64 



THE HEMOFLACELLATES 



TRVPAXOSUMA NABIASI 

 RAILLIET, 1895 



This species occurs in the wild 

 European rabbit, Oryctolagns cuniculiis. 

 It has been found sporadically in England, 

 France and other European countries. It 

 is 24 to 28 fi long. Its intermediate host 

 is the flea, Spilopsyllus cuniculi, in which 

 it develops in the gut. The metacyclic 

 infective forms occur in the rectum. In- 

 fection is presumably by ingestion. Grewal 

 (1956) described its life cycle briefly. 



TRYPANOSOMA LEWISI 



CKENT, 1880) 



LAVERAN AND MESNIL, 



1901 



This species occurs quite commonly 

 in the black rat, Norway rat and other 

 members of the genus Ralliis thruout the 

 world. It is not normally transmissible 

 to mice. It is 26 to 34 ^t long. Its vector 

 is the rat flea, Nosopsyllus fasciatus, in 

 which it develops in the gut, and in which 

 the metacyclic, infective forms occur in 

 the rectum. Rats become infected by 

 eating infected fleas or flea feces. T. 

 lewlsi is non-pathogenic. 



A great deal of research has been 

 done on this species, since it is easy to 

 handle and its host is a convenient one. 



TRYPANOSOMA DUTTONI 

 THIROUX, 1900 



This species occurs in the house 

 mouse and other species of Alus thruout 

 the world. It is not normally transmis- 

 sible to rats. It is 28 to 34 ^ long. Its 

 vector is the flea, Nosopsyllus fasciatus, 

 and its life cycle is the same as that of 

 T. lewisi. It is non-pathogenic. 



TRYPANOSOMES OF BIRDS 



Trypanosomes have been reported 

 under a large number of names from 

 many species of birds. They all look 

 very much alike and probably belong to 

 relatively few species. However, exten- 



sive cross transmission studies are 

 needed to establish their relationships, 

 and, until these are carried out, it is 

 probably best to refer to them by the names 

 under which they were first described. 



Trypanosoma avium Danilew sky, 1885 

 was first described from owls (scientific 

 name not given) and roller-birds {Coracias 

 garrulus) in Europe, and has since been 

 reported from a wide variety of birds, in- 

 cluding crows (Baker, 1956) and Canada 

 geese (Diamond and Herman, 1954). Baker 

 (1956 a, b) transmitted it from the rook 

 [Corvus frugilegns) and jackdaw (C. mone- 

 dula) to canaries, but failed to transmit it 

 to a single 3-day-old chick. 



T. calmettei Mathis and Leger, 1909 

 was described from the chicken in south- 

 east Asia; it is about 36 |i long. T. gal- 

 linarum Bruce et al. , 1911 was described 

 from the chicken in central Africa; it is 

 about 60 /i long. T. Iiannai was described 

 from the pigeon, and T. numidae from the 

 guinea fowl. 



Avian trypanosomes are very poly- 

 morphic, sometimes attaining great size. 

 They may be 26 to 60j:x long or even longer. 

 The kinetoplast is generally a long distance 

 from the posterior end. There is a free 

 flagellum, and the body is often striated. 



Blood-sucking arthropods such as 

 mosquitoes and hippoboscids are believed 

 to be the vectors of avian trypanosomes, 

 but the only complete life cycle was worked 

 out by Baker (1956, a, b) for T. avimn from 

 rooks and jackdaws. He found that in Eng- 

 land the hippoboscid fly, Oniilhoiiiyia 

 avicularia, acts as the vector. Upon in- 

 gestion with a blood meal, the trypanosomes 

 change into the crithidial form in the mid- 

 gut, multiply by binary fission in this form, 

 and pass to the hindgut. They multiply fur- 

 ther and then turn into a piriform stage 

 which develops in turn into a small, meta- 

 cyclic trypanosome form. Birds become 

 infected when they eat infected insects. 

 The metacyclic trypanosomes penetrate 

 the membranes of the mouth, esophagus 

 and/or crop and probably invade the lymph- 

 atic system, developing into large forms 



