up to 2.5 microns also occur. This is per- haps the largest species in the genus. Cultivation has not been successful. Immunologj^: Latent infection made man- ifest by splenectomy; under field condi- tions, animals with spleen sicken and pre- sent massive infections. Pathogenicity: Implicated in "ictero- anemia" of swine, heavy infection and dis- ease being provoked without splenectomy. Has not infected one or more of: lamb, calf and the following splenectomized animals: white mouse, deer mouse (Peromyscus man- iculatus), rats, guinea pigs and rabbits. Chemotherapy: Neoarsphenamine, at doses of 15 milligrams per kilogram of pig, is effective in controlling the infection. Source: Occurs in the blood of swine in the United States and perhaps in the Bel- gian Congo. 7. Eperythrozoon parvuni Splitter, 1950. (Science, 111, 1950, 513.) par'vum. L. adj. parvus small. One of the smallest of the eperythrozoa. Disc or coccus forms measuring less than 0.5 micron in diameter predominate and are mixed with occasional ring forms 0.5 to 0.8 micron in diameter. Filterable through Seitz EK and Berkefeld W filters and by this means can be separated from E. suis, which does not pass these filters. Differentiation from E. sids is based on size, on morphological differences and on the failure of either species to cross-immu- nize against the other. Resembles E. dispar in appearance, and the two have not been proved to be distinct. Rarely pathogenic. Has not infected one or more of: calf, lamb, splenectomized white mouse and splenectomized Peromyscus ma- niculatus. Chemotherapy: Relatively resistant to neoarsphenamine in vivo, frequently resist- ing doses of 45 milligrams per kilogram of hog. Source: Found in the blood of swine in the United States. FAMILY IV. ANAPLASMATACEAE PHILIP, Fam. Nov.* {Anaplasmidae Lestoquard, Les piroplasmoses du mouton et de la chevre. Inst. Past. d'Algerie, 1926; also see Yakimov, Handbook of Protozoology, Moscow, 1931; and Neitz, Alexander and du Toit, Onderstepoort Jour. Vet. Sci. and Anim. Ind., 3, 1934, 263.) A.na.plas.ma.ta'ce.ae. Gr. neut.n. Anaplasma type genus of the family; -aceae ending to denote a family; M.L. fem.pl.n. Anaplasmataceae the Anaplasma family. Organisms which parasitize red blood cells. There is no demonstrable multiplication in other tissues. In blood smears fixed with May-Griinwald and stained with Giemsa's stain, these organisms appear in the erythrocytes as spherical chromatic granules which stain a deep reddish violet color. Show no differentiation into nucleus and cytoplasm. Occur natu- rally as parasites of ruminants. Transmitted by arthropods. Situated at or near the margin and/or at or near the center of the red blood cells. The position within the erythrocyte and/or host differences serve as bases for differentiating species. Attempts at cultivation in a variety of media have failed. Produce disease in non-splenectomized and in splenec- tomized ruminants. The natural and experimental host range is fairly wide, these organ- isms occurring in members of the families Bovidae and Camelidae. Influenced by aureomycin and terramycin. Widely distributed throughout the world. There is a single genus.
- Arranged by Dr. Cornelius B. Philip, Rocky Mountain Laboratory, Hamilton, Mon-
tana, March, 1956; see Canad. Jour. Microbiol, 2, 1956, 269.
