228 THE PROTOZOA 



Some authors consider types representing male, female and indifferent forms to be 

 noted during the developmental cycle. 



Other authorities think it possible that trypanosomes may encyst in the digestive 

 tract, and so the flies transmit the disease along with their faeces. This does not 

 seem to be possible in connection with human infections. Koch found several cases 

 where infection had taken place by coitus. This is the method of infection in T. 

 equiperdum, a trypanosome disease of horses. 



The various trypanocidal remedies, atoxyl, arsacetine, etc. , have not proven very 

 satisfactory. One of Ehrlich's latest products, arsenophenyl-glycine, however, has 

 given encouraging results; horses affected with surra having been cured by its use. 

 In man it has been given in doses of i gram without ill effects. 



T. rhodesiense. -This is a trypanosome reported for man by 

 Stephens and Fantham. The nucleus, instead of being in the center 

 as in T. gambiense, is quite near the blepharoplast. It is much more 

 virulent for laboratory animals than T. gambiense. It is transmitted 

 by G. morsitans and the developmental cycle is similar to that of T. 

 gambiense except that it seems that the important developmental cycle 

 occurs in the gut of the fly. 



Schizotrypanum cruzi (Trypanosoma cruzi) Chagas, 1909. A 

 human trypanosomiasis found in the state of Minas Geraes, in Brazil, is 

 caused by this protozoon. Cruz states that the specific protozoon is 

 transmitted by a bug of the genus Conorhinus (Reduviidae). 



This trypanosome is remarkable for the large size of its blepharoplast. In length 

 it is only a little longer than the diameter of a red cell. It is cultivable on blood 

 agar and can be transmitted to various laboratory animals, as guinea-pig, white 

 mice, and monkeys. 



Cruz thinks that a non-sexual cycle occurs in general tissues of man but that a 

 special sexual cycle occurs in the lung capillaries. In the lungs the parasite loses its 

 flagellum and becomes oval in shape. Subsequently eight daughter spores develop. 

 These spores or merozoites are liberated into the general circulation and each one 

 penetrates a red cell and develops into an adult trypanosome. When ingested by 

 Conorhinus they lose the flagellum and assume an oval Leishmania form, which 

 multiply by fission. Eventually there are produced trypanosome types which get 

 into the salivary glands and thence into man. Chiefly a disease of children with 

 swelling of neck, axillary and groin glands, anaemia, enlarged spleen, oedema of 

 eyelids and irregular fever. Usually fatal in children but less so in adult. In adults 

 apt to have goiter. 



Of the more important trypanosome diseases of animals may be mentioned: 



1. Nagana. Pathogenic for domesticated animals in South Africa. T. brucei. 



2. Surra. Pathogenic for horses in India and Philippines. T. evansi. 



3. Dourine. Transmitted by coitus in horses. T. equiperdum. 



4. Mai de caderas. Affects horses in South America. T. equinum. 



A harmless infection, especially in sewer rats, is due to T. lewisi. Transmission of 



