PROTOMONADINA 275 



days and undergo multiplication which produces flagellates of 

 diverse size and form until 7th to 10th days when the organisms 

 show a very wide range of forms. From 10th to 12th days on, long 

 slender forms appear in great numbers and these migrate gradually 

 towards proventriculus in which they become predominant forms. 

 They further migrate to the salivary glands and attach themselves 

 to the duct-wall in crithidia form. Here the development continues 

 for 2-5 days and the flagellates finally transform themselves into 

 small trypanosomes which are now infective. These metacyclic tryp- 

 anosomes pass down through the ducts and hypopharynx. When the 

 fly bites a person, the trypanosomes enter the victim. In addition to 

 this so-called cyclic transmission, mechanical transmission may take 

 place. 





Fig. 121. Trypanosoma gambiense in a stained blood film of an inoculated 

 rat. Two individuals are in the process of division, X1150 (Kudo). 



Trypanosoma gambiense is a pathogenic protozoan which causes 

 Gambian or Central African sleeping sickness. The disease occurs in, 

 and confined to, central Africa within a zone on both sides of the 

 equator where the vectors, Glossma palpalis and G. tachinoides (on 

 the west coastal region) live. Many wild animals have been found 

 naturally infected by the organisms and are considered to be reser- 

 voir hosts. 



The chief lesions of infection are in the lymphatic glands and in 

 the central nervous system. In all cases, there is an extensive small- 

 cell infiltration of the perivascular lymphatic tissue throughout the 

 central nervous system. 



T. rhodesiense Stephens and Fantham (Fig. 122). Morphologically 

 similar to T. gambiense, but when inoculated into rats, the position 

 of the nucleus shifts in certain proportion (usually less than 5%) of 

 individuals toward the posterior end, near or behind the blepharo- 

 plast, together with the shortening of body. Some consider this 



