978 



ORDER I. RICKETTSIALES 



B. Found in the deer mouse. 



2. Eperyihrozoon varians. 



C. Found in the vole and in the dwarf mouse. 



3. Eperythrozoon dispar. 

 II. Not found in rodents. 



A. Found in herbivorous animals. 



1. Found in cattle. 



4. Eperythrozoon wenyonii. 



2. Found in sheep. 



5. Eperythrozoon ovis. 



B. Found in omnivorous animals (swine). 



1. Large, non-filterable and often pathogenic organisms. 



6. Eperythrozoon suis. 



2. Small, filterable and usually non-pathogenic organisms. 



7. Eperythrozoon parvum. 



1. Eperythrozoon coccoides Schilling, 

 1928. (Schilling, Klin. Wochnschr., 7\ 1928, 

 1854; Gyromorpha musculi Dinger, Nederl. 

 tijdschr. geneesk., 72, 1928, 5905.) 



coc.co.i'des. Gr. noun coccus a berry; 

 M.L. noun coccus a coccus; Gr. noun eidus 

 shape; M.L. adj. coccoides coccus-shaped. 



In stained blood films these organisms 

 appear as rings, coccoids and rods, the ma- 

 jority as rings of regular outline wdth clear 

 centers. The proportion of forms appearing 

 as rings varies with the technique employed; 

 if desiccation is prevented, rings occur in 

 minimal numbers (Wigand and Peters, 

 Ztschr. f. Tropenmed. u. Parasitol., S, 

 1952, 461). Measure 0.5 to 1.4 microns in 

 greatest dimension. No limiting membrane 

 and no differentiated internal structure 

 obiserved with the electron microscope. Oc- 

 cur in plasma and on red blood cells. Sug- 

 gested methods of multiplication are binary 

 fission, budding and development of small 

 coccoidal to annular forms. Stain pale red 

 or reddish blue with either the Giemsa or the 

 Maj^-Griinwald-Giemsa technique. Gram- 

 negative. 



Filterability: Reported to pass collodion 

 membranes of an average pore size of 0.36 

 micron (Niven et al.. Lancet, 263, 1952, 

 1061). 



Has not been cultivated. 



Immunology: The immunological state in 

 animals is that of the premunition type. 

 Latent infection in mice is made manifest 

 by splenectomy. 



Pathogenicity: Infects white mice, rab- 

 bits, white rats, wild mice and hamsters 



{Cricetus auratus) ; usually maximal in 

 young animals or in splenectomized adults. 

 Reported to cause fatal mouse hepatitis 

 when associated with another etiological 

 agent (a virus), otherwise moderate to no 

 anemic changes reported. Virus titers are 

 increased one hundred fold in combined in- 

 fections (Niven et al., loc. cit.). 



Antibiotic- and chemo-therapy: Neo- 

 arsphenamine very effective; chlortetra- 

 cycline (aureomycin) and oxytetracycline 

 (terramycin) active; sulphonamides and 

 sulphones show little to no activity. 



Source: Recovered from the blood of 

 splenectomized white mice. 



Habitat: Found in the blood of infected 

 mammals; also found in the mouse louse 

 (Polyplax serrata) and probably in other 

 arthropods. 



2. Eperythrozoon varians Tyzzer, 1942. 

 (Proc. Amer. Philosoph. Soc, 85, 1942, 



387.) 



va'ri.ans. L. part. adj. varians varying. 



Occurs as rings, as coccoids of varying 

 sizes and occasionally as very minute, bacil- 

 lary forms. Many of the bacilliform elements 

 show an unstained, lens-like swelling, in- 

 dicating the formation of a ring within 

 the substance of the rod. At the height of 

 the infection, most of the organisms are 

 found in the plasma. Stain intensely when- 

 ever in contact with a red cell. 



Infectivity: Infective for the gray-backed 

 deer mouse (causing anemia) and for the 

 splenectomized common deer mouse. Not 

 infective for splenectomized white mice. 



