XVIIl] 



TRYPANOSOMA CONGOLENSE 



351 



Trypanosoma congolense Broden, 1904. 



This parasite, which very closely resembles T. pecorum and 

 T. dimorphon, was first described by Broden, who found it occur- 

 ring in the blood of a donkey and sheep in the Congo Free State. 

 Subsequently the parasite was also observed in the blood of 

 cattle and dromedaries in the same locality and also in cattle, 

 sheep, goats and dogs in the French Congo, where, according 

 to Martin, Leboeuf and Roubaud, it is widely distributed. In 

 North-East Rhodesia, Montgomery and Kinghorn have observed 

 T. congolense in the blood of cattle. It is doubtful whether 

 the trypanosomes occurring in dogs on the shores of Tanganyika 

 should be referred to this species or to T. pecorum. 



T. congolense is only distinguishable from T. pecorum by 

 cross-immunity reactions, for Laveran and Mesnil shewed that 

 a goat immune against T. congolense was susceptible to infec- 

 tion with pecorum. Otherwise the two forms are practically 

 identical and it is questionable whether they should be regarded 

 as distinct species. 



Fig. 78. Culture of T. congolense in the intestine of G. palpalis. ( x about 

 1600). a, h, normal forms from the circulating blood ; i, 2, forms 

 24 hours after ingestion ; 3, 5, forms after 48 hours ; 6, 7, form 5 after 

 56 hours. (After Roubaud.) 



In addition to cattle, sheep, goats and dogs, all the usual 

 experimental animals may be infected with congolense, but 

 the course of the disease is usually very slow, resembling that 

 of dimorphon. The constant susceptibility of guinea-pigs is, 

 however, in marked contrast with that of other laboratory 



