2l8 ANIMAL PARASITES 



The disease is transmitted from man to man by the tsetse-fly 

 (Glossina palpalis). In the fly it exists as a true parasite in a host, 

 and not merely passively. It becomes infective within three days 

 of biting and remains so for four weeks. 



The disease does not depend upon the age, sex of the individual, 

 nor upon drinking water, food, seasons, etc. 



The organism may be stained by the ordinary blood stains, mix- 

 tures such as Leishman's, Romanowsky's, etc., the nucleus, 

 centrosome and flagella, staining deepest. Thus far the T. gam- 

 biense has not been cultivated in artificial media. 



FIG. 79. Trypanosomes; showing ordinary structural appearance on left; in 

 middle a trypanosome undergoing division; on the right an agglutinated group. 

 (Tyson's Practice.) 



Novy has succeeded in growing the T. lewisii and T. brucei on 

 agar mixed with defibrinated rabbit's blood. These are the first 

 animal parasites to be cultivated artificially. 



Trypanosomiasis of South America is not unlike sleeping sickness 

 of Africa. It is caused by Tr. cruzi, a parasite of 8 spores, develop- 

 ing in organs, serum or red cells. It is transmitted by Conorrhinus 

 megistus, a large insect. 



In Dum Dum fever or Kala Azar, a disease occurring in India, 

 curious bodies, called Leishman-Donovan bodies have been found. 

 These resemble the malarial plasmodia roughly, and if cultivated 

 on blood agar elongated herpetomas-like bodies without undulating 

 membranes will develop. These bodies are evidently in the 



