THEILERIA PARVA 



179 



produce the disease in a healthy animal by blood inoculation, but 

 only by intraperitoneal transplantation of large pieces of infected 

 spleen (Meyer). There may be as many as eight parasites in a cor- 

 puscle. The chromatin is usually at one end of the organism. In 

 some parasites the appearance of the chromatin suggests division, but 

 such division, if it takes place, must be very slow, as it has not been 

 actually seen in progress. The red blood corpuscles appear merely to 

 act as vehicles for the parasites (Nuttall, Fantham, and Porter). 1 



13 



14 



FlG. 92. Tkeileria parva. 1-12, intracorpuscular parasites, stained. (After Nuttall and 

 Famham) ; 13-18, K>ch's blue bodies, from stained spleen smear; 17-18, breaking up of 

 Koch's body. (After Nuttall.) 



In the internal organs, especially the lymphatic glands, spleen and bone-marrow, 

 are found multinucleate bodies known as Koch's blue bodies (fig. 92, 13-18}. These 

 are schizonts, according to Gonder. 2 The actual Koch's blue bodies are said to be 

 extracellular, but similar multinucleate bodies, schizonts, occur in lymphocytes. The 

 schizonts divide and the merozoites resulting probably invade the red blood cor- 

 puscles in the internal organs. Gonder considers that the sporozoites injected by 

 the tick collect in the spleen and lymphatic glands, penetrate the lymphocytes and 

 give rise to the schizonts. 



Gonder has studied the cycle of 7 . parva in the tick. He states that the 

 gametocytes leave the host corpuscles and give rise to gametes, then conjugation 

 occurs producing zygotes. The zygotes are then said to become active to form 

 ookinetes, and to enter the salivary glands of the tick. Multiplication is said to 

 occur therein, producing a swarm of sporozoites. This work needs confirmation. 



T. parva is transmitted by Rhipicephalus appendiculatus, R. simus, R. evert si, 

 R. nitens, and R. capensis. The parasites are not hereditarily transmitted in 

 Rhipicephalus, but when taken by the transmitter at one stage of its development 

 the tick is infective in its next stage (e.g., if the larva becomes infected, then the 

 nymph is infective; if the nymph becomes infected, then the adult is infective). 



An animal recovered from Theileria parva is incapable of infecting ticks, but few 

 animals recover from East Coast fever. Animals suffering therefrom do not show 

 haemoglobin uria. 



1 Parasitology, ii, p. 325 ; iii, p. 117. 



- Zeitschr.f. Infekt. paras. Krankh. n. Hyg. d. Haustiere, viii, p. 406. 



