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.
