FAMILY IV. ANAPLASMATACEAE 



983 



three or four organisms may be seen in the 

 same red blood cell. During the height of 

 the reaction, as many as 15 per cent or more 

 of the erj^throcj'tes may be parasitized. Re- 

 sponsible for anemia and icterus. When ane- 

 mic changes progress, the number of in- 

 fected erythrocj-tes decreases to a point 

 where they cannot be demonstrated micro- 

 scopically. Recovery is usually followed by 

 the reappearance of the organisms in rela- 

 tively small numbers for a period of from 

 10 to 30 days and sometimes even longer. 

 The life cycle of A. centrale is in all proba- 

 bility the same as that of A. marginale. No 

 attempts have yet been made to study the 

 life cycle of A. centrale in the arthropod 

 vector. 



Cultivation: No attempts have been 

 made . 



Filterability: No information available. 



Immunology: No authentic case of true 

 natural immunity in cattle has been estab- 

 lished. Acquired immunity occurs in (1) the 

 latently infected ox, (2) the infected ox 

 after splenectomy and recovery from dis- 

 ease, the period of resistance corresponding 

 to the duration of latency, (3) the non- 

 splenectomized, non-carrier ox following in- 

 fection, and (4) animals other than the ox 

 following infection. Recovered animals re- 

 main carriers for periods of up to 20 years. 

 A partial cross immunity exists between 

 this organism and A. marginale. A. centrale 

 has been emploj^ed on the African continent 

 and in Palestine as an immunizing agent 

 against A. marginale. Approximatel}- 350,000 

 doses of A. centrale vaccine (infective cit- 

 rated blood) are issued annually to farmers 

 in South Africa. No cases of autosteriliza- 

 tion have been observed. 



Serology: No work attempted. 



Pathogenicity: Infected blood and organ 

 suspensions produce infection by the sub- 

 cutaneous, intramuscular and intravenous 

 roiites. A. centrale is infectious for cattle. 

 The African antelope, the blesbuck (Dama- 

 liscus pygargus albifrons), develops a sub- 

 microscopic infection. 



Antibiotic therapy: No information avail- 

 able. Aureomycin and terramycin may pos- 

 sibh' be as effective for .4. centrale as for ^4. 

 marginale. 



Source: Observed in the blood of infected 

 cattle. 



Habitat: Found in the arthropods Bo- 

 ophilus decoloratus and Haemaphysalis cin- 

 naharina punctata; also found in the erythro- 

 cytes of cattle. Found in Africa, Roumania 

 and Palestine. 



3. Anaplasma ovis Lestoquard, 1924. 

 (Bull. Soc. path, exot., 17, 1924, 784.) 



o'vis. L. noun ovis the sheep. 



In blood smears fixed with May-Griin- 

 wald and stained with Giemsa, the organ- 

 isms appear in the red blood cells as irregu- 

 larly spherical, chromatic granules which 

 stain a deep purple color. Vary from 0.4 to 

 0.8, averaging 0.5, micron in diameter. Re- 

 sembles A . marginale very closelj- but differs 

 from the latter by its pathogenicity and by 

 its position in the erythrocytes. Approxi- 

 mately 65 per cent of the organisms are sit- 

 uated at or near the margin and 35 per cent 

 at or near the center of the erythrocyte. 

 Occurs singly in the red blood cells, but 

 double forms are not uncommon. Rarely 

 three or four organisms may be seen in the 

 same cell. During the height of the reaction, 

 as many as 5 per cent or more of the eryth- 

 rocj^tes may be parasitized. Responsible for 

 anemia and icterus. When anemic changes 

 progress, the nvmiber of infected erythro- 

 cytes decreases to a point where they cannot 

 be demonstrated microscopically. Recovery 

 is usuallj' followed by the reappearance of 

 the organisms in relatively small numbers 

 for a period from 10 to 30 days and some- 

 times even longer. The life cycle is in all 

 probability the same as that of A. marginale. 

 No attempts have j^et been made to studj' 

 the life cycle of this organism in the arthro- 

 pod vector. 



Cultivation: No attempts have yet been 

 made. 



Filterability: No information available. 



Immunology: No authentic case of true 

 natural immunity in sheep or goats has been 

 established. Acquired immunity occurs in 

 (1) latently infected sheep and goats, (2) 

 the infected sheep and goat after splenec- 

 tomy and recoverjr from the disease, the 

 period of resistance corresponding to the 

 duration of latency, (3) the non-splenecto- 



