THE HEMOFLACELLATES 



63 



T. theileri is relatively large, being 

 ordinarily 60 to 70 ;i long, but forms up 

 to 120jLi long and smaller ones 25|i long 

 often occur; those found by Levine et al. 

 (1956) in an Illinois heifer were 34 to 40 /i 

 long exclusive of the flagellum. The pos- 

 terior end is long and pointed. There is 

 a medium -sized kinetoplast some distance 

 anterior to it. The undulating membrane 

 is prominent, and a free flagellum is pres- 

 ent. Both trypanosome and crithidial forms 

 forms may occur in the blood. Multipli- 

 cation occurs by binary fission in the 

 crithidial form in the lymph nodes and 

 various tissues. 



T. theileri is transmitted by various 

 tabanid flies, including Tabamis and 

 Haeinatopota. It reproduces in the fly 

 intestine by binary fission in the crithidial 

 stage. 



T. theileri is ordinarily non-patho- 

 genic, but under conditions of stress it 

 may cause serious signs and even death. 

 It has caused losses in cattle being im- 

 munized against rinderpest and other 

 diseases, and has occasionally been 

 accused of causing an anthrax-like dis- 

 ease. Carmichael (1939) found masses of 

 T. theileri in the brain of a cow which had 

 died with signs of "turning sickness" in 

 Uganda. 



T. theileri may also be associated 

 with abortion, altho it has not proved that 

 it causes this condition. Levine et al. 

 (1956) found it in an Illinois heifer which 

 had aborted, and Dikmans, Manthei and 

 Frank (1957) found it in the stomach of 

 an aborted bovine fetus in Virginia. Lund- 

 holm, Storz and^McKercher (1959) found 

 it as a contaminant in a primary culture 

 of kidney cells from a bovine fetus in 

 California. This was further evidence 

 that intrauterine transmission may occur. 



Ristic and Trager (1958) found T. 

 theileri in three Florida dairy cattle with 

 depressed milk production; it was not 

 found in cows in the same herd with nor- 

 mal milk production. The affected cows 

 had a marked eosinophilia. 



Since T. theileri is rarely seen in 

 the blood, diagnosis ordinarily depends on 



cultivation. It can be cultivated in NNN 

 and other media at room temperature. 

 Ristic and Trager (1958) also cultivated 

 it at 37"" C in a blood-lysate medium. 

 Both crithidial and trypanosome forms 

 were present in their cultures. Lundholm, 

 Storz and McKercher (1959) found that it 

 grew well in tissue culture medium con- 

 taining 10% lamb serum, but better if 

 bovine kidney cells were present. 



No treatment is known for T. theileri. 

 Infections can be prevented by elimination 

 of the tabanid vectors. 



TRYPANOSOMA MELOPHAGIUM 

 (FLU, 1908) 



This parasite is very common in sheep 

 thruout the world. It is non-pathogenic, 

 and infections are so sparse that it can or- 

 dinarily be found only by cultivation. The 

 trypanosomes in the blood resemble T. 

 theileri and are 50 to 60 |i long. 



T. nielophagimn is transmitted by the 

 sheep ked, Melophagns oviuiis, and can 

 readily be found in its intestine. Its life 

 cycle has been described by Hoare (1923). 

 Crithidial forms are abundant in the mid- 

 gut, and leishmanial forms occur here 

 also. Both multiply by binary fission. 

 The crithidial forms change into small, 

 metacyclic trypanosome forms in the hind- 

 gut. Nelson (1956) found that T. melo- 

 phagiiim may kill the ked by blocking the 

 midgut. Sheep are infected when they 

 bite into the keds and the trypanosomes 

 pass thru the intact buccal mucosa. Be- 

 cause infections in sheep are so sparse, 

 it has been suggested that no multiplication 

 occurs in this host. 



TRYPANOSOMA THEODORI 

 HOARE, 1931 



This non- pat ho genie species was 

 found in goats in Palestine. It resembles 

 T. melophagiHui and has a similar life 

 cycle, except that its intermediate host 

 is another hippoboscid fly, Lipoptena 

 capriiia. T. tJieodori may be a synonym 

 of T. nielophagiuni. 



