AFRICAN TRYPANOSOMIASIS 131 



The disease runs a fairly rapid course in man, killing him in three 

 to four months. Horses, donkeys and mules die in about thirty-eight 

 days. 



In the ox it is more chronic and some recover. 



It is fatal to horses as in man. No case infected has been known 

 to recoA^er, and remain free from the disease for a year. 



Goats, sheep, monkeys, dogs, rabbits, guinea-pigs and rats nearly 

 all die. Amongst these animals, three recovered out of 318 infected. 



It is highly probable that the Trypanosome of man in Nyasaland 

 and of nagana are not separate species. 



Carriers. 



Glossina morsitans and pallidipes are the carriers of nagana. 



About one per 500 of tsetses are infected with the trypanosome. 



The infected tsetses are equally numerous all the year round. 



If man is bitten bv one tsetse in the nagana area it is 500 to i 

 against his taking the disease. 



For its development in the tsetse see the development of T. gam- 

 biense, which is identical with T. brucei in this respect. 



Reservoir. 



The big game of the fly country are very heavily infected, more 

 than ;^2 per cent. These form the reservoir. 



The other trypanosome species pathogenic to domestic animals 

 were found as follows : T. pecorum, i4"4 per cent.; T. simiae, I'y per 

 cent.; T. capra), iri per cent, of all the game examined. Conse- 

 quently all such game should be exterminated (Bruce) in those areas. 



T. gambiense. 



History. 



It was first seen in the blood of man in 1901. 



It was found by Dr. Ford and described by Dr. Dutton, but it was 

 not then associated with Trypanosomiasis. 



The next year Dutton and Todd were sent out to investigate the 

 trypanosome at Bathurst. They reported that in their opinion the 

 blacks were immune to the disease, but that they acted as reservoirs 

 for the more susceptible whites. 



The real danger was ascertained by the Royal Society Commission 

 in Uganda, 1903. 



Distribution . 



North. — From St. Louis, at the mouth of the River Senegal, to the 

 Bahr-el-Ghazal district in the Egyptian Soudan. 



East. — Down to the eastern shore of Victoria Nyanza. 



South.- — To the southern end of Lake Tanganyika, the River 

 Luapula in Northern Rhodesia, and Donguela in Portuguese West 

 Africa. 



