THE PIROPLASM4lSIDA 



305 



Laird and Lari (1957) assigned this 

 species to the genus Babesia, considering 

 that the differences between the various 

 members of the Babesiidae, including 

 Aegyp/iaiiella. might best be dealt with at 

 the subgeneric level. They may well be 

 correct. However, until more is known 

 about the avian babesiids, I prefer to leave 

 them in the genus Aegyptiaiiella. 



Morphology: The form from the 

 chicken described from Henry (1939) is 

 0.2 to 2. 5 p. in diameter, occurring as 

 Anaplasuia -like granules, as small rings 

 and as elongate bodies with a terminal dot 

 of chromatin and a thin tail of cytoplasm. 

 Both binary fission and schizogony were 

 seen. The nuclei of the schizonts are 

 either strung on a thin cytoplasmic ring 

 or are at the angles of triangular or 

 lozenge-shaped figures. The schizonts 

 usually produce 4 merozoites, altho some 

 have as many as 6. 



The form described by Schurenkova 

 from the eagle produces 4 merozoites and 

 also has large, homogeneous bodies which 

 she took to be gametocytes. 



The form described by Laird and Lari 

 from the crow has anaplasmoid bodies 0.2 

 to 0.6/i in diameter, elongate forms 0.7 

 to 0. 9 by 0, 1 jLt composed of a terminal dot 

 of chromatin and a slender cytoplasmic 

 tail, ring forms measuring up to 2. 1 by 

 1.4(i, and large, solid, oval or irregular 

 forms 0. 9 to 5. 3 [x in diameter. All stages 

 could divide by binary fission. Cruciform 

 and fan-shaped schizonts were also present. 

 Four merozoites are formed. 



The form described by McNeil and 

 Hinshaw (1944) from turkey poults was 

 roundish, oval or piriform, 0. 5 to 2 /j. in 

 diam.eter, and occurred singly or in pairs. 

 They thought it resembled Sauroplasnia 

 tho)}iasi, a blood parasite described from 

 a lizard in South Africa by DuToit (1937). 



Life Cycle : Unknown. 

 Pathogenesis : Unknown. 



FAMILY THEILERIIDAE 



Members of this family are relatively 

 small, round, ovoid, irregular or bacilli- 

 form parasites. They occur in the erythro- 

 cytes and lymphocytes or histiocytes. 

 Schizogony takes place in the lymphocytes 

 or histiocytes, and is followed by invasion 

 of the erythrocytes. The forms in the 

 er3rthrocytes may or may not reproduce; 

 in the latter case they divide into 2 or 4 

 daughter cells. Reichenow (1940, 1953) 

 maintained that schizogony does not occur 

 in the vertebrate host but is simulated by 

 repeated binary fissions. However, ob- 

 servations on the protozoa in tissue cul- 

 ture (Tsur-Tchernomoretz, 1945; 

 Brocklesby and Hawking, 1958) indicate 

 that schizogony does occur. 



The vectors are ixodid ticks. Binary 

 fission, schizogony and sexual reproduction 

 have been said to occur in the tick, but the 

 existence of sexual reproduction is dubious, 

 and Reichenow (1940, 1953) believed that 

 schizogony is simulated by repeated binary 

 fissions. 



Members of this family cause an im- 

 portant group of diseases, known collec- 

 tively as theilerioses, in cattle, sheep 

 and goats. These have caused heavy 

 losses in Africa, southern Europe and 

 Asia. 



This group has been reviewed by 

 Reichenow (1953), Poisson (1953), and 

 most comprehensively by Neitz (1956, 

 1957, 1959). Most authors place all mem- 

 bers of the family in the genus Theileria 

 (e.g., Poisson, 1953), while some accept 

 the genus Cytauxzoon as well (e.g. , 

 Reichenow, 1953). However, Neitz and 

 Jansen (1956) divided the group into 3 

 genera on the basis of biological character- 

 istics. They even placed them in 2 fam- 

 ilies in a new suborder Leucosporidea, 

 but this latter treatment does not seem 

 justified. 



In the genus Theileria as redefined 

 by Neitz and Jansen, the forms in the 

 erythrocytes do not divide, the parasites 

 cannot be transmitted by blood inoculation, 

 and recovered animals do not remain car- 



