injection of normal, disease-free 

 mice produces a latent infection which may at any time be activated by 

 splenectomy (331, 163). Reinoculation of chronically infected splenec- 

 tomized mice is without effect (52, 331), but if the organisms are eradicated 

 by arsenical therapy a second inoculation will reproduce the original 

 infection with little or no evidence of immunity (32, 33). Attempts to 

 infect by the oral route have been unsuccessful (331). Citrated blood 

 retains its infectivity for 5 days but not for 10 days at 5°C. (331). 



Inoculation of other species of animals with E. coccoides has given con- 

 flicting results. In normal rats a latent infection, becoming evident after 



