594 A MANUAL OF BACTERIOLOGY 



reaction. The Tr. Gambiense is pathogenic to monkeys, 

 and to a less extent to white rats and guinea-pigs. Cattle 

 and certain antelopes and other wild game may act as 

 reservoirs of the parasite, and it has been seriously sug- 

 gested to kill off all the big game in the affected areas. It 

 is conveyed by a tsetse-fly (Glossina palpalis), possibly by 

 other tsetses. 



The tsetse (and possibly other biting flies) may rarely convey 

 the disease by direct inoculation. Generally a cycle of develop- 

 ment is passed in the tsetse. The stages of this are not known 

 with certainty, but Koubaud has observed multiplication of the 

 parasites in the fly and the development of Herpetomonas forms. 

 According to the observations of Miss Kobertson, the flies 

 become infective so soon as the parasites reach the salivary 

 glands, from sixteen days onwards after feeding, and remain 

 infective for at least 70-80 days, and probably for the rest of their 

 lives. 



In Khodesia, a human trypanosome (Tr. Rhodesiense) occurs 

 which is distinct from, and more deadly than, Tr. Gambiense. The 

 G. palpalis does not occur in the district, and it is conveyed by 

 G. morsitans. The macronucleus of the parasite is frequently 

 situated between the blepharoplast and the posterior end. 



In Brazil another human trypanosome-like parasite has been 

 discovered by Chagas (Tr. or Schizotrypanum cruzi), which is 

 conveyed by a bug (Lamus megistus). 



Tr. Brucei is the causative parasite of nagana or tsetse- 

 fly disease of horses in Africa. 



Nagana is met with in large tracts of country in Zulu- 

 land and West Africa. It especially attacks the equines 

 horse, mule, and ass in which it is very fatal. The 

 animals become anaemic and emaciated ; there is a dis- 

 charge from the eyes and nose, staring coat, swelling of 

 the legs and neck, and fever. The animal dies two to six 

 weeks after infection. Oxen are also attacked, but a small 

 proportion recover. The dog, cat, rabbit, guinea-pig, 

 mouse and rat may be infected by inoculation with the 



