FAMILY IV. ANAPLASMATACEAE 



981 



Genus I. Anaplasma Theiler, 1910* 



(Rept. Govt. Vet. Bact. for 1908-09, Dept.Agr., Transvaal, 1910, 7-64; alsoseeTrans- 



vaal Med. Jour., 5, (January) 1910, 110; Bull. Soc. path, exot., S, (March9) 1910, 



135; and Trans. Roy. Soc. So. Africa, 2, (October 27) 1910, 69.) 



A.na.plas'ma. Gr. prefix an- without; Gr. noun plasma anything formed or molded 

 M.L. neut.n. Anaplasma a thing without form. 

 Description same as for the family. 

 The type species is Anaplasma marginale Theiler. 



Key to the species of genus Anaplasma. 



I. Cause infections in cattle. 



A. The etiological agent of malignant anaplasmosis of cattle. 



1. Anaplasma marginale. 



B. The etiological agent of benign anaplasmosis of cattle. 



2. Anaplasma centrale. 

 II. Causes anaplasmosis of sheep and goats. 



3. Anaplasma ovis. 



1. Anaplasma marginale Theiler, 1910. 

 (Theiler, Rept. Govt. Vet. Bact. for 1908-09, 

 Dept. Agr., Transvaal, 1910, 7; Anaplasma 

 theileri Cardamatis, 1911; Anaplasma argen- 

 linum Lignieres, Cent. f. Bakt., I Abt., 

 Orig., 7^, 1914, 133; also see 10« Congres in- 

 tern, de M^d. Vet., Londres, 1914; Ana- 

 plasma rossicum Yakimov and Beliawine, 

 Cent. f. Bakt., I Abt., Orig., 103, 1927, 419.) 



mar.gi.na'le. L. noun margo, marginis 

 edge, margin; M.L. adj. marginalis mar- 

 ginal. 



In blood smears fixed with May-Griin- 

 wald and stained with Giemsa's stain, this 

 organism appears in the erythrocytes as one 

 or more chromatic granules which stain a 

 deep purple color. Varies in size from 0.3 to 

 0.8 micron, averaging about 0.5 to 0.6 mi- 

 cron. Usually round or elliptical in shape, 

 although irregular forms are not uncommon. 

 About 90 per cent of the bodies are situated 

 at or near the margin of the erythrocytes, 

 while 10 per cent are situated at or near the 

 centers of the host cells. DeRobertis and 

 Epstein (Proc. Soc. Exp. Biol, and Med., 

 77 , 1951, 254) have studied the structure of 

 this organism with the electron microscope: 

 the typical organism occurring at the mar- 

 gin of the erythrocyte appears to be con- 

 stituted of a central, undivided mass and 



of peripheral elementary bodies, 170 to 220 

 millimicrons in diameter, of high electron 

 density; in some cases the whole mass of 

 the organism is divided into submicroscopic 

 bodies. Usually occurs singly in the red 

 blood cells, but double forms are not un- 

 common. Rarely three, four, five and even 

 six organisms may be seen in one red blood 

 cell. A halo may sometimes be seen sur- 

 rounding the organism. During the height 

 of the reaction, as many as 50 per cent or 

 more of the erythrocytes may be parasit- 

 ized. Responsible for a variable degree of 

 anemia and icterus. When anemic changes 

 progress, the number of infected erythro- 

 cytes decreases to a point where they can- 

 not be demonstrated microscopically. This 

 phenomenon should be remembered by 

 workers engaged in chemotherapeutic stud- 

 ies, and the disappearance of organisms 

 following the administration of drugs should 

 not, without due consideration, be attrib- 

 uted to the action of the drug. Recovery 

 is usually followed by the asymptomatic re- 

 appearance of the organisms in relatively 

 small numbers for a period varying from 10 

 to 60 days, sometimes even longer. It is gen- 

 erally assumed that in the mammalian host 

 multiplication of these organisms takes 

 place by simple binary fission. Lotze and 



* Prepared by Dr. W. O. Neitz, Department of Agriculture, Division of Veterinary Ser- 

 vices, Onderstepoort, Union of South Africa, December, 1954. 



