878 THE ANIMAL CARRIERS OF DISEASES 



Flagellate Diarrhcea and Dysentery. 



Parasites. 



Definitive 

 Host. 



Reser- 

 voir. 



Trans- 

 mission. 



Inter- 

 mediary 

 Host. 



Infection. 



Inter- 

 mediate 

 Host. 



Giavdia 

 intestinalis 

 and others. 



Man in 

 chronic cases 



and as 

 carriers, and 

 rats. 



Rats. 



Cysts 

 ingested. 



Flies. 



Cysts in- 

 gested with 

 contaminated 

 food or 

 drink. 



Man in 

 acute 

 cases. 



Sleeping Sickness. — We have already indicated that we think 

 that there are several forms of this disease — viz., that caused by — 



1. Trypanosoma gamhiense. — Synonym: T. nigeriense. 



2. Trypanosoma castellanii. — Synonyms: T. ugandense, T. gam- 

 hiense pro parte. 



3. Trypanosoma rhodesiense. 



4. Other Forms 0/ Trypanosomes. — (a) Some type of T. hrucet 

 in the laboratory infection of Professor Lanfranchi; {b) some type 

 of T. vivax found by Macfie, 



/ 



i, i - 



Fig. 461. — Glossina palpalis Robineau- Desvoidy, 1830: The Carrier 



OF THE TrYPANOSOME OF THE CaSTELLANI TyPE OF SLEEPING SiCKNESS. 



(From a photograph by J. J. BelL) 



The carrier of the first (T. gamhiense) has never been properly 

 studied. Possibly it is not Glossina palpalis, and as nothing can 

 be said definitely, we will not pursue this subject further, except 

 to say that Yorke and Blacklock consider man to be the principal 

 reservoir, with domestic cattle as a secondary reservoir. 



With regard to T. castellanii, we have noted that Miss Robertson's 

 researches have shown that it never multiplied in the vertebrate 

 in cells of the liver, spleen, or lungs, and that there was no schizo- 



